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1. TO THIS IS AN OUTSTANDING ACHIEVEMENT AND I M PLEASED TO HEAR THAT A __ f In this issue of TRS8BIT MODEL 1 RS230 ASSEMg IBLER Nore OTE lt PART j TES POWE Y R MODEL 3 _ REPAIRS 3 INTO 2 THERE SEEMS TO BE ENOUGH INTEREST SHOWN TO JUSTIFY ALL THEIR HARD WORK AND EFFORTSU I BELIEVE THAT THIS HAS TO BE GOOD NEWS FOR EVERYONE INVOLVED WITH TRS 825 MATTHEW REED HAS RELEASED VARIOUS UPGRADES TO MOST OF HIS SOFTWAREL V1U 8 FOR THE EMULATOR V1U11 FOR TRSTOOLS AND VULUSU FOR TRS READ WRITEL FULL DETAILS ARE AVAILABLE FROM HIS WEBSITE THE MODEL 1 HAS JUST HAD IT S 36TH BIRTHDAYL I HOPE THEY HAD LOTS OF CAKE AT THE PARTY I VE COME ACROSS A FIRM BASED IN THE UK WHO HAVE OFFERED TO HELP WITH TANDY REPAIRS CANDU ICTUCOM ARE BASED IN LINCOLNU I VE PLACED CONTACT DETAILS ON THE HARDWARE SUPPORT PAGE OF OUR WEBSITE FOR THE NEXT EDITION MAV HAS GENEROUSLY OFFERED TO RUN A COLUMN ENTITLED ASK WHERE HE LL ENDEAVOUR TO ANSWER YOUR HISTORY AND HARDWARE COMPATIBILITY QUESTIONSU PLEASE CONTACT HIM DIRECTLY VIA HIS WEBSITE ON THE TRS 80 FORUM THERE HAS BEEN VARIOUS POSTINGS REGARDING A LUSK UPGRADE WITHIN THE KEYBOARD USING 161 CHIPSU I VE COME ACR
2. This is a picture of the bottom of the original prototype The connector that is plugged into the Pi is at the left The floppy disk connector is at the right be datae 3 9 3 Af 1O OO O O 0 20 ooo VOLUME 07 ISSUE DECEMBER 2013 PAGE 38 MISSILE DODGE I m sorry but I can t trace the author s of this super little program The website from where it was found has now vanished I think you ll agree it s a really clever bit of coding and as you all know I just love my one liners I set myself a challenge of writing a program using a single line of BASIC code After writing a few simple programs I wondered if it was possible to write a game in one line of code It turns out it was possible I wrote Missile Dodge where a player at the top of the screen has to move left or right to dodge missiles being fired at him from the bottom of the screen Although my original code was long since passed into the ether I was reminded of the challenge recently I decided to dig out a TRS 80 emulator and try to re create Missile Dodge ALIST B IFI THENCLS PRINT MISSLE DODGE Z LEFT X RIGHT PRINT DIFFIC ULTY INPUTD CLS I21 GOTOELSEFORX 1TOD PRINTE SS9 RNDK 642 1 N EXT PRINT PZP CPEEK C 14344 4 gt O 14344 271 ANDP lt 63 gt IFPEE KC 15368 P 3THENPRINT SCORE SELSEPRINT P 5 5 1 GOTO READY Min
3. une jum SKINS vo protuce a ufimuoe piece Gr ses a eee the last byte of performance out of the machine and the pilot the last drop of authenticity out of the simulation Other simulation programs produce at best a similarity towards flying With Jumbo you really feel that you are behind the controls The authors have used a number of gimmicks and programming techniques For instance it is possible to switch on an automatic pilot and to jump forward in time in increments of one minute or one hour otherwise of course a flight from London to New York or vice versa would take some 8 hours to simulate Whilst in this time skip the various controls are left as they are but fuel consumption and distance to go are taken forward at their correct rate A chart is supplied containing various items of data which you will need including the take off data for a 747 with various take off weights flap retractions climb and cruise speeds and descent distances Realising that not everybody can fly a 747 and that there is even a large proportion of the population that cannot fly anything two important items of assistance have been added First of all is the documentation This is split into two parts The second is a manual on flying the 747 In other words the instructions for running the program The first part however is what amounts to an instruction manual for flying It assumes that the user knows nothing about aircraft and although we do not pur
4. TRSSBIT VOLUME 07 ISSUE 03 SEPTEMBER 2013 PAGE 8 We should have expected register responds to most sorts of activity memory and registers th F regist and there must it going on with checking on cursor position character incrementing the cursor etc Likewis r to alter as that except loading have been a fair bit of displaying the the Refresh register and Program Counter have simply behaved in the normal way they would be expected to DE register pair Well it s a long story but here goes were designing the TRS 80 and were writing faced with the problem of implementing a video display t you know that You are routine using just upper case characters bul sooner or later the computer will be fitted with a aracter generator about which you have no information that will handle a chip the Rom is finalised ch impossible to write a display routine about which you know nothing and once ere s no way of th Th point to So that address in the computer address in Ram tine is really rou e solution is fixed upper case on but what is 401D doing in the Just altering it your Sa such 33H y 401DH to find out wher th imagine that you the Level 2 ROM LOWer case It is to have dedicated address in Rom which will ly Rom video driver program when we want to display a character
5. Mavric By 1982 the microcomputer world was in a state of change not just for Tandy but for all computer manufacturers Prior to 1981 there was just two main markets for micros namely that of powerful home and small business computers and small cheap home computers In the former category you have computers like the Apple II Commodore Pet 4032 and TRS 80 Model III and the latter category was contested by computers like the Commodore VIC 20 TRS 80 Color Computer and Sinclairs Just about this time IBM decided to join the market with its IBM PC aimed squarely at the market enjoyed by the Apple II Pet and TRS 80 Model I II III and its computer was a run away success It was anything but cheap and so had little effect on sales of cheap home computers though it did have an effect on most other business orientated micros Suddenly CP M monochrome screens 64K ram and single sided disk drives looked very old fashioned IBM was onto a winner and software companies flocked to the machine Compatible machines were produced and very quickly a new standard for microcomputing emerged which is still with us today the PC Most manufacturers realised to survive they needed to make PC compatible machines and out of that came companies like Compaq and Dell But going back to 82 even Tandy realised that it s new powerhouse products for 1983 the Model 4 12 and 16 were going to be eclipsed by the IBM PC and may have a limited lifesp
6. pressed If it s a CR jump to end of the routine If it sa backspace deal with it If it s a character we are prepared to accept if not ignore it is there room in the buffer for one more and if so put it there Display it and go back for another one TRSBBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 9 1 ORG 7800H 2 LOAD 7800H 3 CR EQU 13 4 BS EQU 8 6 7800 213D78 LD HL MESS1 7 7803 CD6578 CALL VIDEOUT 8 7806 214C78 LD HL BUFFER 9 7809 OE19 LD C 25 Length of BUFFER 11 780B 0600 TEXTIN LD B 0 Character count 12 780D CD7B78 KEYIN CALL KEYSCAN 13 7810 B7 OR A 14 7811 28FA JR Z KEYIN 15 7813 FEOD CP CR 16 7815 2825 JR Z TEXTEND 17 7817 FEO8 CP BS 18 7819 2000 JR NZ CHECK 19 781B 05 DEC B If lst key makes B negative 20 781C FAOB78 JP M TEXTIN so back to beginning 21 22 781F CD7178 CALL OUTPUT Display backspace 23 7822 2B DEC HL Go back one 24 7823 30620 LD HL clear character Buffer 25 7825 18E6 JR KEYIN 26 27 7827 FE20 CHECK CP 32 If less then 32 dec 28 7829 38E2 JR C KEYIN we don t want it 29 30 We now need A reg to check if Buffer full 31 So save the character on the stack first 32 782B P5 PUSH AF 33 782C 78 LD A B 34 782D B9 CP C 35 782E 3803 JR C NOTFUL Carry if B is less than C 36 7830 F1 POP AF Restore the stack 37 7831 18 DA JR KEYIN Wait for CR or BS 38 39 7833 F1 NOTFUL POP AF Restore character 40 7834 77
7. 196 142 001 008 149 02 POO 991214 LIA AAA 118 190 201 200 008 wal 60 09 98 92 80 22 8 2 04 42 90 3 81 16 253 tele progres cie M seconds Wacana aber of or core Babyroot versions Machine top and BASIC bottom New City New York 10956 Apote bevve poge 2 TRS BIT DR HOWE S SOFTWARE For the TRS 80 ih 1 amp 0 ademas of Tandy com VOLUME Q7 ISSUE DECEMBER 2913 DYNAMIC RAMS FOR tY EXPANSION PTT eY for your TRS 80 We have benchmarked processing of customer statements and aging reports and found that these reports run nearly twice as fast with THE SPOOLER installed THE SPOOLER pour wer anon program Price 100 Add 5 4 for condit card order Ade 15 tor COD orders wparwiet for 11d Model I version now available Phone 513 991 4496 or write Snapp Inc SOD Carnparnts Park Drivs Ginn 46565 4 ot __ 80 Microcomputing May 1980 TT PAGE 51 Modified Babyroot for Model 3 to continuously move from Low to High testing the remaining memory You will need to set this Diagnostic for the RM size that is in your Model 3 4 Original babyroot was in the May 1980 80Microc
8. Ar T Ab cul 4 ag LE xcu bi ab 21 4 Nro Sato ree SR Es puters That means all the Tandy 2000 software runs faster so you get the job done quicker Vast Storage Capacity Tandy 2000 s two floppy disk drives let you store more documents and crunch through bigger tasks with ease For even greater storage the Tandy 2000 HD features a built in 10 million character hard disk drive Flexible Ergonomic Design Tandy 2000 easily adapts to you Compare the Tandy TRS 80 Model 2000 and your environment In fact you can actually fine tune the the IBM Computer modular system to your personal needs Using our space saving options you have the smallest possible desk foot print only 21 6x31 1cm And the low profile 90 key keyboard with 12 function keys and a 10 key numeric datapad assures fast comfortable typing Easy Expansion Capabilities Add additional memory stun ning high resolution monochrome and color graphics our Digi Mouse and more And you can install most of these options yourself Compare the Tandy 2000 to Other MS DOS Computers in actual benchmark comparisons Tandy 2000 s true 16 bit microprocessor performed almost three times faster than the IBM PC Each Tandy 2000 disk drive offers over four times the storage of an IBM PC drive and twice that of the TI Profes sional Our color graphics are twice the resolution of COMPAQ or IBM an
9. OPPORTUNITY TO CHANGE THE MATRIX LAYOUT TO 5X7 CLE TDATR xxu xU ENN RUT RES ddd 3333333132120 1331231444133312212311221441133223314414411441 231 t F RIZ1TO4 REA MERTEF RLZHTOTSTEPRS INPUTS F RISITU PRIMTASCVAL eet Te LE NEST MEXT 3 ONCE AGAIN IT WAS PRODUCING A NUMBER CLEARLY i AND REASONABLY QUICKLY BUT THERE STILL REMAINED ONE MAIN PROBLEM I WOULD ALWAYS NEED TO PRINT x THAN ONE NUMBER AT A TIME UP TO SEVEN WOULD BE IDEAL THOUGH THERE IS ROOM FOR EIGHT A REASONABLY SIMPLE TASK IN THE USUAL RUN OF ke THINGS BUT I STILL WANTED TO KEEP THE PROGRAM 5 ONE LINER 50 I CHANGED THE INPUT STATEMENT TO A STRING AND CALCULATED THE LENGTH OF THE INPUT NUMBER STRING THEN I ADDED EEEE AN ADDITIONAL LOOP FOR NEXT T TO PRINT EACH NUMBER S 7TH PART FORMATION ACROSS THE SCREEN ONCE AGAIN I EXTRACTED THE INFORMATION USING TRSSBIT VOLUME 07 ISSUE 01 MARCH 2013 PAGE 4 VAL AND MIDS FUNCTIONS I ALSO NEEDED TO ADD A COUPLE OF SPACES TO THE PRINT STATEMENT TO FILL OUT THE NUMBERS I ALSO HAD TO FILL OUT THE SINGLE TO THE 5 CHARACTER MATRIX SIZE BECAUSE OF THESE CHANGES HAD TO SACRIFICE THE CONTINUOUS LOOP HOWEVER SINCE IT S ONLY A MATTER OF TYPING RUN EACH TIME I WANTED TO PRODUCE A LABEL I WASN T TOO WORRIED I ALSO DECIDED TO CHANGE THE TO A FOR NO OTHER REASON THAN I PREFERRED IT AS YOU VE SEEN THESE LITTLE PROGRAMS
10. If Line 5 all again loop Line 6 call the display routine Line 7 Just there Lines 15 to 20 calling 33H otherwise the A register is zero therwise carry on is typical of a keyboard input it will be NZ This The video display routine then restoring IY amp DE before returning Examining the registers befor sh in th itial values are e keystroke character and The problem with this routine the F co is tha then jump back do it call test and jump back routine The A register now has the character for the video so to give a breakpoint address Saving DE amp IY and and after we test this program ould show that the only ones that do not return their the A and F ones where the A will contain uld be anything it is limited to just CT CT d more of eaningful one keystroke an something more m ten such as a name or a quantity that no to keep first thing we need to do is until the lt Enter gt key is pressed like this 1 ORG 7800H 2 LOAD 7800H 3 7800 CDOE78 GETCHAR CALL KEYSCAN 4 7803 B7 OR A TRS amp BIT VOLUME 27 ISSUE 93 SEPTEMBER 2813 we will want to input The on accepting characters Insert the extra lines to the program so the beginning looks PAGE 13 5 7804 28FA JR Z GETCHAR 6 7806 CD1878 CALL OUTPUT 7 7809 F
11. THE ONLY DISAPPOINTMENT WAS THE FACT THAT I COULDN T SEE A TANDY ANYWHERE NEITHER WAS THERE ANY MENTION OF TRSSBIT TOO I DON T THINK THEY ARE AWARE OF ANYONE USING EARLY MICRO COMPUTERS OTHER THAN DISPLAYING THEM AS OLD TECHNOLOGY PERHAPS IF YOU EMAILED THEM THE LATEST COPY OF TRS amp BIT gt s IT WOULD PUT OUR NAME ON THE MAP SO TO SPEAK ONE THING WHICH DID CATCH MY EYE WAS AN ICL 28960 SERIES COMPUTER WITH EDSK6 DISK DRIVES 60 AND AS BIG AS A DOUBLE FRIDGE FREEZER REQUIRING MUCH MORE ELECTRICAL POWER THOUGH THEY TOLD ME THEY HOPE TO GET IT RUNNING IN THE NOT TOO DISTANT FUTURE I VE ENCLOSED A PHOTO OF THEIR ICL 2992 SETUP JUST TO REMIND YOU OF THOSE HAPPY TIMES WE HAD RUNNING RJE AND GEORGE 3 BEST WISHES 7 THANKS FOR THE EMAIL EeTe THE PHOTO TAKES ME BACK A WHILE I VE MANY HAPPY MEMORIES OF THAT TIME I CAN STILL REMEMBER THE WONDERFUL MEALS IN THE STAFF CANTEEN AND YOU HAVING TO LOAD ALL THOSE GEORGE CHAPTERS WITH THEIR CHECK DIGITS EVERY TIME AN UPGRADE WAS REQUIRED I VE PUT A LINK TO THE TNMOC ON THE WEBSITE THE NATIONAL MUSEUM OF COMPUTING TRSBBIT VOLUME 7 ISSUE 2 JUNE 2013 WWWe TNMOCeORG PAGE 3 THE NEW POWER SUPPLY FROM THE RIGHT STUFF LOST ONE OR BOTH OF YOUR MODEL I POWER SUPPLIES ARE YOURS WORN OUT OR JUST PLAIN BUSTED DID YOU JUST BUY OR INHERIT A MODEL I AND IT DIDN T C
12. Direction Select Cable pin 18 Selects the direction of movement of the R W head when the step signal is pulsed Step Cable pin 20 This short about 8 microseconds pulse indicated that the R W head should be moved one step in the direction indicated by the Direction Select pin Fortunately TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 35 the Raspberry Pi has programmable edge detect triggers that will watch for this and set a bit when the line is pulsed Since an actual floppy disk takes a couple of milliseconds or more to move the physical head from one track to the next but the emulator can move the virtual R W head almost instantly the timing is not critical I have been able to poll the edge detect signal rather than trying to use interrupts which are not well documented Write Data Cable pin 22 Not yet implemented This would contain the data to be written to the disk surface Write Gate Cable pin 24 Not yet implemented Signals that the write data is valid and should be written to the disk Stays low for the duration of the write operation Interface Circuitry There were two main considerations when choosing what ICs to interface between the Rasperry Pi and the TRS 90 expansion interface The first was the TTL logic 5v used by the TRS 80 which is not compatible with the lower voltage 3 3v logic on the Raspberry Pi The second was the very low resistance 150 ohm of the pull up resistors This
13. It turns out all the old programming tricks came flooding back to me and I m pretty confident that this code is faithful to my original program I wrote the program on this emulator http ht homeserver hu bin emu ht1080z v1 6 2 zip But I also tested them on TRS32 http www trs 80emulators com so it should work on almost anything Although I have been told that some emulators run too fast for the game to be playable the two emulators I mention seem to simulate the clock speed of the original TRS 80 so the game plays fine TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 39 A few notes 1 the maximum line length for a BASIC program on these is 254 characters but the standard input buffer for entering commands isn t that big so you have to input part of the line then edit the line to complete it To edit a line do EDIT 0 Then x will take you to the end to append more 2 in this basic the parser doesn t require spaces to correctly identify commands so there is a saving there Doesn t make it very readable though 3 the screen is 64 characters across by 16 rows down The PRINT command allows you to place output anywhere on the screen with position 0 at the top left and 1023 at the bottom right 4 PEEK X allows you to read memory address X Address 14344 is part of the keyboard memory map and allows me to see if a key is pressed or not I don t use the built in INKEYS function in BASIC because t
14. 10 Make everything Integers 20 Give Y the value 0807Hex and store it in RAM 30 Find out where Y is stored 40 Have a peek at what s there 50 Try your own numbers Alternatively you could try POKEing some values into V and 1 and then finding out what Y had become What you should observe is that any value of Y is held in RAM such that the remainder from dividing by 256 is stored at the byte in memory pointed to by VARPTR Y and the number of 256 s in Y is stored at the next byte i e VARPTR Y 1 This is VERY IMPORTANT and we shall use this fact in PART 2 with USR routines Affordable Expandable Available video genie system Features Guide Prices 16K RAM expandable to 48K Video Genie EG3003 12K Microsoft BASIC in ROM Expander box incl RS232 225 TRS 80 Level 11 software compatible Expander Box 195 00 Plugs directly into a 625 line TV EG100 12 monitor 69 00 Connects to second cassette recorder 16K 100 RAM card 100 00 5 32K 100 card 140 00 Video output for monitor x gt J Completely self contained Easily portable 9 B W high quality monitor 85 00 Expandable to include 4 disk drives 9 Green phosphor monitor 95 00 100 bus available Single disk drive 225 00 Now with VU meter Psi Sk crise 440 00 echnical Manual 5 00 Including 4 cursor control keys going Quid ST Wide range of accessories available All prices exclude VAT if app
15. 14 7833 7E VIDEOUT LD A HL 15 7834 23 INC HL 16 7835 B7 OR A TRS amp BIT VOLUME 27 ISSUE 93 SEPTEMBER 2813 PAGE 18 17 7836 C8 RET Z 18 7837 CD3F78 CALL OUTPUT 19 783A FEOD CP CR 20 783C 20F5 NZ VIDEOUT 21 783E C9 RET 22 783F D5 OUTPUT PUSH DE 23 7840 FDE5 PUSH IY 24 7842 CD3300 CALL 33H 25 7845 FDF1 POP IY 26 7847 D1 POP DE 27 7848 C9 RET 28 END Testing this version in the usual way will give the following on the VDU Note that Mess3 follows immediately after Mess2 Z gt J7800H Brkpt gt 7812H PRESS ENTER TESTING gt gt gt gt lt lt gt gt gt gt gt gt gt Z gt There are of course other ways of achieving the same objective If you should examine a machine code program generated by a compiler or program generator then you will find that usually each message is preceded by a single byte value giving the number of characters for output This quantity is loaded into the B register and the output routine goes round a loop displaying and decrementing B until B becomes exhausted There s nice little 780 instruction Specifically for the B register called Decrement and Jump If Not Zero which does it all for us in one go Taking our original example and rewriting this way it becomes 1 ORG 78008 2 LOAD 78008 3 CR EQU 13 4 7800 210778 LD HL M
16. 39 42 44 48 CONTENTS WATERMARKING BASIC PROGRAMS AJ HARDING THIS ARTICLE FIRST APPEARED IN THE MOLIMERX CATALOGUE AND IS A SIMPLE WAY OF PROTECTING YOUR BASIC PROGRAMS IVAN KENNEY S MODEL 4 IAN MAVRIC MAV FIRST WROTE THIS ARTICLE FOR SYDTRUG NEWS JUST HOW DOES HE SORT OUT ALL THOSE PROBLEMS ASSEMBLER NOTES PART 4 LAURIE SHIELDS THE FINAL PART OF LAURIE S BRILLIANT INTRODUCTION TO ASSEMBLER PROGRAMMINGe LAURIE HAD KINDLY GIVEN PERMISSION FOR THE 4 PARTS TO BE MADE INTO A BOOKLET FOR DOWNLOADINGe IT WILL BE AVAILABLE FROM THE WEBSITE CTRS 80 ORGeUKs JUST IN CASE YOU D FORGOTTEN IN THE NEW YEAR IN MAV S WORKSHOP IAN MAVRIC THE NEXT INSTALMENT OF MAV S HARD DISK SERIES THIS WILL MAKE ALL US MODEL 1 FANS SMILE IT S CHRISTMAS DEE AND I WISH YOU ALL A VERY MERRY CHRISTMAS UPGRADING MODEL 1 USING 64K CHIPS LEW MCCOY amp FRED TREASURE AN EXTRACT FROM CQ MAGAZINE VIRTUAL FLOPPY DISK USING A RASPBERRY PI ALAN PAGE ALAN BLOGS DETAILS OF A MODEL 1 UPGRADE MISSILE DODGE AUTHOR S UNKNOWN A TRULY BRILLIANT ONE LINER WITH FULL EXPLANATION IT S JUST HAS TO BE AN XMAS DAY SPECIAL TREAT ASK MAV HARDWARE QUESTIONS ON THE MODEL 4 IAN MAVRIC MAV ITEMISES SOME OF THE M4 QUESTIONS HE S BEEN ASKEDe HOPEFULLY WE CAN MAKE THIS A REGULAR FEATURE FOR ALL TYPES OF HARDWARE GOODBYE HARD DISK HELLO FREHD GARRY HOWARTH GARRY FINDS A NEW LEASE OF LIFE FOR HIS OLD HARDWARE USING THE L
17. ouy spusl g 2 peidesce ONW VSIA pz pejdeooe siopio euoude a Teaoidde o jelqns peideooe 1 MO eq sseIppe 10 puss O jo d yore Ajenbtun pejeorpep sjrexu ORF uonezoueb 1s1g eui jsou hs ueo jt 1eulojsno JI eui Ist e2ud WOT 1oe es g noA 1ejuud jyoeds pue SANINA YALNdNOD 9j 10 v OL MOH MOo 9 ard nd umoiq pel en q qerq seprseq Sio oo piepuejs ino jo Aue ur uoqqu pe urun ue Durqut o1 u u pue Aq sjno juud 0 10102 ppe ued peey juud y uoqqu uo yoq 1 eu seonpei si umururu e je peeu ey esn ued nok seje1ouojep jno juud uoqqu eu Ag jueuoduioo pepueixg oueumueudje 10 o1ydei6 suodei ejai5er Ayjenb yy dsuo 19A910j 92npoid g sed 1ejuud jo ueds sso1oe Sj nsei juejsisuoO pue repus Sojeorput 1euliojsnz peeu 3uud y sey uoqqu 0g euo s1s 1 1no ujbue 2 uo Durpuedep 001 06 0 Suynuud uoqqu ouqej poop y
18. pa 5 gt avec i A y E 1 Neer aee VISAVTWW aM Sio mM 2 7 eorf past Fr E ll 43 mu 4 224 d v 1 Papia Pm L TT Tt White and Yellow wire on the WD1010 HDC TRS BIT VOLUME 7 ISSUE 2 JUNE 2913 PAGE 26 The BEST in TRS 80s Call The Right Stuff Ask for Ian The number is 61 416 184 893 That s The Right Stuff And he s in Melbourne http ianmav customer netspace net au trs80 TRS BIT VOLUME 27 ISSUE 022 JUNE 2913 PAGE 27 HERE S A SUPER LITTLE PROGRAM SENTIMENTAL VALUE FOR IRA RESCUED FOR ME MANY YEAR AGO TWICKENHAM I REMEMBER AT THE TIME BUILT THE CASSETTE PORT SERIAL T SERIAL PRINTER DRIVER ME FROM ME BY FREDDIE DESIGNED SEE TRSSBIT VOL 2 SYSTEM THERE WASN T M AS YOU CAN 1 LEVEL 1 NO DOUBT IMAGINE WHICH HAS A LOT OF IT WAS ONE OF THE PROGRAMS WHICH MY OLD FLOPPY DISKS IT WAS GIVEN NICHOLS OF OPTRONICS IN WHEN I WAS ATTENDING AN OPEN DAY WITH NATGUG IT WAS A GOD SEND AS I HAD JUST INTERFACE WHICH LEON HELLER ISSUE 2 AND HAVING ONLY A 4K MUCH SOFTWARE AVAILABLE THE PROGRAM WAS ALWAYS CASSETTE BASED AS I DIDN T HAVE A DISK SYSTEM A LATER DATE HE CASE T IF YOU WOULD LIKE A COPY OF JUST IN CASE BEING 320 YEARS HENCE THOUGH BUT I CLEARLY REMEMBER
19. R S T D V M 3808 X Y Z 3810 M amp 0 1 2 3 4 5 6 7 3820 lt gt 8 9 3840 Enter Clear Break UA DA LA RA Space Bar 3880 Shift 3C00H Video If Bit 7 1 is Set then Graphics 3FFFH Video Memory Note UA DA LA and RA are the arrow keys Viz up down left and right up TO SOMETHING SPECIAL OR NEW 1 HOW ABOUT LETTING b AL KNOW ABOUT IT 58 VOLUME 7 ISSUE 04 DECEMBER 2013 PAGE 23 IN MAV S WORKSHOP by Ian Mavric Part 4 of the HARD DRIVE Trilogy HARD DRIVES AND THE TRS 80 MODEL I Last time I concluded my trilogy of hard drive articles for the Model III and 4 I focussed on the Model III and 4 since 99 of hard drives sold to the 8 bit 2780 systems were used on those computers In fact not many people know that a hard drive could be even connected to a Model I Obviously I own one I use it a few times a week and I was part of the team who helped make the FreHD hard drive emulator work with the Model I so I think I know a bit about them HISTORY In 1977 when Tandy designed and built the first few machines with Level I BASIC and 250 baud cassette storage they could hardly have imagined that only 5 or 6 years later Winchester hard disk storage similar to that available on mini computers was going to be affordable and store megabytes of data When you are designing a 4K microcomputer 5 megabytes must have sounded like a miracle When Tandy went back to the dr
20. Whence value can be any decimal hexadecimal number in the range 0 OFFFFH It could also be a label with an associated numeric value known to the assembler This is the big difference in thinking between Basic and machine code Basic programs are completely position independent and toa large extent machine or even type of computer independent Machine code is written not just for a particular central processor but also very likely for a particular configuration of computer and further more to occupy and work in only one part of that computers memory This often raises the question Why bother but we won t go into that just yet The value used for the ORG of your program depends on the 58 VOLUME 27 ISSUE 2 JUNE 2013 PAGE 5 purpose of the program If you were re writing the whole of the Level 2 Rom you would start with an ORG 0 not caring whether it was Hexadecimal or ordinary numbers and then grow old gracefully Most of the time however we want to create a program to work in a section of unused memory and a convenient place is the upper part of the 16K Ram as this is not used by the Aculab cassette or any of the Disc operating systems All our programs therefore will be based on an ORG of 7800Hex but of course you could change it if you wanted to Our assembly language source code notice the crafty way these new words creep in now looks like this ORG 7800H END and as some folk might
21. altered as well so we must be prepared to look after both DE and IY if we want to use 33H Since we will probably use it over and over again during a program we may as well set up a general purpose subroutine labeled say OUTPUT that we can simply CALL for output It will look like this OUTPUT PUSH DE PUSH IY CALL 33H POP IY POP DE RETURN By pushing the contents of DE and IY onto the stack we can allow the ROM to do what it wills with them as after it has finished we simply pop them back off the stack being careful not to get them crossed over and thus we are in total control There are two other routines concerned with data input output that are used in a very similar fashion The first is located at 3BH and outputs to the lineprinter The difference between this and the one for the video is that 33H is bomb proof and if we call it then as sure as eggs is eggs the character in the A register will appear instantly on the video even if the whole screen needs to be scrolled if we call 3BH and a printer isn t connected then th computer will hang up for ever and a day waiting for one to be attached And what s more even if the printer is there TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 11 and working some of them don t get round to actually doing any printing until a carriage return is sent to signal
22. i How do we link our program to Basic ii How do we ensure our program will not upset Basic Lets tackle the second one first When Basic hands control over to a USR routine it always ensures that there is nothing important in the AF or HL registers so we can do what we like with those As for the BC and other registers we do not know whether what they contain is of any consequence or not so we had better save the contents of BC before we use it and restore whatever was there when we are finished Fortunately the 280 has a very useful technique of saving and restoring the contents of a register pair It is known as the stack and works a bit like a spring loaded money box allowing you to push values into storage and pop them back again afterwards The stack is also used by the 780 itself for remembering return addresses from subroutines Most machine code programmers at one stage or another get their pushes and pops crossed with their calls and returns generating something that resembles more of an infestation than a bug but more of that later Sufficient to say that with our program all we need to know and do is PUSH BC at the start and POP BC at the end But what happens at the end How do we get back to Basic Well the way Basic processes a USR statement is to call it like a subroutine A subroutine in machine code works just like one in Basic and needs at least one happy return abbreviated to RET Make the necessary cha
23. short together pins 2 and 3 Rx and Tx and run a comms program on the TRS 80 and see if what is typed appears on the screen It s called a loopback test If I get no response on the loopback test I connect the RS232 to another known good TRS 80 via a null modem cable both computers running comms programs and see if there is one way communication This should be your first step before starting to suspect problem parts If there is no communication there could be problems with the BRG UART or line drivers but if you get 1 way communication you ve already eliminated the BRG as the culprit UART OR LINE DRIVER This then points to a problem with the UART or line drivers The UART is easy to spot its that big socketed 40pin chip and in a Model I RS232 its a TR1602 which design and implementation dates back to the 1970s It works well at all common baud rates 300 600 1200 and 2400 but like a lot of early devices doesn t like to get too hot and is pretty unforgiving if shorted out Radio Shack in its infinite wisdom puts it an un vented compartment under a hot monitor so its life in the TRS 80 application is arduous Then the RS232 manual shows how to build custom cables for serial applications like connections to serial printers and modems which if you build wrong or short can easily blow the UART There is not much to testing the UART but if you know your BRG is good then 90 of the time the problem will lie with the UART They can be
24. sjueo g st qu Bumur jo 1500 suoqqu Jo 802 sejeururqe V SA39WLNWAGVW 353 1 SA3AIO W33INI OW 6 61 62 H XM 9X T 6 SN xexu JLI 25 02 06 2 8 1 21 xexug oe suorsueur e qejreAe SIOJOU A022 s uexu IEN Ssiejuud jeeym Astep osje eoueunojred jue o2xe uoneiedo ayes 10 suoneouto sds s n oegmueul IO jueouqng peris nuioe xew Op INO uounquistp ue jey re rdeo PIA UOqqu et perrejsuer SI xut eui punoie sessed uoqqu sy 10joui PS xut jo sdorp Z ueure e Surur punore uoqqiu 1exu y sjoodg 10 peor T isdeys see UJ HUOM SIOA MOH ur SATANI OVIA 000 0p 1240 gg ounf jo sy diop uosdg jo xieurepei st uosdgy e2ud 001 08 01 NOSd 110ddns osje ued jeu OVW TOOdS MOU m pueurop pue Ayiqisesy FLON joods ueAup 1ojoui dn exej Sy uo dn punom pexur e1 ueeq sey uoqqu eui 100w sy sepepuasip V d Areuoye s SI 19 Sue1 3ul 5 eu
25. so first of all CALL OUTPUT to do it on the video and then we must move the value in HL back one and zap the character in the buffer before going round again for the next character That has disposed of the keys less than 32 that we are interested in so now to check on what is in the A register and simply ignore anything less by going back to KEYIN OK we have a valid character but have we got room in the buffer to store it To find out means doing sums with the A register but we can t do that without losing the important character in A so the best thing to do is PUSH it on to the stack Comparing B with C by putting one of them in A first will give the answer in the Carry flag to the state of the buffer We now have two things to do and if we get them in the wrong order we are in trouble The wrong way would be to POP AF to get the character back and then jump back to KEYIN on No Carry if the buffer was full Why wrong Well the important carry condition in the F register would be altered when the old values off the stack were popped so we must decide on whether or not there is room in the buffer before Popping AF TRS BIT VOLUME 07 ISSUE 04 DECEMBER 2013 PAGE 12 If there is room then we put the character into the buffer using the neat instruction load the contents of the memory address in HL with the A register Increment the value in HL to point to the next available space add one to B as our character count an
26. the Model III Rom image and to boot LS DOS directly off the FreHD Diving head first into the junk box I found the backups of my old hard drive and transferred them over to the FreHD Took a deep breath and pressed reset BINGO The computer booted directly off the FreHD without a boot floppy Smiles all round Boosted by this I next loaded a Model III system disk into drive 0 took another deep breath pressed reset and the 4P loaded the MODELA III file from the FreHD in about one second Not having a working hard drive I could not do any comparison tests but according to my notes it took the computer nearly 3 seconds to load the MODELA III file from the old hard drive so this is a big improvement Happy that all was working OK I sent a copy of the self booting FreHD image to Ian for testing Having used Adam Rubin s mods to LS DOS for over 20 years without having a single problem I was surprised when Ian could not get them to work on his computer A problem with the later GA versions of the was causing drive 0 to hang After a lot of work trying different drivers I managed to track down a later copy of Adam s patches that cured the problem TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 45 Fred Vercoven has now developed patches for the Model III and 4 4P ROM that will allow booting any operating system directly from the FreHD via a menu which makes all of the above hard work redundant oh well as Edward Kelly s
27. ur old first from earlier programs that the output routine will finish with a CR o To make our rout this program in that all to flag the value still in the A register so we check on loop back for the next it was a CR then VIDEOUT finishes with a return our strings therwise VIDEOUT doesn t tine more useful it would be a string in mid line so to ed non the end of a string small addition to make a IF 2 loading A with it is zero then the Z280 that the zero flag is THEN RETURN In 1 assembler it s as simple as RET Z Thus we ha ve two exits from VIDEOUT the first is to leave immediately if the next character it gets is zero and the second exit is following the output of a CR The program with a few added messages now becomes 1 ORG 7800H 2 LOAD 7800H 3 CR EQU 13 4 7800 211378 LD HL MESS1 5 7803 CD3378 CALL VIDEOUT 6 7806 211F78 LD HL MESS2 7 7809 CD3378 CALL VIDEOUT 8 780C 212878 LD HL MESS3 9 780F CD3378 CALL VIDEOUT 10 7812 00 NOP For Breakpoint 11 7813 50524553 MESS1 DB PRESS ENTER CR 7817 5320454E 781B 5445520D 12 781F 54455354 MESS2 TESTING 0 12 7823 494E473E 12 7827 13 782B 3C3C3C2E MESS3 DB lt lt gt gt gt CR 13 782F 3E3E3E0D
28. which tests all facets of the machine It is THE best program for testing the memory and located some bad memory chips in the upper 64K of this 128K machine TRS 80s don t extensively test their memory so a machine can appear OK but may crash on certain programs and run fine with others if they reside in different areas of the memory Only a proper test program can find them out With the computer together and booting regularly I was pretty pleased with the results but given the age of the machine I ran some diagnostics on the floppy disk controller which gave a pretty ordinary result This happens a lot with old systems as parts degrade over time Replacing the FDC on a Model 4 necessitates removing the motherboard which I did and replace the FDC and ran the tests again and got similarly ordinary results Fiddlesticks noticed the results change on the test program and scope readouts as I leaned on the 58 VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 6 white interconnect cable which joins the FDC to the motherboard Eureka I changed the flaky white cable and the problem went away In no time it was running MultiDos Ivan s favourite OS and the computer was finished off ready to return to its happy owner Mavric is an IT Specialist who also restores and collects TRS 80 s and classic cars He live with his wife and kids in Melbourne Austral lia 58 VOLUME 27
29. CN80 shows how to patch various drivers to use on the Model I TRSHD1 DCT can be patched to configure a Tandy 15Meg 26 4155 hard drive called TRSHD15 DCT Around the mid 1980s Radio Shack released a Model III hard disk driver called TRSHD5 DCT which can also be patched to become TRSHD51 DCT and for the first time allows you to dynamically configure a hard drive with both heads and cylinders But really messing around with old drivers is not a consistent approach and the best solution would be to use RSHARDx which we already use on the Model III and 4 MODERN DRIVERS Fortunately the work has already been done for us and in the same CN80 article the authors explain how to patch RSHARD5 DCT to become RSHARD1 DCT and it works well As well as being able to specify heads and cylinders you can also partition by head or cylinder maximising the use of your hard drive or FreHD 40Mb hard drive partitioning is easy and with some thought a hard drive can be partitioned up to 65Mb capacity over 7 partitions Not bad for an ancient computer originally released with 4K of memory and 250 baud cassette tape storage CONCLUSION Hard drives had been available for the TRS 80 Model I during a very brief period from 1982 84 and have since been rare and almost forgotten With the advent of FreHD technology the desire to add a hard drive to the Model I generated new interest among enthusiasts and now with my M1 Hard Drive adapter and updated drive
30. COPYING IT TO DISK AT I DON T THINK I ENVISAGED TO SAVE YOU TYPING IT INO PLEASE EMAIL I LL SORT OUT A VIRTUAL DISK OR CASSETTE CASSETTE PROGRAM ONCE 2400 4800 9600 B2 300 B3 B5 1200 Bo FILE FOR YOU IF YOU NEED A REAL AGAIN PLEASE EMAIL ME 10 CLS 15 PRINT MEMORY SIZES ARE 16 PRINT 20 PRINT 4K 20360 30 PRINT 16K 32650 40 PRINT 32K 49030 50 PRINT 48K 65420 60 PRINT 70 PRINT BAUD RATES ARE 110 450 80 PRINT 150 600 90 PRINT 300 1200 100 PRINT PENCIL BAUD RATES BX 110 PRINT 110 B1 150 120 PRINT 450 B4 600 1000 BASIC PROGRAM FOR INITIALIZING TRS232 PRINTER INTERFACE 1020 MADE UNDER LICENCE 1040 BY OPTRONICS TWICKENHAM 1060 SET MEMORY SIZE LEAVE AT LEAST 110 BYTES 80 POKE 16553 255 INPUT 10 00 HB INT MS 256 LB MS 256 HB 120 POKE 0 TO 105 READ D 16422 LB POKE 16423 HB 140 IF MS gt 32767 THEN MS MS 65536 160 180 POKE PROGRAM INTO MEMORY BAUD RATE B BR 1 1200 FOR I 1220 POKE MS I D NEXT 1240 1260 SET BAUD RATE 1280 INPUT 1290 IF B 110 THEN 1500 ENTER MEMORY SIZE MS MS MS 1 TRS 6BIT VOLUME 027 ISSUE 02 JUNE 2013 PAGE 28 1300 1320 IF 150 OR 300 OR 450 B 600 THEN 1380 IF B 1200 OR B 2400 OR B 4800 OR B 9600 THEN 1440 1340 1380 1420 1440 1480 1500 1540 1560 1580 1600 1620 1
31. I WAS AHEAD SO TO SPEAK AND STICK TO THE ONE LINERs AS ORIGINALLY PRODUCED L UST PRESS THE BREAK KEY WHEN YOU VE HAS ENOUGH 18 DATA 9449 15260 392 1536 Lr 256 1083 ced de eR 1 DEF INTA 2 FORZ RTQ READA UL Z se HEAT STEPS A INKE TS THEN HEATELSEPR INTAG AS DEFUBRBEVARPTROU 0204 INERT TRS BBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 25 IN MAV S WORKSHOP by Ian Mavric SETTING UP TRS 80 MODEL III AND 4 HARD DRIVE PARTITIONS Ok so you ve procured your hard drive from eBay CraigsList or one of the other myriad of places where they come up for sale from time to time You ve made new cables and following the steps outlined in the last issue have a hard drive which powers up and it s ready to partition for use on your TRS 80 Model III or 4 DOS AND HARD DISK DRIVER CHOICES Just about every operating system for the TRS 80 can be made to work with a hard drive this includes NEWDOS 80 DOSPLUS TRSDOS 6 CP M and even MultiDos But to my mind only two operating systems work properly with hard drives having the least number of compatibility issues and that is LDOS 5 3 1 for the Model III and LS DOS 6 3 1 for the Model 4 That is not to say the other operating systems mentioned don t do the job but I have used LDOS and LS DOS for 20 years with no issues and to me it is the de facto OS for hard disk users I should also point out that when Tandy first r
32. ISSUE 24 DECEMBER 2013 PAGE 7 ASSEMBLER NOTES Part 4 Laurie Shields Chapter 8 Getting it from the Keyboard Now that we are all at home putting it on the video the next step is to get it from the keyboard We got an inkling of the possible complications earlier and now it s for real Prising the cap of one of the keys only if you have an early TRS 80 is the nearest you will ever come to seeing a bit The keyboard is logically connected to a block of memory and each key arranged in sets of eight makes or breaks a little contact This sets or clears one bit of the eight that make up the byte at its memory address It all sounds very complicated and believe me decoding the keyboard is no game for amateurs Fortunately we don t have to as Tandy have provided 2BH for us to save all the trouble Now saving us all the trouble is perhaps not quite as you would express it if you knew what was coming as all that Tandy have given us is a very fundamental call that just instantaneously scans the keys and returns with the value of whatever key was being pressed If we weren t quick enough with our fingers then hard luck and what s more we have to save DE amp IY first That s the sum total of the official machine code keyboard input information Let s set ourselves the problem of accepting from the keyboard a string of characters that we need to save for use later in our program As the characters are keyed in we will arrange t
33. JUNE 29013 PAGE 15 Back to our program We left it with a lot of coding just to check if the BC register pair had reduced to zero Consider now what would be the result of doing an OR operation between the B and C registers If either of the registers had just one bit not equal to zero the final result would reflect this condition and it would not be zero So we now have a means of checking BC in one go or have we Well we nearly have remember one of the values for the OR command needs to be in the A register first so it looks like this 7 LD A B load the contents of the B register into A 8 OR C test if either of them is not zero 9 JP NZ LOOP 10 END You have now been introduced to the true assembler s abiding passion trying to save the odd byte here and there In general the main objective of Basic programmers is to get their creations working without any error messages Until the OM appears very few ever worry about how much memory is being used With true machine code it is very different Whilst the program is being assembled the hard facts are there on the Screen and every byte that is used is open to criticism There are of course the people who use macros relocatable object modules and linking loaders who neither know nor care about such niceties but we will have none of their ways of working here The designers of the Z80 haven t finished with us yet though Being true men of spirit they ha
34. Mie hs reme M y i PAGE 34 BELIEVE IT OR NOT BOB BOYD BOUGHT A HARD DRIVE OFF EBAY AND IT DIDN T WORK SO HE HAD SOMEONE THERE PERFORM THE ROY T BECK 3 WIRES MODIFICATION CWHICH IS EXPLAINED IN THIS ISSUE SEE PAGE 21 BUT THEY DID IT WRONG SO BOB SENT ME THE HARD DRIVE UNIT FROM PHILADELPHIA USA TO MELBOURNE AUSTRALIA BUT THE WD181 HDC BOARD HAD BEEN SHORTED OUT AND WAS NOT FIXABLE BOB THEN LOCATED ANOTHER HARD DRIVE ON EBAY BUT WHEN HE GOT IT HOME FOUND A COUPLE OF HORNET S NESTS INSIDE IT AND IT WAS THE EARLIER amp X308 HDC ANYWAY HE SENT IT TO TO SEE WHAT I COULD DO WITH IT AND AFTER SOME HOURS CLEANING THE BOARD AND DRYING IT IN THE HOT AUSTRALIAN SUN I CAUTIOUSLY PLUGGED IT IN AND IT WORKED IT NEEDED A FEW FINE ADJUSTMENTS BUT IT WORKED WELL AND WITHIN WEEK WAS ON ITS WAY BACK TO PHILADELPHIA WHERE ITS IN DAILY USE NOW BEFORE AFTER TRS BIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 35 TRS 80 GENIE SOFTWARE First there was Invaders then came Asteroids and now DEFEND Carrying on in the same tradition Defend is a fast arcade type action game complete with sound effects Enemy spaceships come at you fast and furiously If you succeed in shooting them down before they get your ships you must still get yourself through a meteor shower but at least they don t shoot at you and finally if you emerge unscathed you must navigate a tunnel in order to get yourself completely out
35. NUMBERIN CD9C78 KEYIN2 B7 28FA FEOD C8 08 2009 05 55 56 53 58 59 60 61 62 7865 7868 7869 786B 786D 786F 7871 FA5578 2B 3620 1814 FE30 38E6 FE3A CHECKNUM TRS BIT CONVERTEND VOLUME 97 ISSUE 04 DECEMBER 2913 DS 5 DW 0 PUSH IY PUSH HL POP IY LD HL 0 no input LD A B OR A JR Z CONVERTEND PUSH HL POP DE ADD HL ADD HL ADD HL DE ADD HL HL LD A IY 0 SUB 30H LD E A LD D 0 ADD HL DE INC DJNZ TIMESTEN POP RET HL HL LD B 0 CALL KEYSCAN OR A JR 2 CP CR RET Z CP BS JR NZ DEC B JP M NUMBERIN DEC HL LD HL JR NUMBVDU KEYIN2 CHECKNUM CP 0 JR C KEYIN2 CP 9 41 PAGE 17 63 7873 30E2 JR NC KEYIN2 64 7875 F5 PUSH AF 65 7876 78 LD A B 66 7877 B9 CP C 67 7878 3803 JR C NOTFUL 68 787A 1 POP AF 69 787B 18DA JR KEYIN2 70 71 787D Fl NOTFUL POP AF 72 787E 77 LD HL A 73 787 23 INC HL 74 7880 04 INC B 75 7881 CD9278 NUMBVDU CALL OUTPUT 76 7884 18D1 JR KEYIN2 78 7886 7E VIDEOUT LD A HL etc An alternative approach might be to use the original TEXTIN routine for any input and check it for numeric validity before conversion This would probably produce a more universal solution but would have added to the complexity For storing the final answer we have asked for two bytes of memory to be reserved with the pseudo op DW Define Word A Word in Z80 jargon is two bytes one
36. On the later small WD1010 HDC you need to solder the white wire to the leg of R38 closest to U28 and the yellow wire to the leg of R23 closest to U23 see Picture 4 WHAT TO EXPECT Once these modifications have been made the drive should still power up and go through its test sequence normally On the 8x300 the Active light stays off until the self checking is done then the light stays on unless the drive is stepping in which case the light flashes off momentarily On the WD1010 the Active light is on when powered up and when all self checking is complete the light goes out only flashing momentarily while the drive is stepping You can now set aside the Tandon MFM and replace it with any MFM hard drive you can find on eBay Craigslist etc My TRSSBIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 22 personal preference is for Seagate ST 225 20Meg and ST 251 1 42Meg hard drives as well as NEC D3142 D5136H Miniscribe 8438 and Microscience HH 1050 The Redhill web Site has many good MFM hard drive recommendations as well Before you start setting it up you need to know the specs for the replacement hard drive as they are not always indicated on the drive itself in fact drives which are labelled with how many heads and cylinders they have are quite rare Fortunately google is your friend and you can find the specs on just about any MFM hard drive in a few moments It is handy as well to check if you are installing
37. V seouei9jgtp OM ym uorneredo jo e diouud sures eui sesn joodg TeszeAtu sn H33INI OWN pepeeu US esoouo 10102 eu ut xut 1exu SANTINA NOO pexurun ue 195 10 sebpugi1eo 1o oo 1 1exu esn pue pe1o o2 jo emog 191104 LIX Jeyjoue 1o oS no oq 61500 jueurieoe dei ebpuiieo uoqqu A eouoead pue jr enb jno4uud um A ojerpeurur 10 JNO Jo 1500 eu uey sse 35 Sud 19je1 esee d OPP pejeorpep oed 917 pue od uexu sjoods 10 eDie y 100465 jeszearug sn Sel uoo je ON x wur JLM SINSDBIA snf reyjoue IO euo uey noA oq ebpuueo uo IO y eq ueo Goj depe eui 0 10joui joeu UOD Jey sjueuie e uo Me12S sieAup e qeobDueuoreju uong1o1 uoqqu suw3o
38. WANT TO START OR WISH TO BRUSH UP YOUR ASSEMBLER PROGRAMMING SKILLS THIS IS WHERE TO BEGIN I REMEMBER ATTENDING A COUPLE OF TALKS GIVEN BY LAURIE IN THE 1980 5 HAD THE PATIENCE OF UOB AND THAT KNACKs LIKE 96 TPI 80 TRACK TRACK O zorg TRACK 2 nin MATA NEW DATA OLO AND WHILE I M TELLING YOU ALL MY WOES ANOTHER SLIGHT DISAPPOINTMENT WAS WITH THE MACINKER IT SEEMS THAT THE MAIN RIBBON I WANTED TO RE INK FOR MY TANDY LPVII gt NEEDS A SPECIFIC RE INKER AND NOT THE UNIVERSAL ONE ANYWAYs DEE HAS PROMISED TO TRY AND REPLACE THE RIBBON IN THE CARTRIDGE AS SOON AS HER HAND IS BETTERe WHAT WOULD WE DO WITHOUT THESE WOMEN EH LUST IN CASE YOU HAVEN T COME ACROSS THE MACINKERs I VE REPRINTED ON PAGE 9 AND 19 ONE OF THEIR BROCHURES FROM THE 1986 S AND SO TO DETAILS OF THIS MOST GOOD TEACHERS OF INSPIRING ENTHUSIASM IN EVERYONE AROUND THERE S ALSO A COUPLE OF BASIC ARTICLE ON PRINTING LARGE NUMERALS AND ALSO ONE TO HELP IMPROVE YOUR KEYBOARD SKILLS WELL THAT ABOUT WRAPS UP THIS BIGGEST YET ISSUE I HOPE YOU FIND IT INFORMATIVE AND ENJOYABLE UUST TO WET YOUR APPETITE FOR THE UUNE 2013 EDITION HAS PROMISED AN ARTICLE ON THE MODEL 2000 THAT WILL BE A FIRST FOR TRSSBIT FOR ONE CAN T WAIT BUMPER EDITION TAKE CARE IAN MAVRIC HAS SENT A COUPLE OF ARTICLES THE DUSTY FIRS
39. a voice coil MFM hard drive it will always have an odd number as one platter surface is lost for head positioning data Case in point is the Microscience HH 1050 which has 3 platters 6 heads but only 5 heads are used and 1024 cylinders You can tell RSHARDx see my article from last issue the drive has 6 heads but when you format it every track will fail because the drive itself will not allow data to be written to the 6th head It s read only with positioning information for the other 5 heads A NICE SIDE EFFECT A somewhat unexpected side effect of upgrading your MFM hard drive to a newer one is typically in an increase in speed sometimes as much as 30 Here s why during the years 1981 1989 the technology of MFM drives increased rapidly from small 5Mb and 10Mb hard drives up to 40 70 and eventually 115Mb hard drives The MFM interface is inherently fast and the drive always spins at the same speed 3600 rpm so the higher capacity the drive the more densely packed the information on the platter so more is transferred per unit time Also the stepping speed of the heads increased as stepper motors became faster and more accurate and eventually gave way to voice coil actuation The Tandon TM602S and 503 are examples of early hard drive technology circa 1982 but installing a larger drive from the late 1980s will almost always result in a noticeable increase in speed CONCLUSION To my mind hard drives really bring out the
40. after the other and make notes about which keys don t work I was fortunate that in addition to all the keyboards in the machines Ivan supplied me with an additional new unused keyboard from a US TRS 80 Model 4D A quick test showed it to be perfect in way so it was given the nod to go in Ivan s pride and joy With a sharp CRT new board and re capped power supply I was on the way to putting together a nice machine Finding good disk drives can be a deal breaker for people doing their own TRS 80 restorations The Model III and 4 come with Texas Peripherals disk drives which are a cost reduced version of the Tandon TM100 1A disk drive Cost reduced meaning they are cheaply made and while most Tandon TM100 1A and 2A disk drives I find are still working the cheaper TPs don t stand the test of time very well this instance though Ivan supplied a large quantity of disk drives Lots had markings like formats but doesn t read or worked 1 4 87 etc but I did eventually find some disk drives which worked well and just needed some cleaning and a little re calibration installed a beige Teac FD 55BR 40 track double sided unit is drive 0 and a black Teac FD 55GFR 80 track double sided unit as drive 1 Once I m at this stage where the hardware has essentially been selected and tested the next step putting it all back together is where the fun starts Tandy made a really excellent set of Radio Shack Service Centre diagnostic disks
41. are available including LDOS 5 3 1 Newdos 80 2 5 and CP M 2 2 I have also tested DOSPLUS IV DOSPLUS 3 5 for the Model 3 as well as Newdos 86 and all seem to work flawlessly The hard drive image on the supplied SD card is configured as 6 partitions named HARDA HARDF Each partition having TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 44 140 cylinders 6 heads giving a total of 40 megs of storage With a little bit of work it is possible to max it out to 1024 cylinders and 8 heads giving a total of 64 megs Insert the SD card and power up the FreHD after a couple of seconds the green led will flash and she s good to go Place a BACKUP of the supplied boot floppy into drive 0 and press reset We can now remove the floppy and run the computer entirely from the FreHD Backing up data from the FreHD is as simple as inserting the SD card into a card reader connected to a PC All very quick and easy and no more wasting hours copying files to floppy Now while all this is fine and dandy the whole point of having a hard drive or a FreHD is so we don t have to play around with floppies especially boot floppies The boot rom on my 4P has been hacked to allow loading of the ModelA III rom image from either the hard drive or floppy and Adam Rubin s patches have been applied to LSDOS 6 3 1 to allow booting directly from the hard drive without the use of a floppy Naturally I wanted to see if I could get the to both load
42. are there just to confuse you they are known as the alternative set of registers and represent the fact that the Z80 is very nearly two microprocessors in one with a duplicate set of registers available for use if necessary Since Microsoft didn t find it necessary to use them to get the TRS80 to work I doubt if we will need them either So we are left with HL BC and DE These can be used as 6 independent 1 Byte 8 bit registers H L B C D and E or as 3 combined 16 bit ones depending on what you want them for The HL pair stands for High and L for Low tens and units if you like except the tens are two hundred and fifty sixes is the cleverest of the three and has a limited brain of it s own Liken it to the fingers right hand for H and left for L The others BC and DE are relatively dumb but we couldn t get along without them B is perhaps the most useful and has a great propensity for counting Just the thing for stepping through a program and keeping a count of the number of steps Unfortunately it s a little bit more complicated than just pressing the break key to stop in the middle of a machine code program and find out just what are the values held in the various registers but it can be done when using the de TRSSBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 17 bugging facilities that Zen offers us It is then that the X display becomes meaningful because it shows us just exactly what the Z80 was up to at the stag
43. bugger and getting er of 7813H This is racter displayed and popping DE a IY as n ither ar I suppose that there is really no need to be pushing being used in our programs back from taken for granted but note the value the next t byte in that it b for anything important whenever calling 2BH otherwise one day you WIL The fun starts I suppose is given the label Messag ut it should become second L be caught out with line 4 where the HL to take wit VIDEOUT is called VIDEOU complications of actually to OUTPUT There s enough up the characters pointed has done with them on wh is also of interes DB Define Bytes pseudo Message and the DEFB DE assemblers and allows long as they are separa Line 7 doesn t get outputting to the video to be getting on with just to by HL and checking af et t as we hav op This supercedes th Fine Byte nature 33R or 38B to save these two registers register h it on line 5 where involved with the that s le EE t picking ter OUTPUT ther or not to get some more used Zen s all purpose DEFM of the more primi the mixture of different operands as DEFine tive d by commas Also notice tha for each character in the DB statement there is a corresponding hexadecimal value generat ed in the o
44. by to check your answer One plus one equals zero with carry One plus zero plus carry equals zero with carry One plus zero plus carry equals zero with carry One plus zero plus carry equals zero with carry That s half of it done One plus zero plus carry equals zero with carry One plus zero plus carry equals zero with carry One plus zero plus carry equals zero with carry Remember that the minus sign is really just a Bit 1 lying on its side so the last one One plus zero plus carry equals zero with carry falling off the end advanced students might guess that it didn t really fall off it went into the Carry flag more about that later Answer 0000000 0 0 Dec 58 VOLUME 27 ISSUE 1 MARCH 2013 PAGE 19 So if adding 1 makes the original number 0 then the original number must have been 1 Get out of that OK I know it didn t look like minus one but I did warn you that the Z80 wasn t happy about it either The following is the way the Accumulator would store the number 128 if you wanted it to 1000000 0 ie 80 Hex Try adding 1 a hundred and twenty eight times Minor Diversion to talk about flags As we have a potentially dangerous situation here since a number in the A register could be treated as a large positive one between 121 and 255 or a smaller negative one we had better do some flag waving to check on where we are To help us is the friendly unassuming F register with a very useful flag
45. couple of good used disk drives from Ivan s collection of spare parts and before long the computer was booting up to TRSDOS 1 3 and running memory test routines Enough work for one afternoon so I called it a day The next day I ran memory testing routines for most of the day while I restored the trace cuts and re wiring Graham had done to the hi res graphics board The moment of truth was when I attempted to re connect the hi res board and loaded up Tandy s Service Centre diagnostic disk which has test patterns for the hi res board A pattern loaded up it was high resolution but none of the test patterns looked remotely like they should A closer look at the patterns that did show up displayed alternating black and white blocks interspersed with sections of what the pattern should have been Knowing that the memory on the hi res board is visible memory white blocks indicate a bit stuck high and a black block represents a bit stuck low Given the poor state of the main RAM in the Model III it was reasonable to suspect the RAM on the hi res board suffered the same fate and so replacing the memory chips on the hi res board cured the problem and displayed the proper test pattern I put the computer back together and was working on it a bit when I decided the brightness needed to be turned up a little so I reached under the computer where the brightness contrast controls are only to find the brightness control stuck solid I ve se
46. height and power setting again as it does in real life We like to think that we publish good programs Jumbo is outstanding It is available on tape or disk for 16K or 32K memory machines It is compatible with the Model Tandy Video Genie Genie and Genie machines 2 15 00 VAT 17 25 2 17 00 VAT 19 55 Plus 75p P amp P please MOLIMERX LTD A J HARDING MOLIMERX 1 BUCKHURST ROAD TOWN HALL SQUARE BEXHILL ON SEA EAST SUSSEX TEL 0424 220391 223636 TELEX 86736 SOTEX G TRS 80 amp VIDEO GENIE SOFTWARE CATALOGUE 1 00 refundable plus 1 postage TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 56
47. high order one low and in our case we have initialised them at zero When we test this routine we will discover the peculiar way the Z80 puts the contents of a register pair into memory In human terms it appears to be back to front i e the most significant byte comes second when displayed left to right A better way to think of it though is to realise that the highest order most significant byte goes into the highest address of the two bytes of storage and the lowest least significant byte goes into the lowest address Right oh assemble and jump to 7800H with a breakpoint at 7818H or 780EH if you want to stop half way key in any number you want and then check with Q7831H on what has been stored at the location labelled Quantity Now that we ve assembled some programs with a reasonable number of labels in them let s look at something else Zen has got for us The first is the simple sorted Symbol Table listing which tabulates all the labels we have used and their hexadecimal values Label value Label value Label value Label value BS 0008 CR OOOD CONVERT 7833 CONVERTEND 7852 CHECKNUM 786D HOWMANY 7819 KEYIN2 7857 KEYSCAN 789C NUMBUFF 782C NUMBERIN 7855 NOTFUL 787D NUMBVDU 7881 OUTPUT 7892 QUANTITY 7831 TIMESTEN 783F VI DEOUT 7886 TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 18 With the later versions of Zen there is a cross reference listing capability that lists every label in the symbol table with its valu
48. honesty the answer must be not quite but we don t want to run before we know which direction we should be walking Lets prove that the program actually works before we go any further To do that with E m or M 80 or very nearly any other assembler the technique is to assemble to cassette or disc go back to the operating system system load the object code power up Debug or Supermon and jump to your program start address Now that is just too much like HARD WORK so we will get Zen to do it all for us First we need to tell Zen that the object code bytes should be loaded into memory as they are evaluated during assembly To do this we need to insert one line of code into our source file between line 1 and 2 Here s how Goto line 2 T E for Top then D1 E for Down 1 Zen should be displaying line 2 Key E E to enter the editor and we get the prompt 2 Key LOAD 7800H E followed by the full stop E Assemble the program again using if you have a printer the E option so that you can frame the printout for posterity as the your first working machine code program The result of the assembly should look exactly as before except the line 2 to 13 now have the numbers 3 to 14 and there s the new line 2 LOAD 7800H To check that the code is in memory use Zen s Query command TRS BIT VOLUME 27 ISSUE 22 JUNE 2013 PAGE 11 Q7800H lt gt You should get 7800 21 00 3 01 00 04 36 Al 6 Lm 7
49. if you want to use your floppy DOS and not the hard drive you just leave the hard drive switched off and boot your floppy disk and play a round of Frogger or Zaxxon NOT SO with the Model I the adapter will not allow your Model I to boot unless the hard drive is switched on and up to speed So if you want to play a floppy only game you have two choices power up the hard drive and let it sit there humming away next to you or disconnect it from the Expansion Interface The first is a waste of electricity and the 2nd is just inconvenient The other one stems from a problem which I m still trying to understand but seems to manifest itself as an inability to properly write the hard drive configuration file on Model Is which use the later design Expansion Interface Let me try to explain it When I bought my Model I it came with the early design EI the one with the buffer box When I bought my hard drive and read the instructions it clearly stated that if you had a very early EI it needed to be modified to use the buffer box which in turn made it compatible with the hard drive Since my EI had already been modified I just plugged in the hard drive and off it ran Some years later I tried to use my hard drive on a Model I with the later design non buffer box EI and found that if you booted with a boot disk created with the early EI it worked but if you attempted to create a boot disk with the later EI it wouldn t work properly No bi
50. in the Mode However no socket changes are necessary make the modifications All VOLUME 7 ISSUE 94 DECEMBER 2913 that is required i to lift certain pins on the new RAMS pins and 8 so that the pins Go m make contact with he sackets These pins which were lifted or bent up will be wire wrapped for Their new con nections With some types of RAMS few rmantaciurers require mat pin 1 be connected lo 5 vols Be careful hare because on the existing sockets ihe TRE BD Wedel board pin 1 i 5 volts in eur modification such tyres of the RAM must have ihe pin lifted so that it is not engaged in ihe socket Thay must be lifted and than siung tegetbar and connecigd to the 5 vost line The chips we used do nof pin T con nected intemally and pen 1 is nol con to 5 wolis so this was moi a problem in ther modifica tion shown in Eher CH course it would be remiss on pur pari if we teli vou to be caredul of the marsitgcturer and then not tall you where we gol our chips Here is the supplier Microprocessors Unlimited P O Box BOBO Beggs Oklahoma 74421 phona 916 267 4795 Tha chips ara designated 220 OKI plastic dynamic RAMS When we got aur they were about 5 00 each Required Modifications We could do the modifications in a siep by step manner bul lhe changes are simple The project jusi quires some con H is assumed thal any
51. install DSK DCT on the TRS 80 using the following LSDOS System command SYSTEM DRIVE x DISABLE DRIVER DSK DCT Reply to the prompt with the name of the appropriate DSK image file DSK DCT will allow you to load any DSK image file saved on the SD card and have it treated as a normal floppy which can then be copied to a physical floppy using DISKCOPY CMD After the failure of the old hard drive I was convinced that my 4P would be a floppy only machine but the FreHD funny name has put some life back in the old beast If anything it is now a faster more versatile computer and jobs that were previously a major pain have become a very simple task Finally many many thanks must go to all the people that freely contribute their time and expertise in keeping these machines alive long after their use by date Gazza gazzajhGoptusnet com au TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 47 MAV S BELIEVE NOT by Ian Mavric SYDTRUG S MODEL I COMPUTER Sydtrug the Sydney TRS 80 and MS DOS user s group were in the process of moving premises and found they had a lot of old TRS 80 equipment software and manuals which I managed to acquire You find the most unique things this way and under a dust cover I found what seems to me to be the most modified TRS 80 Model I that I have ever seen Looking at the photos I can see the following modifications Orcim Systems hi resolution graphics character genera
52. is needed a Basic program is a dummy line to take the characters a string As each character is inserted the actual graphic block is shown on the screen Just think what you can do with your program with various lines containing this facility Unlock the entire graphics potential of your Tandy TRS 80 or Video Genie and see what your computer is really capable of Ka Kansas City Systems Unit 3 Sutton Springs Wood Chesterfield Derbys Tel 0246 850357 TRSBBIT VOLUME 27 ISSUE 21 MARCH 2013 PAGE 18 Chapter 3 Negative Numbers Negative numbers are a concept that the Z80 would rather do without Either there s a 1 there in which case something is there or there s a 0 and there s nothing there The preposterous idea that there is less than something there is just too ridiculous But since we humans insist on using this hair brained idea then the Z80 tries its best to comply Picture the number 255 Dec or OFF Hex in binary notation remembering that that leading zero is just to stop the computer thinking you re swearing at it OFF Hex Binary 1111 1111 Beautiful Since we always write our minus signs on the left of a number lets turf the leftmost bit over on its side like this 111 1111 Now we are getting somewhere That s a negative number if ever I saw one but what is it The easy way to find out is to add 1 to it and see what happens Ready Left blank for you to fill in Stand
53. memory command so Zen started by printing the value 1650 and then examined the TRS80 s memory starting at 1650 and displaying in hex each byte from 1650 to 1658 The right hand half of the display is an Ascii representation of the same 8 bytes of memory but shown so that the bytes whose values are greater than 127 and not normally considered as displayable Ascii art depicted in two formats for maximum information On the extreme right is the academically correct display where any bytes greater than 127 are shown as full stops On the left is a much more TRS BIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 14 interesting presentation as all the bytes are displayed as recognisable letters This conversion from unprintable to printable is achieved by Zen subtracting the value 128 from any number greater than 127 Now this is no accident or defect in the ROM because if we look closely at the letters we see that what is shown is a listing of some of BASIC s instruction codes such as END FOR RESET etc except that there are no spaces in between This is a look up table used by Level2 BASIC to check on the spelling in your Basic program and if what you key in doesn t match any of the words in the table you get a syntax error By squashing all the words together Microsoft saved themselves quite a lot of ROM that would been just spaces but they then had to figure out a way of knowing when they had come to the end of one keyword and the start o
54. of all make the effort to comprehend the way information be it program or data is stored in the computer and the conventions used to present it at the human interface Right down at rock bottom most if not all computers store and evaluate numbers in simple binary 0 s 1 s However most of the time we and the computer operate not with these individual Bits but with eight of them at a time called Bytes Invariably however just to break the first rule 58 VOLUME 27 ISSUE 01 MARCH 2013 PAGE 12 straight away and purely for our convenience these bytes are split into half bytes called nibbles so that we can avoid having to do mental arithmetic to base 256 By thinking in terms of 4 bits at a time the powers at be have forced us into straining the brain and understanding hexadecimal arithmetic base 16 which isn t really too bad and not much worse than feet and inches Consider the eight bits below with their numeric values when the bit is set i e equal to 1 rather than 0 Bit number 7 6 5 4 3 2 1 0 Decimal val 128 64 32 16 8 4 2 1 Hex value 80 40 20 10 08 04 02 01 Now it doesn t take an overdose of grey matter to see that the values of bits 0 to 3 can be represented by the right hand half of two hexadecimal digits and the bits 4 to 7 by the left hand one Even if all the bits 0 to 3 were set giving a value of 1 2 4 8 15 this would not exceed the ability of hexadecimal notation where 15 is r
55. of danger An enthralling game with excellent graphics personalisation of highest scores and points bonuses One of its best features is the crisp and immediate control the player has over the manoeuvreability of his ship which includes diagonal movement Machine language of course for speed A matter of taste but we think it beats Invaders and Asteroids Suitable for TRS 80 Models and 1 and all Genie models Tape 16K 13 00 V A T 14 95 16 00 V A T 18 40 MOLIMERX LTD J HARDING MOLIMERX 1 BUCKHURST ROAD TOWN HALL SQUARE BEXHILL ON SEA EAST SUSSEX TEL 0424 220391 223636 TELEX 86736 SOTEX G TRS 80 amp VIDEO GENIE SOFTWARE CATALOGUE 1 00 refundable plus 1 postage w TRSSBIT VOLUME 7 ISSUE 2 JUNE 2913 PAGE 36 TRSSBIT WELCOME ONE AND ALL TO THE SEPTEMBER 2013 EDITION THERE S SO MANY EXCITING THINGS TO REPORT I LL GET STRAIGHT DOWN TO THE NITTY GRITTY MAV AND COLLEAGUES HAVE BEEN WORKING HARD TO PUSH THE DEVELOPMENT OF FREHD FORWARD TO SUCH A POINT THAT AS AT PUBLICATION THE 1 3 AND VERSIONS ARE UP AND RUNNING THEY ARE AVAILABLE FROM MAV S WEBSITE IN EITHER KIT FORM OR COMPLETE AND READY TO USE I UNDERSTAND THAT A MOD IS REQUIRED FOR THE 1 VERSION BUT THE OTHERS JUST PLUG IN AND GO THE MUP VERSION IS EVEN SELF BOOTING MAV ALSO CAN SUPPLY ANY NECESSARY ADDITIONAL CABLES TOO
56. say It certainly looks impressive but what does it do There s a definitive answer to that question that goes back to time immemorial or at least to Babbage and it is Well it doesn t do anything yet but wait till I get the bugs out Third Simple Rule Assembly language programming isn t a bit like BASIC Don t cry about it there s nothing anybody can do and remember you couldn t understand ON ERROR GOTO and PRINT USING once Sooner or later we are going to want to change a Hex number into decimal so lets do it with 7800H 7 4096 28672 800H 8 256 2048 OOH 0 16 0 OH 0 1 0 7 8 0 0 Hex 30720 Decimal Now that wasn t too hard was it I leave you to work out for yourself how to do get back from decimal to hex There s a tradition build up with the TRS80 that the first machine code program example should be whiting out the screen in no time at all so just to be that bit different we will fill the video with a chequer board pattern In order to achieve this laudable objective we need to know how the video is connected to the computer AND I don t mean that silly little plug on the end of a bit of wire TRSBBIT VOLUME 27 ISSUE 2 JUNE 2013 PAGE 6 Fourth simple rule Most apparently straight forward bits of English don t mean what they used to mean when talking about computers What we mean is the logical connection between the Z80 and the video character generator Fortuna
57. to give us an address for the breakpoint when we test the routine Assemble the program and check with Q7800H that it has loaded into memory Now before we jump or goto 7800H to test it use X to examine the registers first and pay particular attention to the values of AF and DE Now jump to 7800H and set a breakpoint at 7805H Key X again to examine the registers and the video should look like this 2 gt HL DE BC AF RI IX LY SP PC Flags 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 5627 402D Z gt J7800H Brkpnt gt 7805H 2 gt HL DE BC AF RI IX IY SO PC Flags 0000 401D 0000 2A20 7200 0000 0000 0000 0000 0000 0000 5627 7805 Well apart from the fact that only the most recent disc version of Zen has the Flag register decoding what are we to make of this Firstly the routine worked and if we look hard enough we can see that the got printed at the cursor position following the last input before Zen jumped to our program Which since our last keystroke was an lt Enter gt or carriage return was at the start of the line after the Brkpnt gt 7805H Secondly the AF DE PC and R registers came back with different values to those they initially had on leaving Zen The A register was of course altered by our program but what about the others
58. will be displayed tes As bed bits are found the stars wil be replaced by letter X so erreur Bit 7 is leftmost in this dis play and bit 0 is to the right It wil continuously loop exercis ing this one address just as the Babyroot program exercised the who of the memory After given period of time the bad bas should be indicated by an X youll need to buy placement 4116 RAMs 8 to 15 for each bad bit pos tion Dynamic RAMs are curious Gevices If you don know how to handie these sensitive MOS devices find out Look in Popv lar Electronics on data sheets in books ask a friend or what ever bul don t proceed until you know how to handie them And put your cats in the bathroom For greatest satety use a static ual of RAM expansion instruc tion sheet Open the case find the RAM s corresponding to the bad bitis Pull the RAM s Re place each wiih a new 4116 and run Babyroot again If the error gone and should be you re set f not double check your work making sure you ve re placed the correct RAM Switch RAMs See if the bad bit changes position Go down the line You may even have a bad new RAM H you re desperate call me know the feeling of sitting weke M 3 am wondering whether or not should turn my TRSANO into flower pot IW try 10 help you with your diagnosis 1 hope the program runs for days without turning up bad bit Good luck a RESS
59. would require a re design of the board and result in two products on the market Most people who own a Model I also have a Model 4 and wanted to use the FreHD on either machine as they saw fit It made more sense to use the 26 1132 adapter so work was taken to make FreHD work on the Model I that way Without boring you with details by changing one chip on the emulator U3 to a 74LS245 the FreHD works on a Model I with the adapter So we had a workable solution but the same issue whereby we now needed those hard drive adapters again Fortunately Bill Buzbee amp Larry Fosdick had done all the work in 1992 drawing up the schematic for the 26 1132 adapter and Fred Vecoven designed a small PCB which does the job very nicely named it the Benson box after the worlds most prolific collector hoarder of TRS 80 memorabilia 4 415 4 Adapter TT IR em AERE is VE 22 a TRSBBIT VOLUME 07 ISSUE 24 DECEMBER 2813 PAGE 27 VINTAGE DRIVER SOFTWARE As with the Model III and 4 there are a number of different hard disk drivers out there and they all do pretty much the same thing the same way as each other except that later drivers offer much more flexibility Early drivers were called TRSHD1 DCT and only supported the old 5 Meg hard drive They work fine if you only want 5 megabytes on your hard drive or FreHD Since most people want to utilise more than 5 megabytes an article in
60. 0 DATA 35 11 120 177 32 248 193 201 80 rest of program There s a 1 in 5000 chance that this routine would fail should the result of VARPTR US 0 X be greater than 32767 and what we ought to do is test it first before executing the Poke but I leave that to you When line 80 is reached the whole of our machine code program is safely in memory and we now set up a subroutine at say line 1000 which can be called at any stage in the main Basic program Disc users have it easy in setting up USR routines and their subroutine would be 1000 DEFUSR VARPTR US 0O 1010 X USR 0 RETURN Level 2 programmers have a bit more work to do which involves as you might have guessed dividing the VARPTR value by 256 and Poking the result and the remainder in the USR vectors given in the manual TRSSBIT VOLUME 07 ISSUE 02 JUNE 29013 PAGE 19 1000 X INT VARPTR 05 0 256 1002 PORE 16527 X 1004 POKE 16526e VARPTR US 0 256 X 1010 X USR O RETURN It is necessary for us to set up the USR address every time we need to access this routine due to Basic s memory allocation procedures mentioned earlier GAMISIET 6O The World s No l Microcomputer Chess Program by Wim Rens Gambiet 80 was the most successful commercially available Chess Program at the official World Microcomputer Chess Championship in London September 1980 FACILITIES INCLUDE 6levels of play from speed chess to tournament level Graphic board
61. 01 16 4 20 E 4 10 4 14 0 15 1 16 0 1 0 E with carry TRS BBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 16 Since there isn t any room in the A register remember there s just 8 bits to store the information about the carry condition we have to have another register alongside where interesting things such as Zero Carry Positive or Negative states are brought to the Z80 s attention As this register is effectively waving flags at or because of the Accumulator it is known as the Flag or F register These two registers are the best of friends and very little activity in the A register is not known about in the F However there is one very important exception and that is the simple loading of data into the A register F couldn t care a fig he s only bothered about exiting events like adds subtracts and compares That s sorted the brain out where are the fingers and toes Well theses are the other registers and we have quite a few Just to make life simple forget completely about RI that s something to do with refresh and interrupts all very nasty forget nearly completely about IX and IY and just put to one side for the moment SP this stands for stack pointer very important PC stands for program counter and is simply the address of the next byte of machine code that the 780 would execute That leaves HL BC and DE with a repeat underneath alongside another AF Those on the bottom line
62. 04 DECEMBER 2013 PAGE 21 0060H Delay Decrements BC until 0 then returns Uses just BC and AF registers 0072H Basic Ready Jump to 72H instead of IA19H Jumping to 1A19 is OK if you ve tidied everything up first If you haven t and you want to get back to Basic from a System load or other m c routine 72H does all the housekeeping for you 01C9H Screen clear On model 3 all registers altered Usually switches cursor off on Model 1 01F8H Cassette Off Switches cassette off 0212H Cassette On Switches cassette on It is probably best to XOR A before calling either of these I don t know how the second cassette via the expansion interface is addressed 022CH Blink Flashes the e 0235H Byte in Reads byte from cassette into A register 0264H Byte out Outputs byte in A register to tape 0287H Write sync Outputs the leader and sync byte to tape Uses BC registers 0296H Reads sync Reads the leader and sync byte from tape 0314H Address read Reads two bytes into HL Used for the load address in system tapes 37E8H Printer addr Model 1 parallel printer connected here Model 3 puts printer status here For Bit 7 0 Not busy both Bit 6 0 Paper OK Model 1 Bit 5 1 Device select whatever that means amp Model 3 Bit 4 1 No fault TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 22 Keyboard Matrix Address BitO Bit1l Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 3801 A B D E F G 3802 H I J K L M N 3804 P
63. 40AC mains On Off Print Select Paper Advance Empty Controls Size 10 x 131 x 44 Weight 10168 Ideal for Home or Small Business use LIMITED QUANTITY DON T DELAY Brand new boxed fully guaranteed list price of Complete with Full documentation machine 459 95 inc connector amp Printing Paper OUR PRICE HALF PRICE OFFER 00 1 95 inc of VAT Just Plug in and it s ready to go POST PAID AS RECOMMENDED BY COMPUTING TODAY MARCH MAY 1980 Your London amp National Nascom Distributor COMPUTER Fw Export Orders deduct VAT but add 5 carriage BROCHURE xS TELS Henrys Official Export amp Educational Orders welcome pner Division Our Telex 262284 Mono Ref 1400 Transonics FREE STAMP 404 Edgwere Wa England TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 41 ASK MAV MODEL 4 HARDWARE QUESTIONS by Ian Mavric Is Q I have a 16K cassette based Model 4 how do I upgrade it with disk drives A To upgrade a Model 4 disk drives in addition to the disk drives themselves you need the following disk drive towers disk controller FDC disk drive cable motherboard to FDC cable 2nd power supply power cables for the FDC and each disk drive grounding cables and assorted screws and washers to mount the new parts Since a 16K disk based computer makes no sense you also need 8x 4164 Ram chips to upgrade the computer to 64K While the computer is open you may as well upgrade it to 128K s
64. 6 10 Generate the configuration file on the boot floppy for the hard disk SYSGEN DRIVE 6 NEXT TIME I will discuss how to fix or upgrade a hard drive by replacing the original MFM with a different one and what to do with those 3 wires janm trs 80 com REFERENCES 1 EXPANDED DISCUSSION ON TRS 80 MODEL III AND 4 HARD DRIVES TRS8Bit December 2012 pp 8 14 2 http tim mann org trs80 doc rshard pdf 3 http www youtube com watch v 0 JbYGis0a8 TRSBBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 32 TRSSBIT FLAMING JUNE ARRIVES TOGETHER WITH THE LATEST EDITION OF TRSSBIT BOTH I HOPE PUTTING A SMILE ON YOUR FACES WELCOME TO WHAT IS TURNING OUT TO BE A MOST EXCITING YEAR FIRST I D LIKE TO MENTION WHAT I CONSIDER TO BE THE REALLY EXCITING NEWS OF 2 BRILLIANT PIECES OF HARDWARE JUST DEVELOPED WHICH ARE AVAILABLE FROM MAV S WEBSITE THE FIRST IS NEW DOUBLE POWER SUPPLY WHICH MAV AND DAVID COOPER HAVE DEVELOPED FOR THE MODEL 1 NO MORE PANICKING WHEN THE OLD POWER BRICK DIES IT S MADE TO SIT NEATLY IN THE EXPANSION INTERFACE USING THE SPACE TAKEN BY THE 2 OLD POWER SUPPLIES THE SECOND IS A VIRTUAL HARD DISK FOR THE MODEL 3 OR THE MODEL 4 NEAT PIECE OF ELECTRONIC ENGINEERING PLUGS INTO YOUR M3 OR M4 VIA THE SOWAY CONNECTOR AND COMBINED mmt o c In this issue of TNMOC SERIA PRINTER DRIVER TRS BIT VOLUME 7 ISSUE 2 JUNE 2013 WITH AN SD CA
65. 640 1660 1680 PRINT INVALID SELECTION PRINT GOTO 1280 BR BR 1 B B 150 IF lt gt 0 THEN 1380 GOTO 1500 BR BR 1 B B 2 B lt gt 600 THEN 1440 BR BR 4 FOR I 1 TO BR READ D NEXT DH INT D 256 DL D 256 DH Y POKE BAUD RATE CODE POKE MS 24 DL POKE MS 25 DH POKE MS 66 DL POKE MS 67 DH POKE MS 76 DL POKE MS 77 DH INPUT ADD LF AFTER CR 05 1700 IF THEN 1800 1720 IF QS lt gt N THEN 1680 1740 1780 1800 FOR I 1 TO 4 POKE 5 48 1 0 NEXT INPUT NUMBER OF NULLS 0 127 N 1820 IF N 0 OR N gt 127 THEN 1800 1840 1880 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2120 POKE MS 42 INT N 1 END Y MACHINE LANGUAGE PRINT PROGRAM DATA 243 121 254 13 40 3 254 32 216 245 229 197 6 9 55 245 245 33 1 952 205 33 2 93 222 0 43 124 181 32 DATA 251 241 91 945 28 19 33 0 252 24 19 14 2 175 13 40 DATA 25 24 219 62 10 94 215 24 47 198 0 33 142527205738 DATA 25050 93422950449 124 101 324250 16 2 02 1190220 DATA 203 14 40 11 33 0 252 205 93 2 21 122 17932525 DATA 241 241 254 13 40 198 183 40 197 193 225 241 201 Y BAUD RATE TABLE DATA 615 450 222 146 108 51 23 8 1 END OF PROGRAM wht TRS BIT VOLUME 27 ISSUE ULM EU debes Hoe IN MAV S RETROSPECTIVE WORKSHOP THE TANDY TRS 80 MODEL 2000 Was it the finest TRS 80 ever by
66. 808 23 78 00 C2 06 78 4 Os 7810 79 00 2 06 78 xx xx y X 0 figures aren t important except that if we don t intercept the Z80 after its done our program then they are what will happen next The Ascii representation on the right will be different as Scripsit can t print the graphics that you get on your video To execute the program we want to instruct Zen to Jump or Goto the address 7800 Hex and let the program do its thing and when address 7816 Hex is reached to return to Zen There s a minor complication here as very early versions of Zen used the single command letter G whence you were then prompted for the address later versions included the address with the G Goto like this G7800H E and finally the versions of Zen with the Global replace facility use the command format J7800H E Jump Since you can all refer to your manuals I don t expect that this will be too problematical Depending on your version key one of the following J7800H E or G7800H E or G E followed by 7800H E Zen will then ask for a Breakpoint key 7816H E and faster than the eye can blink your video will be filled with spots Unfortunately if you didn t buy your Zen from me the screen will even more quickly be cleared so that might not catch it but you know the answer to that Before we dash off and celebrate lets write the source code to tape or disc
67. AC 58 VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 27 across points and B and 17 19VDC across points C and D D being ground and C being 17 19VDC Make up your power cables to the TRS 80 and test one last time and you should be in business ABCD 1 x MOUNTING IN THE EXPANSION INTERFACE Dean noted if you remove the black power supply holder from the EI some common sense will show that a small amount of carpentry is needed to mount the power supply in the compartment NEXT TIME I talk about FreHD the Hard Drive Emulator for the Model I III 4 4P ianmGtrs 80 com TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 28 IVAN KENNEDY S MODEL IIIs by Mavric contributing writer This article first appeared in SYDTRUG News Back in February Ivan emailed me saying he had a number of old TRS 80 systems which he would like to get fixed and asked if I was up to the task After a few more details were sent back and forth between Ivan and I we made plans for a visit to my workshop with a Subaru Forester full of TRS 80s The actual count was 6 Model 4s 3 Model IIIs a Model 1 system a Model 4P portable TRS 80 a Tandy 200 notebook and boxes or spare parts and a small consignment of software My briefing was simple fix as many as I could before Ivan had to return to Sydney two weeks later I first had a look at the Model III computers two looked complete a 16K cassette based machine and a very
68. ACTED ME REGARDING THE M1 INTERNAL UPGRADE USING 4164 CHIPS IT SEEMS THERE WAS AT LEAST 2 E E ar of THERON INFOR VERSIONS AND DETAILS OF THE ONE IN CQ MAGAZINE SENT TO ME BY LARRY KRAEMER ARE IN THIS ISSUE IT ALSO REMINDED LARRY OF A MEMORY CHECKING PROGRAM WHICH FIRST APPEARED IN 89 HE REMEMBERED AMENDING IT FOR THE MODEL 3 SO IN TRUE TRSSBIT FASHION BOTH THE PROGRAMS ARE FEATURED IN THIS ISSUE LARRY ALSO SENT DETAILS OF REPLACING THE INTERNAL ROM S WITH EPROMSe WITH HIS PERMISSION AND SUPPORT DETAILS SHOULD APPEAR IN THE MARCH 2914 ISSUE STUFF ALREADY IN THE PIPELINE FOR OUT 8TH YEAR DUE TO THE SIZE OF THIS ISSUE I LL KEEP THESE NOTES ON THE SHORT SIDE FULL CONTENTS LISTINGs JUST FOR THIS ISSUE NOW APPEARS PAGE 2 THE UK S EBAY HAS BEEN REASONABLY BUSY OVER THE LAST 3 MONTHS MUCH OF IT WITH VERY SILLY PRICES THOUGH CIE 50 FOR A CASSETTE GAME HOWEVER A VIDEO GENIE FETCHING 160 WAS NICE TO SEE WELL AT 56 PAGES THIS IS THE BIGGEST AND I HOPE YOU LL AGREE BEST EDITION YET PLEASE KEEP SENDING IN ANY TANDY RELATED ARTICLE FOR WHAT ID ABOUT TO BECOME OUR 6TH YEAR BYE FOR NOW AND HAPPY CHRISTMAS EVERYONE DUSTY 58 VOLUME 27 ISSUE 4 DECEMBER 2013 PAGE 1 PAGE PAGE PAGE PAGE PAGE PAGE PAGE PAGE PAGE PAGE PAGE PAGE 3 5 amp 24 30 32 34
69. ASIC program that has the line 100 LET Y 4 3 3 and imagine that we stopped the program with the Break key just as the 280 had finished working out that line We could then tell the computer to PRINT Y and get the answer 13 Obviously the variable Y has had it s value stored somewhere after it was evaluated and of course that somewhere is in a few bytes of RAM that BASIC has allocated from the memory that was not needed for other things Now in the middle of processing that line of code the computer had first of all to get the number 4 on one hand then calculate 3 times 3 probably using it s toes add the two numbers together somebody else s toes check whether there were any more sums do and then and only then put the result into RAM Thus releasing the fingers toes and brain for the next sum In the Z80 chip the arithmetical brain is known as the Accumulator or register where any numbers in the range 0 to 255 can be added subtracted compared or fiddled about with Since the A register can only hold numbers up to the value 255 consider what will happen if the Z80 tries to evaluate the sum 250 20 The result is like adding say 95 and 8 pence We get 3 pence and an overflow or carry of 1 into the pounds The result of 250 20 in the Z80 is 14 with carry i e 250 20 270 too big therefore 270 256 14 Carry the same in hexadecimal Carry Sixteens Units F A 15 16 10 250 add 1 4
70. ATEST UPGRADE MAV S BELIEVE IT OR NOT IAN MAVRIC MAV COMES UP WITH A REAL MODEL 1 FIND BABYROOT DENNIS BATHORY KITSZ amp LARRY KRAEMER THE ORIGINAL ARTICLE BY DENNIS APPEARED IN S0MICROCOMPUTING AND WAS AMENDED BY LARRY FOR THE MODEL 3 TRSBBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 2 WATERMARKING BASIC PROGRAMS AJ HARDING I BELIEVE THIS ARTICLE FIRST APPEARED IN THE MOLIMERX CATALOGUE YOU WOULD BE SURPRISED AT THE AMOUNT OF FLAK I GET FROM CUSTOMERS FOR DEVOTING TOO MUCH TIME TO TAPE OWNERS AND CONTRARY WISE TO DISK OWNERS I WILL TRY AND CONCENTRATE ON ONE MATTER WHICH APPLIES TO BOTH AND 15 I ALWAYS THINK A RATHER GLAMOROUS TIP IT IS A METHOD WHEREBY A LINE CAN BE HIDDEN IN THE PROGRAM SO THAT WHEN THAT PROGRAM IS LISTED A FALSE LINE IS SHOWN IN FACT ANY OF YOU WHO BOUGHT OUR VERY EARLY PROGRAMS CIRCA 1978779 MAY HAVE COME ACROSS THE ANOMALY WHICH I AM GOING TO DESCRIBE BECAUSE AT ONE TIME WE DID USE IT AS A METHOD OF PROTECTING OUR SOFTWARE IT DOES NOT IN ANY WAY HINDER THE RUNNING OR COPYING OF A PROGRAM WHAT IT DOES DO IF IT IS NOT SPOTTED BY THE USER IS TO SUCCESSFULLY PROVE BEYOND ALL DOUBT THAT THE PROGRAM EMANATED ORIGINALLY FROM A PARTICULAR SOURCE IN OTHER WORDS IF SOMEBODY ILLEGALLY COPIES A PROGRAM THEN IF IT CONTAINS THIS WATERMARK THE TRUE OWNER CAN ALWAYS PROVE THAT A COPY WHICH HE COMES ACROSS LATER IS ILLEGAL SOMEWHAT LIKE SHUTTING TH
71. BC 1024 4 LOOP LD HL 161 E poke HL 161 5 INC HL E HL 1 6 DEC BC lt E gt BC BC 1 7 LD A H lt E gt if 8 CP 0 lt E gt BC 9 JP NZ LOOP lt E gt lt 10 LD A C E gt 11 CP 0 lt E gt 0 12 JP NZ LOOP lt E gt GOTO 13 END lt E gt 14 E The full stop tells Zen that we have come to the end and there s no more text input Zen ignores the full stop and switches control back to the command level Let s step through the program nice and gently to see what we ve done forgetting all about ORGS and ENDS for the time being 2 The LD instruction loads the HL register pair with the value 15360 which is the address of the top left hand corner of the video The LD part of the instruction is known as the OPCODE and the 15360 part is the OPERAND TRSBBIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 8 3 Likewise BC becomes 1024 which is our Byte Count 4 This is the tricky line LOOP is a label LOOP because it has a after it LD we know means load but what does HL imply Well its beautifully simple it needs to be once you get the hang of it HL by itself means the register pair HL HL means the byte in memory that HL is looking at so for the first time round HL 15360 and the load instruction means that particular byte next time round it will be 15361 etc 161 is simply the value of the graphics character that is to be loaded into the byte pointed to by HL 5 amp 6 Add one I
72. CAD but along with not many people buying the 2000 software companies lost interest in patching their programs for the 2000 April 1984 Tandy recognising the problem had an emergency meeting with its computer design teams and laid down the plans for a new project August which was to be a properly PC compatible computer that was much cheaper and be ready to announce in four months and on the shelf in six We know it as the original Tandy 1000 Those who have used the Tandy 2000 often have favourable memories of it and indeed I was mightily impressed by it when I got mine I didn t see it as a replacement for the Model 4 that wasn t until later on when the Tandy 1000 came along and it was clear from the pricing that the 1000 was TRSSBIT VOLUME 27 ISSUE 62 JUNE 2013 PAGE 31 going to impact on Model 4 sales The 2000 was always expensive beast A basic dual drive Tandy 2000 with 128K could be had for a modest A4450 but you could easily spend over A10 000 by the time you got the fully expanded Tandy 2000HD upgraded it to 768K hi resolution graphics colour monitor etc It never seemed to be a serious threat to the A2299 Model 4 the jobs both computers excelled at were vastly different In my study of the history of Radio Shack and its computing products and their place in microcomputing I found some interesting titbits of information about the TRS 80 Model 5 obviously planned as a replacement for the
73. CAN TURN OUT A BIT LIKE TOPSIE BUT THEY ARE SUCH GREAT FUN DON T FORGETs TO CHANGE THE PRINT TO LPRINT WHEN NEEDED 828972 dadaa 9090 0000 dala 400000 dadaa 4 a d d al al a d d 4 al al dadaa 29090 0000 24404 d ddadda a a d 4 al 1 a d al al dadaa 209090 40000 24404 d ddadda READY gt 10 LLS DBTR alaq d 9 gera 2 53271444441 2222222133 12211331331444133312215311221441135333314414411441331 1 0 NEAT INPUTRS CELEN CR YA 12072 12205 EEHERTEPRIBTIHERT Combine accurate flight characteristics with the best in animation graphics and you ll have SubLOGIC s T80 FS1 Flight Simulator for the TRS 8O SubLOGIC s T80 FS1 is the smooth realistic ana ial Featu simulator that gives you a r 3 D s out of the cockpit view of flig Maxi een ansfer keyboard input That to fast animation and accurate repre Constant feedback cassette loader sentation of flight the non oao can now learn contri includi ing take offs and Hardware Requi IS pilo ots will recog adio Shack TRS 80 qp Ms des morougniy s ner explore the 16K memory vimos s characteri Nothing else C sepia idein ve red flight der n the excitin riti A x D Aeri al Battle Ga inclut ed in package Destroy the lesan s fuel
74. D FOR YEARS AND I THOUGHT I COULD REFER TO IT IF AND WHEN NEEDED FOR INSTANCE LINE 199 IS THE PET EQUIVALENT OF CLS LOW AND BEHOLD IT DIDN T TAKE TOO LONG AND TURNED OUT TO BE QUITE NICE LITTLE PROGRAM THE ONLY COSMETIC CHANGE I THOUGHT MIGHT BE REQUIRED TO REDUCE THE PRINT MATRIX FROM 6X7 TO 5XT TO GIVE A MUCH MORE BALANCED DISPLAY ON MY WAS THIS SEEMED MODEL 1l THEN THE USUAL THOUGHT CROSSED MY MIND I WONDER IF I WOULD BE ABLE TO MAKE IT INTO A ONE LINERe THERE CERTAINLY WOULDN T BE ENOUGH ROOM FOR ALL THOSE DATA STATEMENTS THOSE PESKY COMMAS TAKE UP FAR TOO MUCH ROOM SO IT WAS GOING TO NEED A COMPLETE RE THINK AND RE WRITE TRS BIT VOLUME 27 ISSUE l MARCH 2913 PAGE 3 16 CLS DIMAC H CH 38 DATA X 48 JH DATA F RIZITOS REARDASCID PA DATA 4 444 410 Se se Se See Sele sesedecece de dese de le x 88 DATAd d d 1522273 a8 ATAL c ro de secede dececeledede liri rbi 188 DATAL d d de Se Sel 116 FO RIZ1TO B READAS I HEAT 128 INPUTS 138 FORT 1TOFtPRINTASCAC ARS I 148 GOTO uw oc DECIDED INSTEAD OF BUILDING AN ARRAY OF x INFORMATION FOR THE FORMATION OF THE CHARACTERS x I WOULD PLACE IT ALL IN ONE STRING B IN THE PROGRAM BELOW I COULD THEN EXTRACT THE IRAE INFORMATION USING VAL AND MIDS FUNCTIONS IN ORDER TO RUN THE PROGRAM CONTINUOUSLY THE L FOR NEXT LOOP WAS ALSO ADDED I ALSO TOOK THE
75. DE LD A 0D3H SUB D LD IX 00H A JR H5091 VERIFY this instruction with babyroot src H5091 18FFH vs 1800H PUSH DE PUSH AF LD DE 3COOH H5096 LD A DE CP 20 JR Z H509E INC DE JR H5096 H509E LD AVE CP 04H JR NZ H50AD LD A 20H DEC DE LD DE A DEC DE LD DE A DEC DE LD DE A DEC DE LD DE A H50AD POP AF OAH JR NC H50B6 ADD A 30H JR 50 8 H50B6 ADD A 37H H50B8 LD BE X PUSH BC LD B OFFH H50BC DJNZ H50BC POP BC TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 54 POP DE LD 0 9 SUB D LD IX 37H A JR H50C8 VERIFY this instruction with babyroot src H50C8 18FFH vs 1800H PUSH IX PUSH IX POP HL POP DE LD A D XOR 20H LD D A PUSH DE PUSH DE LD B 90H H50D6 DEC HL DEC DE DJNZ H50D6 10 BC OOFFH LDIR POP HL IX CHANGED FOR MODEL L 22H E A 20H 2 HL HL A BC 000DH HL BC A 70H EO BO 70 30 HL 16K 32K 48K 64K HL A L 11H HL rg Jg a z Z Z G tt 4 X Et gt ti r X I E OP NOP Larry Kraemer is an ex Military USAF Officer and a retired Electronics amp Instrumentation Technician that has a hobby of Amateur Radio Advanced Class NOP and Computers with Computer END Repair experience TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 55 ine program was wrieh Dy vw
76. DISKETTES SVD WHICH SIT BETWEEN A PC AND A SYSTEM 80 FOR FURTHER DETAILS ON ANY OF THE ABOVE ITEMS PLEASE CHECK OUT THE INDIVIDUAL WEBSITES THERE ARE LINKS READY TO USE ON TRS 88 eORGe UK FOR THOSE OF YOU WHO WILL RECALL IN THE LAST ISSUE THE EXCITEMENT ON THE RUN UP TO XMAS WHEN I THOUGH I MIGHT BE RUNNING REAL DISKS ON MY Mle WELL I M SORRY TO REPORT THAT SANTA GOT IT WRONG JUST A BIT THE TWIN DISK DRIVE I RECEIVED WAS FROM A SWITCHABLE 40 860 TRACK EX BBC BIT OF DID WARN ME ABOUT THAT POSSIBILITY I MANAGED TO FIND A BBC DISK CONTINUED ON PAGE 2 PAGE 1 DRIVE GUIDE ON EBAY AND THE DIAGRAM BELOW SHOWS THE PROBLEM IT SEEMS IT CAN READ AND WRITE 42 OR 88 TRACK DISK WHICH IT HAS WRITTEN ITSELF QUITE HAPPILY BUT IT S NOT ABLE TO READ OLD STYLE 42 TRACK DISKS NOT TO WORRY TOO MUCH THOUGHs I VE STILL GOT MY VIRTUAL DISKS ON MATTHEW REED S EMULATORs IT S JUST THAT I WOULD HAVE LIKED TO TRY AND READ MY OLD DISKS FROM THE 198045 IT S NO GOODs I SHALL HAVE TO SEND THEM OFF TO IRA FOR CONVERSION 48 40 TRACK TRACK O TRACK WIDTH TRACK WIDTH THE SECOND IS ON HARD DISK PARTITIONING ON THE M3 amp M4 S THE LATTER HAS STEP BY STEP INSTRUCTION TO HELP AS YOU GO ALONGe IT S A VERY IMPRESSIVE ARTICLE WITH A LOT OF TECHNICAL DETAIL AND QUITE MIND BLOWING TO ME THEN THERE S PART ONE OF LAURIE SHIELDS ASSEMBLER NOTES FROM THE 1980 S IF YOU
77. E 27 ISSUE 1 MARCH 2013 PAGE 30 Second Floppy Drive to Manual Lockout N RSFORM6 3 Prompt as follows Disk pack name HARDC Password PASSWORD Manual Lockout N RSFORM6 4 Prompt as follows Disk pack name HARDD Password PASSWORD Manual Lockout N 7 Relocate th SYSTEM DRIVE 6 DRIV Prompt as follows I O ADDRESS 2 ERS FLOPPY 8 BACKUP 0 1 NEW S I Q N 9 Identify SYSTEM SYSTEM 5 10 Generate SYSGEN DRIVE 5 EXAMPLE 2 6 using the SYSTEM command Perform a disk backup to the Hard disk to copy the files over the Hard Disk as the system disk the configuration file on the boot floppy for the hard disk Partitioning by CYLINDER 1 Power on Hard disk then the TRS 80 Model 4 2 Boot Model 4 with LS DOS 6 3 1 disk which has RSHARD6 DCT and RSFORM6 CMD on it 3 Configure the hard disk by entering the SYSTEM command SYSTEM DRIVE 1 DISABLE DRIVER RSHARD6 Prompt as follows Enter drive address 1 2 and F R 1 F gt enter Enter the STEP RATE 10us 7 5ms 10 enter Enter the physical TRACKS per surface 306 820 Enter the total number of HEADS 4 gt 6 Enter partition s number of heads 1 4 gt 6 Enter partition s number of cylinders 153 136 4 Format the Hard disk using the TRSFORM6
78. E FIRST FOUR LETTERS OF MY NAME HARD IN ASCII IS 72 65 62 66 FOR THE SAKE OF THIS DEMONSTRATION YOU MIGHT AS WELL USE THE 5 BUT YOU CAN USE ANYTHING ELSE IF YOU LIKE AFTER YOU HAVE TYPED THE LINE NUMBER AND SPACE TYPE THIS MAKES CERTAIN THAT THE PROGRAM WILL IGNORE THE LINE FOR YOU MUST PAGE 3 REMEMBER THAT IT IS THE LINE THAT WE ARE NOW ENTERING THAT WILL ACTUALLY FORM PART OF THE PROGRAM IN OTHER WORDS IF IT WERE A VALID COMMAND THE PROGRAM WOULD RECOGNISE IT AND ACT UPON IT SO WE TYPED REM AND CONTINUE WITH OR WITHOUT A SPACE TO THE ASCII REPRESENTATION MENTIONED ABOVE HIT THE ENTER KEY AND WE WILL NOW HAVE THE FOLLOWING 10 REM 72658268 THIS THEREFORE IS THE WATERMARK AND WE MUST NOW PROCEED TO COVER IT UP TYPE EDIT 18 AS YOU KNOW THE LINE NUMBER WILL APPEAR ON THE NEXT LINE FROM NOW ON YOU MUST BE A BIT CAREFUL AND BEFORE PROCEEDING IT WOULD BE WISE TO DECIDE UPON THE CONTENTS OF THE MASKING LINE I ALWAYS USED TO LOOK AT THE GENERAL CONTEXT OF THE PROGRAM TO MAKE SURE THAT THE LINE DID NOT STAND OUT TRY AND AVOID FOR INSTANCE THE OPENING OF A LOOP BECAUSE YOU WILL NOT BE CLOSING ITe ANYWAY THIS I MUST LEAVE TO YOU FOR THE PURPOSE OF THIS DISCUSSION WE WILL ASSUME THAT OUR MASK IS GOING TO BE IF X 1 THEN 500 WE LEFT THE PROCEDURE WHERE WE HAD THE LINE NUMBER AND THE MACHINE WAITING FOR ENTRY PRESS THE X KEY THIS WILL TAKE YOU TO THE END OF THE LINE PRESS THE SH
79. E STABLE DOOR AFTER THE HORSE HAS BOLTEDs BUT IN ONE COURT CASE WE USED IT SUCCESSFULLY SO IT IS WORTH WHILE AS I HAVE SAID THE OVERALL CONCEPT IS THAT A LINE IS TRSBBIT VOLUME 27 ISSUE 24 DECEMBER 2913 INSERTED IN THE PROGRAM WHICH IS OVER WRITTEN BY A NONSENSICAL LINE IS THIS LATTER WHICH APPEARS ON A VDU DISPLAY UNFORTUNATELY THE ANOMALY SHOWS UP ON A LINE PRINT BUT ONE CANNOT HAVE EVERYTHINGe THE BEST WAY OF EXPLAINING HOW TO DO THIS IS TO ACTUALLY CARRY IT OUT ON A COMPUTER IT DOES NOT MATTER WHETHER IT IS OR A DISK MACHINE NOR WHETHER IT IS MODEL I OR MODEL III IT ALSO WORKS ON THE VIDEO GENIE AND GENIE Ie I WOULD SUSPECT ALSO ON THE GENIE 11 BUT I HAVE NEVER TRIED SO SWITCH ON YOUR MACHINE AND GO INTO BASICe LOAD ANY PROGRAM THAT YOU WANT OR IF YOU PREFER SIMPLY CARRY OUT THE INSTRUCTIONS FROM THE KEYBOARD WHICH EVER COURSE YOU ADOPT WE ARE INTERESTED IN INSERTING A LINE SO FOR THE SAKE OF ARGUMENT WE WILL CALL IT LINE 18 BUT OF COURSE IT MAY BE ANY NUMBER IF YOU ARE INSERTING INTO AN EXISTING PROGRAM COURSE MAKE SURE YOU ARE NOT OVER WRITING AN EXISTING LINE NUMBER BEFORE YOU ACTUALLY START TYPING YOU MUST DECIDE ON WHAT WATERMARK YOU WANT IT IS BEST TO USE SOME SORT OF INSCRIPTION FOR OTHERWISE IF ONE GOES THROUGH MEMORY WITH A MONITOR THEN WHATEVER THE WATERMARK IS WILL QUICKLY SHOW UP WE USED TO USE THE ASCII NUMBERS REPRESENTING TH
80. EN END RETURN P zSTRING 755 32 RETURN DATA 1351 98595131751 982651 22151 9B DATA 491 92491 9632591 92591 9G 9151 92691 9G 31351 22651 9B DATA 1519133292791 9698519191293 392751 9B DATA 251913591 92691 9 9359191392 925891 989491 9139292431 9B DATA 5515115650510535175150 DATA 18051212 5191751 989185131251 91751 9B DATA 128515175150512951517515051295151751505125151751580 DATA 12851517515051295151751505129515175150512515175250 DATA 1859385992313 979856922 98 DATA 99 WE HOPE YOU LIKE THE XMAS CANDLE IT S JUST TO WISH YOU ALL A VERY MERRY CHRISTMAS AND A HAPPY NEW YEAR THE MODEL 1 WILL BE 36 YEARS YOUNG IN 2614 DUSTY amp DEE TRSSBIT VOLUME 07 ISSUE 04 DECEMBER 2013 PAGE 31 With little effort and not much money you can increase the memory of your TRS 80 Model to include RTTY and other sophisticated modes of communication in its repertoire Updating The TRS 80 Model To 48K Memory With 64K Chips BY LEW MCCOY WIICP AND FRED TREASURE KABNJY This photo shows the Chips metalli and winaq iiio fhe eire As mentioned in the text the ROMS shown bear no resemblance to fhe origina TRS 80 TRS B0 is registered trademark of Radio Shack Te reasons why the camer of TRE ROT Medel might wart memory ihe computer proper nat in tha interface With Tha re cent drop in prices on 4164 dynamic RAM about 50 for a compete sat of ir beco
81. EOD GP 1 3 8 780B 20P3 JR NZ GETCHAR 9 780D 00 NOP 10 Rest of Main Program etc Now test it as before but this time the program will carry on accepting characters from the keyboard until the Enter key is pressed We have made some progress but if you think about it not all that much firstly you will find that by repeated pressing of the back arrow key you can wipe out everything on the video and secondly even if we key in something useful our program hasn t remembered it 11 the characters were only known by the computer for a brief instant between the key being pressed and their appearing on the video To be really useful our program must Store each key depression somewhere so that they can all be handed onto the next part of the program It must also keep a count of the characters so that backspacing beyond the first one is not allowed Later on there will be further complications about such things as unprintable characters or those keys which mean special things such as Clear but all of that will wait for the next session TRS BIT VOLUME Q7 ISSUE 23 SEPTEMBER 2013 PAGE 10 LOOKING FOR FAST INEXPENSIVE UNLIMITED MASS STORAGE FOR YOUR TRS 80 MODEL VII1 4 4P 4D The amazing Emulates TRS 80 hard drive but faster than any hard drive Works with your favourite DOS LS DOS LDOS CP M N
82. ESSAGE 5 7803 CD1478 CALL VIDEOUT 6 7806 00 NOP For Breakpoint 7 7807 0C505245 MESSAGE DB 12 PRESS ENTER CR 7 7808 53532045 7 78 4E544552 7 7813 OD 8 7814 46 VIDEOUT LD B HL 9 7815 23 VID1 INC HL 10 7816 7E LD A HL 11 7817 CD1D78 CALL OUTPUT 12 781A 10F9 DJNZ VID1 I3 TOLC c9 RET TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 19 14 781D D5 OUTPUT PUSH DE 15 781E FDES5 PUSH IY 16 7820 CD3300 CALL 33H 17 7823 POP LY 18 7825 Dl POP DE 19 7826 C9 RET 20 END If we didn t want the CR at the end of the message it could easily be omitted provided we reduce the counter from 12 to 1 This particular technique is used in Scripsit to display all the various prompts and messages on the bottom line It suffers as does the earlier example in needing an extra byte be it the counter at the beginning or the special marker at the end to indicate the length of the message string To do the job really efficiently we need a technique that somehow can manage without any extra bytes The secret is in appreciating that all displayable ASCII characters have values less than 80H decimal range 32 to 127 so if we add 128 to the last character of each string then simply by testing if greater than 127 we will know whether or not the whole message has been d
83. HERE CAN BE A SLIGHT IMPERCEPTIBLE FLICKER WHICH TO THE KNOWLEDGEABLEs WILL BE A DEAD GIVE AWAY TRSBBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 4 IVAN KENNEDY S MODEL 4 by Ian Mavric contributing writer This article first appeared in the Oct 2013 edition of SYDTRUG News Back in February Ivan emailed me saying he had a number of old TRS 80 systems which he would like to get fixed and asked if I was up to the task Among the initial delivery was 6 Model 4s My briefing was simple Ivan wanted a good working Model 4 to return to Sydney with The Model 4s dropped off had clearly been in heavy usage by passionate enthusiasts at Sydtrug It was explained that some had belonged to Greg Read some from Ivan at least one was from a local airbase but something thing was clear they had all been modified to keep running and some had been ratted for parts to keep others alive Some were missing disk drives others were missing power supplies or motherboard and others we missing even more Rather than talk about each machine individually I ll talk about how I assess a machine s Suitability for repair restoration or junking First thing to do was to set up each machine take the lids off and assess what was inside and also take stock of what would potentially make a nicely restored machine Things which get noted at this point in time Case condition is it damaged or will it come up nice after cleaning has it been modified
84. IFT KEY AND THE IN OTHER WORDS WE ARE MAKING ANOTHER REM STATEMENT KEEP YOUR FINGER ON THE SHIFT BUTTON AND USING THE LEFT HAND ARROW BACK SPACE TO THE BEGINNING OF THE WATERMARK THAT IS TO SAY TO THE R IN REM NOTE THAT THE CHARACTERS HAVE NOT BEEN ERASED AS YOU BACK SPACE BUT NOW THAT YOU HAVE GOT TO THE R IT HAS DISAPPEARED RELEASE THE SHIFT KEY AND TYPE IN YOUR MASKING LINE AS YOU DO THIS THE WATERMARK LINE WILL DISAPPEARe WHEN YOU HAVE GOT TO THE LAST 508 PRESS THE ENTER KEY AND YOU ARE FINISHED TO TEST IT DO A LIST AND YOU WILL SEE THAT THE MASKING LINE IF X ETC IS LISTED THAT LINE HAS NO RELEVANCE TO THE PROGRAM WHATEVER IT WILL HAVE NO AFFECT SO FAR AS THE DISPLAY IS CONCERNED THE ONLY WAY OF FINDING THE WATERMARK IS TO EDIT THAT LINE AGAIN SO TYPE EDIT 18 AND JUST FOR FUN HIT THE L KEY FOR LIST YOU WILL SEE THAT YOU STILL HAVE THE MASKING LINE NOW HOWEVER SPACE THROUGH THE LINE WITH THE SPACE BAR AND YOU WILL SEE THE UNDERLYING WATERMARK APPEAR AND THAT IS HOW IT IS DONE A SIMPLE EASILY INSTALLED BUT NO LONGER LITTLE KNOWN GIMMICK OF THE MICROSOFT INTERPRETER ONE FINAL WORDe IF YOU INTEND TO USE THIS GIMMICK SERIOUSLY MAKE THE LINE AS SHORT AS POSSIBLE FOR IN FACT AS IT IS LISTED IT DOES DISPLAY THE WATERMARK BUT THIS IS SO QUICKLY OVER WRITTEN BY THE MASK THAT YOU DO NOT NOTICE IT IF YOU HAVE A LONG WATERMARK THEREFORE A LONG MASKING LINE T
85. ING TRAINEE ASSEMBLER PROGRAMMERS LAURIE SHIELDS HAS KINDLY UPDATED AND REVISED PART 3 OF HIS ASSEMBLER NOTES SERIES LAURIE TAKES US THROUGH THE CALL SUBROUTINE AND PLACING OUTPUT TO THE VIDEO MAV GIVES US DETAILED INSTRUCTION ON HOW TO BUILD THE TOROID MODEL 1 POWER SUPPLY AND FINALLY IN HIS USUAL EXPERTLY DETAILED MANNER TALKS US THROUGH VARIOUS PROBLEMS WITH THEIR SOLUTIONS HE ENCOUNTERED WHEN REPAIRING TRS 8 S WELL THAT S JUST ABOUT IT FOR NOWU I D JUST LIKE TO REMIND YOU ALL THAT THE NEXT EDITION WILL BE THE XMAS SO IF THERE S ANYTHING IN PARTICULAR YOU D LIKE TO SEE PLEASE EMAIL ME AND I LL TRY MY BEST TO HELP TAKE CARE gt DUSTY HERE S A PHOTO MAV EMAILED TO OF A FREHDs HOUSED IN A STANDARD 5 1 1 DISK DRIVE CASE VOLUME 27 ISSUE 93 SEPTEMBER 2913 PAGE 2 IN MAV S WORKSHOP by Ian Mavric CURING MODEL 1 RS232C SERIAL BOARD WOES PART 2 Last time I talked about the Baud Rate Generator as installed in the TRS 80 Model I RS232 board and how to replace it if it goes bad on you Today s discussion will centre around the UART Universal Asynchronous Receiver Transmitter chip and its line drivers SIMPLE TESTS SAVE TIME AND HELP NARROW DOWN THE PROBLEM Every so often I find that the RS232 is completely unresponsive to testing The way I test an RS232 is to
86. IT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 36 also leave GPIO pins 7 and 8 alone as they are part of the SPI interface and unavailable as I am using that interface for read and write data GPIO 2 and 3 have pull up resistors on the board itself so I use them as inputs Note All outputs are pulled up to 5v by 150 ohm resistors on the Expansion Interface Write Protect output connected to GPIO 18 Header pin P1 I2 Track 0 output connected to GPIO 23 Header pin 1 16 Read data output connected to GPIO 10 Header pin P1 19 Index Pulse output connected to GPIO 24 Header pin 1 18 Drive Select 0 input connected to 2 Header pin P1 03 has 1K8 pull up on the board Drive Select 1 input connected to GPIO 25 Header pin P1 22 Motor On input connected to GPIO 4 Header pin P1 07 Direction Select input connected to GPIO 17 Header pin P1 11 Direction Step input connected to GPIO 27 Header pin P1 13 Drive Select 2 input connected to GPIO 22 Header pin P1 15 Write Gate input connected to GPIO 15 Header pin 1 10 Write Data input connected to GOIP 9 Header pin P1 21 Update Sept 30 I found that using GPIO 3 as an input caused Rasbpian to hang while booting so I have changed Drive Select 1 to use GPIO 25 header pin P1 22 instead This problem doesn t exist under RISC OS so perhaps a driver needed to be disabled One of the drives connected to the cable should hav
87. If it is zero we go back for the next character having incremented HL first if it is non zero then that was the last character and the subroutine having done its job can return There are of course as one might expect equivalent complete routines available in the ROM and also for disk users in the DOS which will output complete character strings to the video with just a single call But there are problems in that the conventions for treating the end of string markers are not TRS BIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 21 consistent the ROM routine at 28A7H doesn t work under thes Newdos and as Tandy do not declar routines as being available they might change them one day and not tell anybody As the amount of coding involved in setting up one s own general purpose output using the o Fficial supported 33H is quite minimal then I would always way your programs will need little 99 TRS 80 comes out and should you altogether then the minimum They said it couldnt be done Galactic FIREBIRD Those ever circling swooping diving Firebirds of the famous arcade machines brought to the micro in Mike Chalk s ultimate achievement Galactic Firebird Yes it s the latest in the Kansas Arcade series but alas his last for Mike has been writi
88. LAY PROCESSES TRIGe FUNCTIONS AND OPERATES IN OCTAL gt BINARY HEX AND DECIMAL THEY WERE ALSO SELLING 8 PACKS OF 2 FINGER PLAIN CHOCOLATE KITKATS TOO WHICH NEEDLESS SAY I COULDN T RESIST AS YOU CAN SEE FROM THE SMALL 7 LINE PROGRAM BELOW IT WAS SOON UP AND RUNNING THE SCREEN HAPPILY REFRESHED JUST ABOUT AS QUICK AS I COULD TYPE AND THE BOYS SEEMED TO ENJOY THEMSELVES Le 2 CH DATA 9449 192604292 15261 296 1823 eeta ca 38 F RZ BTD Z READA UZ As NEAT 48 ASSINKE VS IFA THENSHELSEPR INTaee A JH DEFUSRE YARPTR AUCH bB rA GOTOH AFTER ALL THE EXCITEMENT HAD DIED DOWN I GOT TO THINKING WOULD THIS TURN INTO A GOOD OLD ONE LINER AND YES AS YOU CAN SEE BELOW WITH A COUPLE OF MINOR CHANGES REPLACING LINE 42 WITH A LOOP INSTEAD OF A 06070 IT DID THEN I STARTED TO GET A BIT TOO CLEVERs AS MENTIONED EARLIER I THOUGHT ABOUT USING A ROM CALL WITHIN THE ASSEMBLER PROGRAM TO REPLACE THE INKEYS ROUTINE NEEDLESS TO SAY GOT INTO BIT OF A MESS BUT THANKS TO PETER STONE I WAS PUT ON THE RIGHT TRACK AGAIN AS USUAL I D GOT A PUSH AND POP IN THE WRONG PLACE THEN I REALISED I D NEED TO GET AN EXIT ROUTINE INTO THE PROGRAM AS THE BREAK KEY WAS LOCKED OUT AND A SYSTEM REBOOT WAS THE ONLY WAY TO QUIT THE PROGRAM NOT GOOD PROGRAMMING PRACTICE EH AT THIS POINT THE DATA STATEMENTS SEEMED TO BE GROWING EXPONENTIALLY SO I DECIDED TO QUIT WHILE
89. LD PERSONAL M1 DISKS WHICH HAVE BEEN STORED AWAY FOR OVER 38 YEARS TOGETHER WITH A FEW OTHERS DONATED TO THE SITE TO IRA FOR CONVERSION AND THENs TAKE ADVANTAGE OF THEM VIA MATTHEW REED S EMULATOR THERE WAS ONE SPECIFIC PROGRAM THAT I REALLY DID WANT TO HAVE AVAILABLE AGAINs CWHICH FEATURES AS AN ARTICLE ON PAGE 2972 SO I DULY PACKED THEM UP AND POPPED DOWN TO THE POST OFFICE WHAT A SHOCK POSTAGE WOULD BE OVER 129 NO GUARANTEED DELIVERY BUT SHOULD ARRIVE WITHIN 28 DAYS IF ALL GOES WELL NO TRACKING AND NO INSURANCE CHOW MAY I HELP YOU SIR EH WELL BACK TO THE DRAWING BOARD OR RATHER GOOGLE WHERE I CAME ACROSS THE PARCEL2GO COM WEBSITE THE PACKAGE COULD BE COLLECTED FROM MY HOME gt DELIVERY SHOULD TAKE 3 WORKING DAYS FULLY TRACKED AND INSURED FOR FREE UP TO A VALUE OF 285 THE COST JUST IN CASE YOU WONDERED WAS JUST UNDER 34 50 I DULY PAID USING A CARD AND ON THE AGREED DATE FRIDAY THE MAN AND VAN ARRIVED PICKED UP THE PACKAGE AND OFF HE WENT INTO THE SUNSET SO TO SPEAK NOW HERE S THE REMARKABLE MONDAY EVENING TIME s I HAD AN EMAIL FROM IRA TO SAY THAT THE PACKAGE HAD ARRIVED AND TUESDAY EVENING UK TIME I WAS BROWSING AN EMAIL FROM IRA CONTAINING A ZIPPED FILE OF MY 78 ODD 5 4 DISKS TRSBBIT VOLUME 7 ISSUE 2 JUNE 2013 WHAT BRILLIANT SERVICE ALL ROUND EH ONCE AGAIN THANKS IRA FOR SUCH DEDICATED SERVICE WHICH WAS TRULY WELL ABOVE AND BEY
90. LD HL A Put in Buffer 41 7835 23 INC HL Bump the pointer 42 7836 04 INC B Add 1 to the counter 43 7837 CD7178 CALL OUTPUT Put it on the video 44 783A 18D1 JR KEYIN Go for next one 45 783 00 TEXTEND NOP For Breakpoint 46 783D 454E5445 MESS1 DS ENTER NAME 30 14 0 46 7841 52204E41 TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 19 46 7845 4D45203A 46 7849 1EOEO00 47 BUFFER DS 25 48 49 7865 7E VIDEOUT LD A HL we had before 50 7866 23 INC HL 51 7867 B7 OR A 52 7868 CS RET Z 53 7869 CD7178 CALL OUTPUT 54 786C FEOD CP CR 55 786E 20F5 JR NZ VIDEOUT 56 7870 C9 RET 57 7871 D5 OUTPUT PUSH DE 58 7872 FDE5 PUSH IY 59 7874 CD3300 CALL 33H 60 7877 FDE1 POP IY 61 7879 D1 POP DE 62 787A C9 RET 63 7878 D5 KEYSCAN PUSH DE 64 787C FDE5 PUSH IY 65 787E CD2B00 CALL 2BH 66 7881 FDE1 POP IY 67 7883 D1 POP DE 68 7884 C9 RET 69 END The first point to watch with this program is for disc users in particular but it applies in a general way to all With the source file growing larger the end is others getting very close to 7800H amp End funny things will happen when we assemble use Q to ask Zen for the Start and should the end of the file go beyond 7800H some As the object code is generated the Load command will place it in memory from 7800H onwards obliterating the letter part of the source file and whilst being perfectly understandable it is damn
91. M 1 Enter WHAT HAPPENED TO MY FLOPPY DRIVES As you built your hard drive partitions and they started to take over volume drive numbers 0 1 2 and 3 the floppy drives were disabled as the numbers were given to hard drive volumes This is normal After you have set up all your hard drive partitions you need to bring your floppy drives back online with new numbers and this is done using the command SYSTEM DRIVE x DRIVER MOD3 or SYSTEM DRIVE x DRIVER FLOPPY The former being for Model III LDOS and the latter being for Model 4 LS DOS COMPLETING THE SETUP Those familiar with LDOS LS DOS will be familiar with the SYSGEN command it saves your current configuration in a CONFIG SYS file so that next time you boot that floppy the previous configuration is restored This is even more important for hard drives because as well as saving the hard and floppy drive configuration it also transfers control of drive zero to the hard drive partition 1 upon boot In Model III LDOS the command is SYSTEM SYSGEN DRIVE x lt Enter gt where x is the floppy drive you normally boot from drive 0 on a floppy system and probably drive 4 or 6 on a hard disk system The equivalent command on Model 4 LS DOS is SYSGEN DRIVE x lt Enter gt UAL BOOT BOTH LDOS AND LS DOS ON A SINGLE HARD DRIVE As you play around with setting up a hard drive it soon becomes apparent that you can enable and disable hard drive partitions in any ord
92. Model 4 Looking at feedback from TRS 80 Model III and 4 users they compiled a wish list of specifications for the new machine and reading through them they look strangely familiar Increased memory past 128K preferably 256K or more A 16 bit of around 6 8MHz Hi Resolution graphics as standard Colour and sound better than the Apple IIe and IBM PC XT Vastly increased disk storage capacity Internal hard disk drive More function keys Backwards compatibility with the Model III 4 Reading this list except for the last item reads like the Specs list for the Tandy 2000 With projects like August on the drawing board no wonder future development of 7800 which Zilog was lazy to release anyway based advanced TRS 80s was shelved Examined in this context the Tandy 2000 really does appear to be the zenith of TRS 80 development and although a failure in the marketplace it s a success from a performance and reliability aspect as well as setting very high final standards for ergonomics and user eye neck and hand fatigue these becoming big issues in the mid 1980s So next time you see a sad looking Tandy 2000 languishing on eBay CraigsList or a thrift store give thought to what was at the time one of the most powerful and expensive TRS 80s one of the last real signs that Radio Shack was trying to be a force to be reckoned with producing innovative new products Instead of just languishing in the small but comfortable mo
93. NCrement to HL and subtract DECrement from BC Since the Flag registers generally go on strike when we are doing 16 bit arithmetic the Z flag will not be triggered when BC becomes zero so the only way to find out if the whole of the 1024 in BC has gone is to check B and C separately and if either of them are not zero then carry on looping 7 Load the clever A reqister with the value held by B 8 ComPare means for the Z280 test for the difference between the A register and in this case 0 If in testing the Z80 finds no difference then the Z flaq will be set 9 Is it because if not there s work still to be done 10 Check the value in C the same way 11 Compare 12 Keep up the good work 13 Everybody happyv Fifth simple rule Condition testing causes most of the headaches in assembler At the end of our program we would have filled the video completely and the 2780 world then execute the next machine code instruction which if we do nothing about it would be just whatever the next byte in Ram just happened to be The fact that we have put an END in our code does not mean that the computer will respond with gt READY the way it would in Basic when control is passed back to the keyboard In machine code the only way to stop the 780 chip is to switch the computer off this being rather a drastic measure We can however hand control back to Zen provided we arrange it before we go blasting the video w
94. O To turn these Mnemonics into actual machine code bytes we activate the assembler in Zen by keying A lt E gt Disc users will be prompted by Zen for Source File gt to which the answer is simply lt E gt unless they want to assemble direct from disc and then they wouldn t be reading this chapter Then Zen asks OPTION Since you might want to just check for errors or display the assembled code on the video or write it to cassette asa System tape etc this is the stage at which you tell Zen where to send the output Since we want it on the Video key V lt E gt and you will get the complete program assembled as shown below except for the headings or an error message such as OPERAND or HUH where Zen can t decipher your typos TRSSBIT VOLUME 27 ISSUE 2 JUNE 29013 PAGE 19 Line Memory Object Label Opcode Operand Address Code I ORG 7800H 2 7800 21003 LD HL 15360 3 7803 010004 LD BC 1024 4 7806 36A1 LOOP LD HL 161 5 7808 23 INC HL 6 7809 OB DEC BC 7 780A 78 LD A B 8 780B 00 CP 0 9 7800 C20678 JP NZ LOOP 10 7810 79 LD A C 11 7811 FEOO CP 0 12 7813 C20678 JP NZ LOOP 13 END Note that Zen has understood the decimal numbers but in generating the machine code program these have all been changed into hexadecimal Now somebody at the back is bound to ask whether it really takes as much effort to find out if something has been done lines 7 12 as it does to do it lines 2 6 In all
95. OKES above the 16K boundary Lets examine the numbers in that region firstly the last byte in 16K and then the next one and finally the last byte in 48K These sizes of course refer to RAM we must add another 16K to them for the ROM keyboard video etc Top of 16K 7FFFHex 0 1 11111111111111 Next Byte 8000Hex 10000000000000 0 0 Top of 48K 1111111111111111 If the 780 has been told to interpret these as human numbers then the second two are obviously negative Setting these numbers out with the values of each bit we get BITS Sign 14 1 32 T2 11 10 9 8 7 6 5 4321 0 32768 16384 8192 4096 2048 1024 512 256 128 64 32 16 8421 7FFF 0 1 1 EN 1 1 1 1 1 1 1 11111 Positive 32767 8000 1 0 0 0 0 0 0 0 0 0 0 00000 Negative 32768 0 32768 FFFF 1 1 1 1 1 XR 1 1 1 1 11111 Negative 32678 32767 1 Don t worry if it doesn t all sink in first time but when it eventually does penetrate the grey matter you will have a sound grasp of how BASIC handles its Integers known in the trade as Signed 16 Bit Integers and you will also appreciate why in Basic the range of values that an integer can hold is limited to 32768 to 32767 FOR ADVANCED BASIC PROGRAMMERS ONLY 10 DEFINT A Z 20 X T 4 256 8 30 V VARPTR Y 40 PRINT PEEK V PEEK V 1 50 INPUT NEW VALUE Y 60 GOTO 30 70 END 58 VOLUME 27 ISSUE 01 MARCH 2013 PAGE 21 Explanation
96. OME WITH THEM BUY THIS ONE IT POWERS YOUR MODEL I SYSTEM TAKES ONLY 1 POWER POINT LIVES IN THE EXPANSION INTERFACE AND POWERS BOTH THE KEYBOARD AND Eele ONLY A145 00 SHIPPING AVAILABLE FROM HTTP IANMAV CUSTOMERe NETSPACE NET AU TRSS8 TRS BIT VOLUME 27 ISSUE 02 JUNE 2013 PAGE 4 ASSEMBLER NOTES Part 2 Laurie Shields Chapter 4 Assembler Programming Like all good stories we must have a beginning an end and something in the middle It s the middle part that s rather awkward so let s dispose of the easy bits first First Simple Rule All assembly language programs must finish with the simple statement END This tells the assembler more about him later that it has come to the end and nothing else is of any consequence and can be ignored Without an END to your program you will get an error message EOF Of course if you are using the dreaded E m you will know that just as it was being put on the shelf for sale somebody spotted there was a bit missing and it had to be added on after the END so the END wasn t the end after all and it set the scene for all the other incomplete bits of software from 2 0 to the M 3 Dos Second Simple Rule All assembly language programs need a beginning which tells the assembler he s here again the position location or address in memory for which the machine code program is written This beginning or origin statement takes the form ORG value
97. OND NORMAL EXPECTATION SO THE MORAL OF THIS LITTLE TALE 15 IF YOU VE A STASH OF OLD 5 4 DISK WITH NOTHING TO READ THEM ON OR WHICH YOU WOULD LIKE TO USE WITH AN EMULATORs SEND THEM OFF TO IRA FOR CONVERSION BEFORE IT S TOO LATE AND THEY BECOME UNREADABLE I HOPE YOU VE NOTICED I VE RECENTLY PLACED A CLUSTRMAP ON THE WEBSITE I NOTICED THE FIRST ONE ON MIGUEL S SITE AND THOUGH IT WAS A BRILLIANT IDEA I THOUGHT IT WOULD BE INTERESTING TO KNOW WHAT IF ANY WORLD WIDE INTEREST THERE IS IN THE SITE IT TOOK ME TOTALLY BY SURPRISE I THINK JUST ABOUT EVERY CONTINENT IS REPRESENTEDe A BIG WARM WELCOME TO YOU ALL I M SO DELIGHTED THAT THE OLD TANDYS STILL ATTRACT SO MUCH INTEREST SOs DOWN TO THIS ISSUE THERE S A QUICK NOTE ABOUT THE NATIONAL MUSEUM OF COMPUTING WHICH I M HOPING TO VISIT SHORTLY LAURIE SHIELD S ASSEMBLER NOTES MOVES ON TO PART TWO MAV COMPLETES HIS TRILOGY ON THE TRS 80 HARD DRIVES THERE S A SERIAL DRIVER FOR ALL US 4K OR 16K USERS WONDERS IF THE MODEL 2999 WAS THE BEST TRS 80 EVER AND FINALLY WOULD YOUR BELIEVE IT TAKE CARE EVERYONE DUSTY PAGE 2 HI DUSTY gt I THOUGHT YOU MIGHT BE INTERESTED TO HEAR ABOUT THE NATIONAL MUSEUM OF COMPUTING WHICH IS IN THE SAME GROUNDS AS BLETCHLEY PARK I WAS LUCKY ENOUGH TO GO ON A GUIDED TOUR OF BOTH BLETCHLEY PARK AND THE MUSEUM QUITE RECENTLY AND FOUND THE COMPUTER DISPLAYS IN THE MUSEUM MOST FASCINATING
98. OSS VARIOUS HARDWARE ADD ONS WHICH INCREASED MEMORY USING 116 CHIPS OVER THE YEARS BUT I D NEVER SEEN ANY INFORMATION REGARDING THE USE 1160 CHIPSU I LL TRY AND OBTAIN DETAILS FOR THE DECEMBER EDITION TRS BIT VOLUME 07 ISSUE 03 SEPTEMBER 2013 PAGE 1 AND I MANAGED TO VISIT BOTH BLETCHLEY PARK AND THE NATIONAL MUSEUM OF COMPUTING DURING JULYU BP AS YOU LL PROBABLY GUESS WAS FASCINATING AND WE THOROUGHLY ENJOYED THE GUIDED TOURU THE NMC WAS JUST UP OUR STREET 700 EVEN THOUGH THERE WAS VERY LITTLE INFORMATION ABOUT TRS 8 SU THEY HAVE A VAST LIBRARY OF REFERENCE MATERIAL BOTH BOOKS AND UK MAGAZINES WHICH IS AVAILABLE FOR MEMBERS TO USE FREE OF CHARGEL I ONLY WISHED WE LIVED A LITTLE NEARER I M PLEASED TO REPORT THAT ONCE AGAIN THERE HAS BEEN OVER 129 DOWNLOADS OF THE LAST EDITION OF THE NEWSLETTERU THANK YOU ALL FOR YOUR CONTINUED SUPPORT 50 DOWN TO THIS ISSUE MAV CONCLUDES HIS SERIES OF ARTICLES ON THE PROBLEMS WHICH CAN BE ENCOUNTERED WITH THE 1 RS 3eC INTERFACEL THIS ARTICLE WAS MISSED OUT FROM THE LAST ISSUEU THIS WAS ENTIRELY MY FAULT FOR WHICH I OFFER MY APOLOGIES AND HOPE IT TRS BIT HASN T SPOILT YOUR ENJOYMENT OF THE SERIES TOO MUCH JUST FOR ALL OF US STRUGGL
99. POWERS YOUR MODEL I SYSTEM TAKES ONLY 1 POWER POINT LIVES IN THE EXPANSION INTERFACE AND POWERS BOTH THE KEYBOARD AND ONLY 1 5 SHIPPING AVAILABLE FROM HTTP IANMAVICUSTOMER INETSPACEL NETLIAU TRS amp O TRS BIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 6 ASSEMBLER NOTES Part 3 Laurie Shields Chapter 6 Using the ROM Routines So far we ve learnt how to load registers and memory count jump and perform certain logical operations like ADD and XOR SEC Now for the machine language equivalent of Basic s GOSUB In machine code these are still called subroutines but instead of accessing them with a GOSUB we use a CALL instruction As with the jump commands we must provide a reference to the memory address either absolutely in hexadecimal or by means of a label such as CALL SUBRI or CALL OUTPUT Just like in Basic when the subroutine has done its job it needs to instruct the Z80 to return to the command immediately following the call and this is achieved with a RET instruction Now the Level 2 ROM is jam packed with hundreds if not thousands of subroutines most of which are inextricably interlinked and which form the Basic Interpreter Some of these routines however are available for general use and the first ones we shall meet are to do with data input from the keyboard and data output to the video and printer The
100. Prepare your magnetic bulk storage device for recording and make sure the cassette floppy tape or disc has some space on it and key W E Zen will then ask you for a name or filespec as appropriate and then record your source file Cassette and floppy tape users have the V command to verify that the recording is a good one and does not generate any checksum errors Sixth simple rule Assembler is so fast that five minutes of programming will take at least five hours to get right This is known as the advantage in speed of Assembler over Basic TRS BIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 12 your third and greatest wish The new Genie III surpasses even its predecessors by harnessing all the benefits of modern professional microcomputing in one unit Software availability is exceptionally good in factthe Genie III has more software available than any of its competitors And even if you don t want to use a ready made business package with the Genie III you can write your own The Genie III is fully operational in either CP M or level II basic It has a built in screen 64K RAM and dual disk drive with 730K storage capacity all incorporated in its compact and attractive casing The new Genie III is an obedient slave in the office quickly and quietly taking care ofall yourroutine work from printed invoices mailing lists and letters to stock control Itall costs less than a new office junior yet it s simple en
101. RD ACTS JUST AS AN ORIGINAL HARD DISK THE 4 GUYS WHO DESERVE AN HONOURABLE MENTION FOR DEVELOPING THIS FANTASTIC BIT OF KIT ARE FRED VECOVENs ANDREW QUINNs DAVID COOPER AND IAN MAVRIC FULL INFORMATION AND ORDERING DETAILS OF BOTH THESE BITS OF KIT ARE ON MAV S WEB SITE MATTHEW REED HAS RELEASED VARIOUS UPGRADES HIS Z80 ASSEMBLER IS NOW ON 1 2 TRSTOOLS IS AT V14 09 AND TRSREAD WRITE IS NOW AT 4 33 TWO NEW EMULATORS HAVE APPEARED ONE FOR THE PC BY JIM EADIE AND ONE FOR THE ANDROID OPERATING SYSTEM BY ARNO PUDER I NOTICED THE OTHER DAY THAT THE CLUB190 ARE OFFERING A CONVERSION SERVICE FOR ANYONE WHO CAN NO LONGER READ THEIR TPDD AND TPDD2 DISKS AND WOULD LIKE TO USE THEM ON THEIR NADSBOX CHECK OUT THE CLUBIS WEBSITE FOR FURTHER DETAILS THE UK S EBAY HAS SEEN A BIT MORE LIFE DURING THE LAST 3 MONTHS A MODEL 3 WITH TWIN DISK FETCHED 63 AND A MODEL 1 WITH AN EXPANSION INTERFACE NO DISKS OR MONITOR FETCHED 73 THERE HAS BEEN A COUPLE OF MODEL 1080 S FETCHING AROUND THE 59 MARK AND A MODEL 192 WHICH ONLY MADE JUST OVER 40 JOHN PYE HAS HAD A MODEL 1 ADVERTISED ON THE WEBSITE FOR NEARLY A MONTH AND SO FAR THERE S BEEN NO INTEREST SHOWN PAGE 1 FOLLOWING ON FROM THE MARCH EDITION AND THE SAGA OF MY SOMEWHAT UNIMPRESSIVE TO UPGRADE MY MODEL 1 SYSTEM TO DISKS I M PLEASED TO REPORT THAT MY NEXT COURSE OF ACTION CHEERED ME UP NO END I DECIDED TO SEND ALL MY O
102. S me R 22092359 A 2 SREI RMAZBLLZ 2555325 uz Stee ee gez EEZESSZ z1348ST7B8YS san ZENIZEME E ZZELZEAM 55555 J eer ere eee ee ee t t wx AzREZHEMI ETZSEZZZ WWHiDa237 QZuxusuws amp 82232223 GEI 543820348 SxRRUASS SABER SS ZEMHNETZEZEEAMNLE 39272uux m amp lt SRS far X 10480 TO IOS NET 1 PME 526 0 POCE 10527 80 PEINT SRO BATA 33 0 00 17 1 80 1 290 3 94 32 229 LPB 201 92 100 DATA 30714 24 1 29m 10 90 94 6 221 29 6 BATA 33 0 56 175 005 09 048 102 119 94 126 834 LiG do V6 209 201 09 029 LAB 40 41 I 061 119 43 4 3 109 71 10 184 CATA 5 2 2 213 06 07 h Bb 109 18 00 5 22 18 113 16 43 SELIR L8 TL 0 206 16 14 0 24 199 29 CATA 100 14 190 10 15 19 15 19472 1 M 124 200 18 27 07 25 120 130 244 15 16 15 i h h 10 124 200 TATA BS IEA AA I PODAR 011 180 212 119 12224 298 21 08 CATA 1270 0 06 PAd 39 40 2 19 24 2 12 204 4 22 14 TATA 40 3 0 18 0 1807 0 27 10 241 294 10 48 4 108 DATA AESMA A 190 58 18 17 6 268 DA 284 080 208 02 M 186 ni 119 68 h ah a bn dom 100 050 2 07 13 15 27 14 nia 237 174 001 2 62 02 921
103. Serial number and Catalogue number low serial numbers are generally more desirable and the catalo number helps determine what the original configuration of the Model 4 was 26 1067 is a 16K diskless machine while a 26 1069 is a 64K dual drive Model 4 Does the CRT have screen burn it makes sense to use a CRT without annoying images burnt into it Which version video board is installed the later digital board gives a clearer image than the early analogue board What is the keyboard like yellowed missing keys missing its RAM size badge Next thing I do is put power to a system which looks the most complete most cases with Ivan s computers the mains filter capacitors had blown so at this point I removed a power supply which looked pretty good and replaced its filter caps C1 C2 and C12 and found myself greeted with a happy Cass prompt from one of the motherboards I earmarked this system to be one to fix for Ivan to return to Sydney with Once at this point its easy to test the CRTs just be plugging them in and seeing what sort of image you get Three showed a TRSBBIT VOLUME 27 ISSUE 4 DECEMBER 2013 PAGE 5 decent image two had green CRTs one had a B amp W CRT two showed nothing at all no signs of life and one had arcs and sparks going on what I call signs of life just the wrong ones A nice case with a clear green CRT was chosen for Ivan At this point one can plug in all the keyboards one
104. Sq o1i1 lunoo 10 SUA3OO O YM ebpuieo Aue uoq qu SAUA peiunour eseqiu enp V uo ppe g Se 1 Hurjuy pue 3SVHIND eseg y T Jo sistsuoo Wad sn M N xexu OPAL aejeuirerp pue ut 1 dn STOOdS Odd vd sixoddns joods SN xexu xSdOGdhRLLDHVO NOSSDPI ODIgV4 moqe ysni suoddns puyep On ILN S eszoArugm PAGE 9 MARCH 2913 VOLUME 7 ISSUE 91 TRS BIT MAC INKER We generate lot of paper output here With all the editing rewriting listing and word processing that we do printer ribbons quickly become a major expense For a Radio Shack Line Printer VI the ribbon costs 11 95 plus tax And we seemed to Use one up every time we just ees out a 10 000 name mailing ist No longer are ribbons a major expense The Mac Inker has truly done what the manufacturer promised It has practicaly eliminated the cost of replacing ribbons We can re ink a ribbon for about a nickel and it works as good as new One ribbon has been re inked at least a dozen times now and it is still holding up In a few cases the re inked ribbor has given better print than when it was new The Mac Inker is a
105. T ON M1 RS232 CARDS AND TRS BIT VOLUME 27 ISSUE 1 MARCH 2013 PAGE 2 Large numeral generator from a program by E G Kemplen This routine displays a large numeral as a 6 by 7 matrix of asterisks Written for PET it should run on other micros quite easily The routine sets up two arrays A and A in lines 110 to 190 A contains numeral while A contains ten sets of codes used to select the appropriate element for each row This subroutine will work as it is because line 200 contains an instruction to input the value X to be displayed the four elements used to construct the PRINT J DIMACTE AS 49 BSCS SC1 42 DATA Xe DATA ty DATA x DRTR y F RIZ1TO4 RERDR CI DATA1 4 4 4 4 4 1 3 3 3 3 3 2 2 1 2 3 1 1 1 07 READACI INPUT g X PRIHT 3 F RI 1TO PRINT IBBBEBI ASCACK P I OD NEXT GOTO 2868 REM WHILE I WAS DELVING INTO AN OLD EDITION OF PERSONAL COMPUTER WORLD DURING ALL THE CHRISTMAS FESTIVITIES THIS LITTLE PROGRAM CAUGHT MY EYE I THOUGH IT MIGHT BE OF INTEREST FOR ME WHEN I M PLAYING ABOUT WITH LABEL PRINTING MIND YOU I M ALWAYS VERY WARY OF THE USUAL CAVEAT STATING SOMETHING LIKE SHOULD CONVERT QUITE EASILY FOR USE ON OTHER MACHINES AS THE PROGRAM WAS ORIGINALLY WRITTEN FOR THE COMMODORE PET I WAS QUITE HAPPY TO HAVE A PLAY AND SEE HOW I MANAGED TO GET ON I VE A LITTLE PROGRAM CONVERSION BOOK WHICH I VE HA
106. TRSSBIT HI EVERYONE AND WELCOME TO THIS BUMPER 32 PAGE EDITION WHICH STARTS OFF OUR 7TH YEAR I DON T LIKE STARTING OFF WITH SAD NEWS BUT I M SORRY TO REPORT THE UNTIMELY DEATH OF LANCE WOLSTRUPe HE S KNOWN TO MANY TANDY FANS IN THE UK AS THE EDITOR IN CHIEF OF THE TRSTIMES MAGAZINE WHICH WAS PUBLISHED IN THE STATES FROM THE LATE 1988 S TO 1995 HE WAS A BIG SUPPORTER OF ALL THINGS TANDY AND WILL BE SADLY MISSED I FEEL THERE S A BIG HOLE LEFT IN THE TANDY SCENE WHICH WILL BE VERY DIFFICULT IF NOT IMPOSSIBLE TO FILL THERE S QUITE A BIT TO REPORT ON THE NEWS FRONT ALTHOUGH EBAY UK HAS BEEN QUIET APART FROM THE SAME OLD ADVERTS FOR CASSETTE SOFTWARE AT 99 A TIME ETC I NOTICED A MODEL 199 0 S8BIT LARGE NUMERAL c RR f In this issue of E MODE 85232 MACINKER TRS BIT VOLUME 27 ISSUE 1 MARCH 2913 SELLING FOR JUST UNDER 59 MATTHEW REED HAS ISSUED VARIOUS UPGRADES TO HIS TRSREAD WRITE SOFTWARE AND TRSTOOLS MIGUEL DUTRA HAS RELEASED 1 6 OF HIS VDK 808 SOFTWARE THE MODEL1 CLUB IS RUNNING A PROGRAMMING COMPETITION ENTRIES MUST BE IN BY 15MARI3 SO BY THE TIME YOU READ THIS YOU LL BE NEEDING TO GET YOUR SKATES ON NEIL PINNER HAS A TANDY LPVIII PRINTER FOR SALE EMAIL ME IF YOU WANT FURTHER DETAILS DROID TRS SHOULD BE AVAILABLE ON BETA TESTING SHORTLY TERRY STEWART HAS A GREAT ARTICLE ON HIS WEBSITE RE SEMI VIRTUAL
107. UNLEASH THE ENORMOUS ADVANTAGE OF MACHINE LANGUAGE PROGRAMMING ON YOUR TANDY TRS 80 OR VIDEO GENIE WITH THE HELP OF KANSAS The Kansas Editor Assembler amp Debugger is the program to get you into machine language programming for not only does it include a full feature editor assembler but a complete debugger as well two in one in fact Altogether it contains 22 different commands which are available at all times and simply entered as Input In addition to the commands you have the option of outputting to either the video cassette or a printer Edit commands include Enter which allows the continuous entry of text anywhere in the file Zap to erase lines New to replace a line with a new one with line numbers automatically displayed as a guide The assembler accepts source statements in the 280 language each line divided into fields including comments which are of course ignored These include the label operator and operands which are all very extensive Symbols can be used instead of values or by using the pseudo operand your own value can be asigned to a symbol There are many commands for this all giving a very easy usage of this assembler whether source or object The commands for the assembler include Size Sort Assemble Kill Top Bottom Up Down Print Find Error messages are generated if an error is found by the assembler with the line displayed and command loop re entered The assembled program can be listed on the vi
108. UT LOOKING AT THE KEYBOARD AND BY WAY OF CONFIRMATION THAT IT WAS THE CORRECT KEY THE SCREEN WOULD BE FILLED WITH 1924 OF THEM NOTHING TOO MAJOR I M SURE YOU LL AGREE THE ONLY PROBLEM I COULD THINK OF WAS THAT BASIC WOULD BE JUST A BIT TOO SLOW AT FILLING THE SCREENe 50 THERE WOULD BE ONLY ONE THING FOR 17 IT WOULD REQUIRE A FEW LINES OF ASSEMBLER TO SPEED THINGS UP A AS ALWAYS ZEN CAME TO THE RESCUE AND WITH THE LDIR COMMAND THIS WAS ACHIEVED EASILY TOO EASILY AS IT TURNED OUT SEE THE NEXT PAGE Page 1 1 ORG 7F00H 2 LOAD 7F00H prog placed in memory here 3 7F00 21003C LD HL 15360 start of screen 4 7F03 11013C LD DE 15361 start 1 5 7F06 01 03 LD BC 1023 no of times to loop round 6 7F09 EDBO LDIR fill screen 7 7FOB C9 RET back to BASIC 8 END THE LITTLE PROGRAM ABOVE CONFIRMS THAT I THINK THIS WAS MY FIRST EVER ASSEMBLY PROGRAM THAT ASSEMBLE FIRST TIME ERROR FREE ALL THAT WAS LEFT TO DO WAS CALCULATE THE DECIMAL VALUES FROM THE 3RD COLUMN VIZ 21 92 ETC WHICH HAD BEEN PLACED IN MEMORY AT 7FO H BY ZEN I WOULD THEN PLACE THEM IN MY BASIC PROGRAM AS DATA STATEMENTS AND LOAD THEM INTO AN ARRAY FOR THIS I M TOTALLY AMAZED TO REPORT THAT I USED A MULTI FUNCTION CALCULATOR FROM POUNDLAND YEHs BELIEVE TRS BIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 24 OR THIS KIT FOR 1 HAS 18 DIGIT DISP
109. a blaze of glory Time to look for a replacement MFM drive Calls to contacts in the computer game yielded zero success and I wasn t prepared to chance my luck on a it worked when it was removed hard drive from eBay Not long after the old Toshiba went to god the FreHD appeared on the scene The FreHD is a basically a solid state drive with a battery backup RTC for the TRS 80 and System 80 PMC Video Genie computers that uses a common garden variety SD card for storage Designed by Fred Vercoven built and sold by Ian Mavric with input from many including Andrew Quinn David Cooper Malcolm McLeod Raymond Whitehurst and a cast of thousands Apologies to anyone I forgot to mention but if you have contributed to this project then take a bow A solid state drive for the old 4P this could be the way to go I swapped a few emails with Ian Mavric exchanged the necessary down under dollars and a few days later the postie arrived with a present Installation was as easy as Unplug the smouldering remains of the old hard drive and using the existing 50 pin cable plug the FreHD into the expansion slot on the rear of the 4P and connect it to a suitable 5 volt supply ATM I m using a variable bench supply but any common REGULATED 5 volt wall wart should do the job Ian supplied a CD ROM with various utilities a 40trk LS DOS 6 3 1 boot floppy and a 128meg SD card with the appropriate hard drive image Other operating systems and boot disks
110. aid such is life Getting back to the aforementioned utilities VHDUTL CMD allows for reading of the root directory of the SD card setting and reading the built in RTC displaying the firmware version as well as creating and mounting various hard drive image files IMPORT2 CMD and EXPORT2 CMD are used to transfer individual files to and from the TRS 80 and SD card These utilities TRSB BIT VOLUME 07 ISSUE 24 DECEMBER 29013 PAGE 46 make the job of transferring files between the TRS 80 and a extremely easy FUPDATE CMD is used to update the FreHD s firmware A quick search of the net will show that nearly all the software for the TRS 80 is now available for downloading from various websites The problem has been how to get this software transferred to disks that will run on the 80 Using a combination of Matthew Reed s TRS32 emulator Trstools Newdos 80 and Super Utility I have been able to make images of DSK files including self booting disks based on Percom s MicroDOS and transferring these image files to and from the TRS80 System 80 and PC via the RS232 Slow and cumbersome but it worked and worked well MULTIDOS being the only exception and that is possibly due to conflicts with the XLR8er card in my 4P The job of transferring these DSK images has now been made extremely simple thanks to a programme supplied with the FreHD DSK DCT Copy the required DSK image files from the PC to the SD card and
111. ams on the 1771 data sheet are for 2 MHz so you have to adjust them for the slower speed of the Model I Interface Signals For this discussion I will refer to output signals as Signals output from the Raspberry Pi emulator that input to the TRS 80 expansion interface and input signals as signals coming into the Raspberry Pi emulator from the expansion interface Because several floppy drives could be connected to the same line the TRS 80 used open collector TTL interfacing with 150 ohm pull up resistors to 5 volts This meant that active signals pulled the voltage down to zero TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 34 Note The connectors on the TRS 80 Expansion Interface flat two sided card edge connectors but the schematic in the technical reference manual refers to Pin numbers so Cable pin refers to the pin numbers from the schematic The output signals are Index Pulse Cable Pin 8 This short 4 millisecond pulse is sent at the beginning of every track On a real floppy drive this is generated by a photocell pointed at a LED shining through the index hole on the floppy disk Track Zero Cable pin 26 Active when the R W head is at track zero the home position This is used by the floppy disk controller when seeking Write Protect Cable pin 28 Also generated by a photocell LED combination when the write protect notch on the disk is covered Read Data Cable pin 30 This is the data fro
112. an beyond about 1984 You have to hand it to Tandy for sticking to their beliefs and we have some of the finest Z80 based computers ever made in the Model 4 and 4P but faced with dwindling sales projections they decided to bite the bullet and produce a PC of their own but not just any PC this would be the super est PC of them all detail would be overlooked and every aspect of the computer needed to be an improvement on the IBM PC XT which was the version on the market in January 1984 but sell for around the same price as the IBM In November 1983 Tandy proudly announce the newest greatest TRS 80 yet the Model 2000 It would outdo IBM from every angle but had one major flaw it wasn t properly compatible it was only somewhat compatible The 2000 graced the cover of 80micro in January 1984 and in fact the computer was well received by the computing press TRS BIT VOLUME 027 ISSUE 02 JUNE 29013 PAGE 36 at the time who were growing bored of plain compatibles which did nothing in particular better than the IBM PC XT The 8MHz 80186 CPU had the 2000 running rings around the IBM the 720K disk drives held twice in information the IBM drives did and the display was sharper and if you went the whole nine yards and added hi resolution colour graphics and a CM 1 monitor you got 16 colour 640x400 graphics not related to VGA which was still 4 more years away which made the IBM s CGA 4 colour 320x200 graphics look positi
113. ance that in normal operation a bad bit might go unnoticed for months Keep this program running it will continuously loop for no less than 8 hours if you suspect x n n BEST 23223 or Table 1 Bit Search program VOLUME 7 ISSUE 44 DECEMBER 2013 bad bit It took 9 1 2 hours be fore conditions were right and the balky bit turned up in my tem The computer can be restored for normal use only by turning it off All system RAM has been upset by Babyrooting around 1 the RAM is too badly damaged Babyroot Mself may not load Vinte me for special version of the program for use in this case A Bit Error When youve discovered bad RAM what do you do A bit error i amp sophisticated enough problem you first want to leave it 10 your Ihendly Radio Shack repair center How ever i you find thes suggestion unappealing you ll want to tackle it yourself First you probably want to the bad bit s position in the byte Now that you know its ad dress Table 1 lists a short pro gram to identify that bit Enter the least significant byte of the bad RAM address in 2538 asss Spas 8s 38 PAGE 50 1o the position marked Enter the most significant byte into the position marked 4 You relocate this program any where in memory necessary to avoid baliky addresses Now set this program in motion A good byte
114. at goal We trust that in dealing with us you will find that friendliness has meaning and is not just a commercial platitude WARRANTY 3 months after date of shipment The only element which can fail is the motor We have replaced very few motors during the life of the product TRS BIT VOLUME 27 ISSUE 1 MARCH 2013 PAGE 10 ASSEMBLER NOTES Laurie Shields Introduction We have not yet succeeded in answering all your questions Indeed we feel that we have not yet answered any of them The answers we have found only serve to raise a whole new set of problems In some ways we feel we are as confused as ever but we believe that we are confused on a higher plane about more important things Assembler Programming One school of thought defines assembler programming as the nearest thing to the tortures of the Spanish Inquisition in its ability to deprive its sufferers from sleep and recognisable human social behaviour but this opinion cannot truly be relied upon because it totally disregards the self inflicting masochistic aspect of the disease Perhaps though we ought to at least consider how the external symptoms are displayed Usually they take the form of the sufferer ceaselessly keying in at the nearest computer some totally meaningless expressions that they fondly believe to be English type words and then asking the computer to change the words into equally meaningless numbers When finished the net effect of the
115. at the result is bigger than either of the two starting numbers and it has got set bits common to both The XOR instruction abbreviated from EXCLUSIVE OR means take the 1 s from either the first value OR the second value but EXCLUDE those where both values have a 1 and put the result in the A register 1 31H 0 1AH 0010101 1 which is 2B Hex this bit was excluded This operation can be considered most like a two way switch Any bits that are set in the second number will ensure that the result for those particular bits will be the dead opposite of whatever they were with the first number and visa versa The most commonly seen example is blinking star on the cassette load The AND instruction is simpler and means take the 1 s where they occur in both the first valve AND the second value with the result into the A register So we get 00010000 which is 10H this is the only bit set in 31H AND 1AH This operation is very akin to a filter Any bits set in one of the numbers that don t match those set in the filter are not set in the result Now part of the importance of these operations lies in the fact that the Zero flag in the F register is triggered to set or reset depending on whether the resultant value in the A register is zero or not Also as none of the three instructions can generate a carry condition the C flag is automatically reset irrespective of the final value TRS BIT VOLUME 027 ISSUE 02
116. ations in the COMM position it acts like a null modem adaptor has been added to the cable Finally the solder coated edge connector can oxidise like all connectors on the Model I and needs occasional cleaning with a pink pearl eraser If you have any questions concerning the serial ports on 8 bit TRS 80s feel free to drop me a line ianmGtrs 80 com REFERENCES 1 TRS8Bit March 2013 pp 6 8 2 http en wikipedia org wiki Universal asynchronous receiver transmitter 3 Radio Shack 26 1145 Model I TRS 80 RS 232 C Interface manual 1978 p 31 4 http en wikipedia org wiki Line driver 5 Model 4 4P Technical Reference Manual Tandy Corp Cat No 26 2119 1985 pp 142 3 4 2 16 RS 232 C Circuit 6 RS 232 Made Easy Connecting Computers Printers Terminals and Modems Martin D Seyer 1984 pp 77 88 171 173 7 http en wikipedia org wiki Null modem Ian Mavric is an IT Specialist who also restores and collects TRS 80 s and classic cars He live with his wife and kids in Melbourne Australia up TO SOMETHING SPECIAL OR NEW 2 TANDY YOUR TING US AL aBouT LETTING HOW KNOW ABOUT 9 TRS BIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 5 THE NEW POWER SUPPLY FROM THE RIGHT STUFF LOST ONE OR BOTH OF YOUR MODEL I POWER SUPPLIES ARE YOURS WORN OUT OR JUST PLAIN BUSTED DID YOU JUST BUY OR INHERIT A MODEL I AND IT DIDN T COME WITH THEM BUY THIS ONE IT
117. awing board to design the Model III it was clear that the large 50 way I O bus was designed around connecting a hard drive The Model III hit the showrooms in 1980 and the hard drive in late 1982 as our old favourite 5 Meg Disk System 26 1130 in RSC 8 Sept 1982 Something as expensive as a hard disk drive normally needs a killer app in order to hook in potential buyers and in the case of the Model III it was Profile III Plus HD and early database management system that was fast and with a hard drive capable of building enormous databases There was no such app for the Model I and since the computer had been forced into retirement in 1980 by the FCC Tandy could probably have overlooked making the hard drive work with the Model I and not many people would have cared This is where you see the clever minds at work at Radio Shack pulling yet another trick out of their hat for Model I owners small adapter kit called blandly enough the Model I Hard Disk Adapter Kit 26 1132 was sold for only 70 see below Once you own the hard disk you are kind of locked into the TRS 80 product for the next few years It is no co incidence that 5Mb hard drive works perfectly on the soon to be released Model 4 So what if the owner had a lot of money invested in their Model I and didn t feel like TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 24 buying a Model III no problem our next machine will blow your socks off and in addition yo
118. best in a TRS 80 system when working well they are a delight to use fast and reliable The average file size being so small on a TRS 80 most users would have a hard time filling a 15Mb hard drive let alone something larger like 40Mb If you have any more questions about how to repair or keep your hard drive operational or want one of your own feel free to drop me a line TRS BIT VOLUME 027 ISSUE 02 JUNE 29013 PAGE 23 NEXT TIME Project to build a Model 1 Power Supply Please email me at ianm trs 80 com REFERENCES 1 My Adventures with Hard Drives Part 8 Computer News 80 Vol 4 No 8 pp 19 23 2 http nemesis lonestar org computers tandy hardware storage mfm html 3 http en wikipedia org wiki Stiction 4 Radio Shack Service Manual 5 Meg disk system 26 1130 pp 27 29 5 http redhill net au d cl php Ian Mavric is an IT Specialist who also restores and collects TRS 80 s and classic cars He live with his wife and kids in Melbourne Australia from i AALGRAY Starquest by Automated Simulations ADVENTURES Death Dreadnaught 16k You are alone or are you on an alien spacecraft with signs of death and Please make cheques PO s payable to Algray Rescue at Rigel 16k Lil 12 96 32k TRSDOS 14 96 is Real time Graphic adventure into an You e pri You are equ with Power gun Blaster and Force shield But you Atian
119. bject code list ting tine and has for output tored either in VIDEOUT starting at line 8 is the important rou a few points of note Firstly the HL register arrives with the address of the start of the string of characters f The first character is loaded into the A register and immediately HL is incremented This is a fairly universal convention of maintaining a pointer be it s memory or in a register as always pointing to the next character Once the current character has been loaded or to memory or wherever required the pointer is TRS amp BIT VOLUME 7 and reference to it bumped to the next one ISSUE 03 SEPTEMBER 2913 from is no longer The output PAGE 17 subroutine is then called and whatever was in the A register is now on the video We know return wi whether it character h W I as a CR and if not Th ere is a weakness with Lor ou speak where we do not our VIDEOUT program each character execute an OR A command and if Now we meet one of the many aspects of for us We want to return if re makes Sel turn li i e tput mus ow when to stop nice if we could detect the end of friend zero is an easily detect printable character we can use it F want a CR We must immediately after Since o fe easy the equivalent of
120. c Capacitor 2 Fuses 250mA for A2 50 for 10 mE 240V 500mA for 120V on each transformer 2 Wg 3AG AGC Fuseholder A2 30 Each Optional 2 5 Pin DIN Line Plug A1 00 Each 1 PO4 6A 400 Bridge A2 25 Each Rectifier THEORY OF OPERATION Basically one transformer a 7 5 0 0 7 5 supplies the 15VAC output and the other transformer a 6 0 0 0 6 0 supplies a bridge rectifier and an electrolytic capacitor supplies the 19VDC supply The reason this is done is because the standard Single transformer inside an original TRS 80 power supply has two secondary windings to give two different output AC voltages from the 1 transformer The bridge rectifier changes the AC output to DC and the capacitor smooths out the ripple current coming from the bridge down to something palatable to the Model 1 The Model 1 itself due to its 1970s design is not very picky about how close to ideal the voltages are supplied to it it is more concerned about the AC and DC being fed so as long as 14 17VAC is supplied across pins 1 and 5 of the power connector and 19 21VDC is supplied across pins 2 and 3 the computer will run Since the power supply needs to work in either a 120V or a 240V environment Dean came up with two PCB artworks and two schematic diagrams the difference being how the primary side of the transformers is connected On the 240V version the TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 25 transformer pri
121. command RSFORM6 1 Prompt as follows at the process for remaining partitions ER RSHARD6 ER RSHARD6 ER RSHARD6 ER RSHARD6 anak age age Re ae ER RSHARD6 Disk pack name HARDA Password PASSWORD Manual Lockout N 5 Rep SYSTEM DRIVE 2 DISABLE DRIV SYSTEM DRIVE 3 DISABLE DRIV SYSTEM DRIVE 4 DISABLE DRIV SYSTEM DRIVE 5 DISABLE DRIV SYSTEM DRIVE 6 DISABLE DRIV each time specifying TRS amp BIT 6 heads and 136 cylinders VOLUME 7 ISSUE 1 MARCH 2613 PAGE 31 6 Format the partitions you just created RSFORM6 2 Prompt as follows Disk pack name HARDB Password PASSWORD Manual Lockout N RSFORM6 3 Prompt as follows Disk pack name HARDC Password PASSWORD Manual Lockout N RSFORM6 4 Prompt as follows Disk pack name HARDD Password PASSWORD Manual Lockout N RSFORM6 5 Prompt as follows Disk pack name HARDI Password PASSWORD Manual Lockout N GI RSFORM6 6 Prompt as follows Disk pack name HARDF Password PASSWORD Manual Lockout N 7 Relocate the Second Floppy Drive to 7 using the SYSTEM command SYSTEM DRIVE 7 DRIVER FLOPPY Prompt as follows I O ADDRESS 2 8 Perform a disk backup to the Hard disk to copy the files over BACKUP 0 1 NEW S I Q N 9 Identify the Hard Disk as the system disk SYSTEM SYSTEM
122. cts And wait for it it progresses to FOURTEEN levels of difficulty Mike s last words Nobody will ever get It s ONLY available direct from Kansas but at a there sensible 9 50 Vat and post paid As pulishers we do not retail other people s programs we have absolute quality control and thus give unconditional guarantee on all our software ri famed return first class post service whether ordered by cheque or credit card Ask for a copy of our free catalogue you won t find any South Coast prices therel Access and Barclaycard welcome nd of course all programs are always in stock for our MEUSE RA IG ERR ER E n Kansas City Systems Unit 3 Sutton Springs Wood Chesterfield S44 5XF Tel 0246 850357 HULLFORTH This new Forth compiler for NASCOM 1 11 is now also available for TRS 80 Level 11 and Video Genie HULLFORTH is a structured high level language which runs over 10 times faster than BASIC Runs in under 16K Supplied on cassette with full documentation Nascom users please quote NAS SYS or NASBUG Hullforth is a Nascom approved product Price 25 Send SAE for further information to Mr A F T Winfield 148 Goddard Avenue Hull HU5 2BP ISSUE 93 TRSSBIT VOLUME 27 SEPTEMBER 2913 TRS 80 MODEL I ENHANCED VIDEO TANDY COMPATIBILITY mode default gives lower case without the need for switches FULL MODE
123. d go back for the next character Nothing to it really so assemble it and jump to 7600H with breakpoint at 783CH to see it all work We can of course tidy up TEXTIN to a little subroutine that simply needs HL and C initialising to come back on return with the string input into the buffer and the number of characters in B TEXTIN LD B 0 KEYIN CALL KEYSCAN OR A CP CR RET 7 This is the exit from the routine CP BS JR NZ CHECK DEC B JP DEC HL LD HL JR PUTONVDU CHECK CP 32 JR C KEYIN PUSH AF LD A B CP C JR C NOTFUL POP AF JR KEYIN NOTFUL POP AF LD HL A INC HL INC B PUTONVDU CALL OUTPUT JR KEYIN That was the easy one in case you hadn t noticed now it gets a little bit trickier as the next problem is inputting numeric data Instead of any character from the keyboard we now only want to accept the digits 0 to 9 but once having keyed them in convert the digits in decimal format to a numeric quantity that the Z80 can understand Actually it s not going to be that bad considering what we ve already been through TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 13 First of all we can re use most of the preceding program for reading the keyboard with some additions and alterations to label names etc The first change is to reject any characters less than 0 with CP 0 rather than CP 32 we must also add an extra test to reject anything bigger than 9 so Check beco
124. d offer twice as many colors And all four of our user accessible slots are available for future growth Putting it simply the Tandy TRS 80 Model 2000 delivers extraordinary quality with higher performance than other popular computers including the IBM 128K 2 Disk Tandy 2000 26 5103 4450 00 Comparable IBM configuration win monochrome adapter and display communications adapter 256K 1 Disk Tandy 2000 With 10 Megabyte Hard Disk 320K disk drives and 128K RAM tManufacturer s pricing as of 21 6 84 DEED T ae cy ee 6950 00 TRS BIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 33 Designing revolutionary concept in software demanded a computer with extraordinary performance The Tandy 2000 delivered 5 5 Chairman of the Board Microsoft Bill Gates has been at the leading edge of personal com puting from the very begin ning His company is a leading producer of microcomputer software Our newest software product MS Windows is an in tegrated windowing environ ment It will let personal computer users combine indi vidual programs into a power ful integrated system When we set out to design MS Windows in color we knew that the Tandy 2000 com puter would let us turn an ex traordinary product into a work of art The graphics are sharp and crisp and gave us a degree of creativity like noth ing before Our engineers were quite impressed with the process
125. de Is the work and expense worth the et fort We think it is Getting rid of the heat and memory glitches was well worth it I PAGE 33 Virtual Floppy disk using a Raspberry Pi Alan Page Introduction to the project Last winter I started a project to create a Virtual Floppy disk emulator for the TRS 80 Model I using a Raspberry Pi The project was inspired by several similar projects based on Arduino and other micro Bcontrollers and because my ancient TRS 80 Model I was having problems reading and writing floppy disks as the electronics and hardware aged It s also rather difficult to transfer software to and from the TRS 80 without such a system The advantage of the Raspberry Pi is that it is a complete system with video USB keyboard mouse and storage support The disadvantage is that the current available operating systems are not ideal for real time But the hardware features of the processor help overcome that limitation as will be seen later TRS 80 Floppy Disk Interface Model I The TRS 80 Model I expansion interface which supported the first floppy drives for the TRS 80 was created around 1978 It was designed to use existing floppy disk drives with perhaps some minor customizations connected by ribbon cable to the expansion interface It used a Western Digital 1771 floppy disk controller IC which supported single density only running at a clock speed of 1 MHz The timing diagr
126. deo or onto the printer and both the source and Object files can be saved onto cassette and read back into memory The program is line orientated and so always maintains a pointer to the current line with the pointer movable by various commands The various debugger commands allow a great deal of control and are very extensive including Copy Goto Modify Fill Examine and Check User input can be edited and parameters can be either decimal hexadecimal or octal We believe this to be the best program of its kind on the market not only for its extensive features but for its ease of operation and especially for its price 19 50 Return first class post service Barclaycard or Trustcard accepted This program will run perfectly on the Video Genie as it does not utilise the right arrow key GRAPHICS ASSEMBLER 8 50 Assemble graphics in your Basic program in super fast machine language and by simple Basic statements That s what you can do with the Graphics Assembler This remarkable program will allow you to take a single line of any Basic program and pack it with machine I nguage graphics and control commands The program itself being in Basic means it can easily be incorporated in any of your Basic programs to give extended graphics capability without having to load the two separately And of course all kinds of animation of the graphics created can be obtained using the normal Basic routines All that
127. display Chess Clock Game record in standard notation on the screen and optionally on a printer Pleose send me Board set up for solution of chess problems Gombiet 80 on tope for the TRS 80 19 95 Toke back facility Toto _ _ Signoture Continual display moves being evaluated by the program Mate anticipation 4 5 E rt tick Creat CordNol1 T T T T TT TI CELI The fastest serious program for the TRS 80 or Video Genie Send to Microtrend Ltd P O Box 51 Poteley Bridge Horrogote North Yorkshire HG3 SDP Name Address ile a TRSSBIT VOLUME 7 ISSUE 2 JUNE 2913 PAGE 26 IN MAV S WORKSHOP by Ian Mavric HOW TO UPGRADE A TRS 80 HARD DRIVE To conclude this trilogy of articles on the TRS 80 hard drive I m going to talk about how to change the MFM hard drive in your TRS 80 5Meg 26 1130 or 15Meg 26 4155W unit to something else A large amount of the information in this article comes from the late Roy T Beck who wrote a ground breaking series of hard drive articles in Computer News 80 in the early 1990s These articles are very hard to find and so I am presenting elements of them here WHY CHANGE THE MFM HARD DRIVE The MFM hard drive has been installed in the TRS 80 5 or 15Meg disk system for around 30 years The Tandon TM602S 5meg and TM503 15meg drives were robust and reliable for the time but Tandon designed them with a 5 year lifespan which is a duty cycle of arou
128. dy mounted The Universal Spool MAC INKER base with the 1 2 width 5505 adaptor re inks the majority of all spools Some spools have large inner diameters The letters A or B etc refer to the centering adaptors required to mount the spools For example the 3262 spool uses the S606A adaptor where S means spool 606 indicates the 1 width adaptor and A the centering element Is re inking messy With a minimum of care it is possible not to touch the ribbon while mounting or removing the cartridge from your MAC INKER Ink is spensed from a drip cap bottle and or an eye dro for accurate metering First time users generally and naturally tend to rush Alcohol is a reasonably cleaner Soap will wash out the ink after 2 or 3 times We have found an excellent printing ink cleaner see price list in use with the Air Force We have put itin the price list as it is the best and gentliest ink cleaner we ever found It is also an excellent all round degreaser 8 Is any special care needed for the inking elements between re inkings No the lubricant in the ink will prevent a total dry out and the dot matrix ink contains no carbon or abrasives Just shelter the inking elements from excess dust The Inking elements life is practically indefinite pu begat ENG on teme dion waa M M n beginning A oz bottle will yield about 25 40 re inkings a 20 yards metering spout and ink will keep indefi
129. e the line number where it is defined and the line numbers of every reference to it in the whole of the source file Label value occurrence references CR 000D 3 50 83 BS 0008 4 52 HOWMANY 7819 1 7 6 NUMBUFF 782C 18 8 12 QUANTITY 7831 19 14 17 CONVERT 7833 21 13 TIMESTEN 783F 30 42 CONVERTEND 7852 43 28 NUMBERIN 7855 46 10 55 KEYIN2 7857 47 49 61 63 69 76 CHECKNUM 786D 60 53 NOTFUL 787D 71 67 NUMBVDU 7881 75 58 VIDEOUT 7886 78 7 84 OUTPUT 7892 86 75 82 KEYSCAN 789C 92 47 Anybody getting this far without the help of Assembler s Aspirin Pt No 26 XXXX at your local Tandy shop is entitled to celebrate Appendix 1 The following list is simply a catalogue of the Model 1 Rom calls that have come to my attention through various publications and other means Some of these may be Model 3 compatible and some are bound to be totally different Address Action Comments OOOBH Where am I Pops the return address into HL and Jumps to HL Used to determine where in memory you are CALL OBH HERE PUSH HL POP IX IX now has value HERE TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 19 LOOKING FOR FAST INEXPENSIVE UNLIMITED MASS STORAGE FOR YOUR TRS 80 MODEL VII1 4 4P 4D The amazing Emulates TRS 80 hard drive but faster than any hard drive Works with your favourite DOS LS DOS LDOS CP M Newdos 80 2 5 Uses SD card for storage medium Bonus free Real Time Clock function Designed i
130. e 150 ohm pull up resistors to 5v Only one drive should have the pull up resistors and generally it is the last drive on the cable I put a set of pull up resistors on my interface board and a jumper between the resistors and 5v from the Pi power supply The TRS 80 drive cable does not provide 5 volts so it s necessary to use 5 volts from the Pi board Not listed here are the ground signals from the cable which should be connected to ground on the Pi TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 37 n lt lt O c C e oi o 95 00 00000002 0 20 Y Y 1 Y Y Y 00900900 JjUJOQOOOOOO JU O t0 OO O y 20000 TRS BIT O0OO0OO0OO0OO0O0000009009000090907 This is a picture of the top of the original prototype plugged into the Raspberry Pi beneath it The IC on the left is a level translation board which I found was not necessary The connector to the Pi is at the bottom left The cable that connects to the Expansion Interface is at the top The resistors are pull up resistors and the yellow jumper connects them to 5v The board itself is just a plain prototype board with a cutout for one the Pi connectors that Sis too high for the pin header 200 20 000 0000900000 500000000 0009000009 0999909 0999090 0500900090090000 O 9000 79909 0000000009000999
131. e of the program when we set the breakpoint to interrupt it So until we have used the de bugger to jump into and break out of a program the values displayed by the X command are just as meaningless as telling the computer to PRINT Y would be before we ran the BASIC program that gave Y its value Just before we leave the registers we should note that as the register pairs HL BC and DE can perform as 16 bit registers it is possible for them to comprehend a number as big as FFFFH or 65536 and as little as 0 This makes them very useful in pointing to a particular byte in memory for storage or retrieval HL remember the pair with very little brain can also do adds and take aways in 16 bit arithmetic provided the other number is stored in either BC or DE PC program counter SP stack pointer IX and IY index registers are all inseparable 16 bit registers intended for storing memory addresses It is best not to try and grasp the whole complexities of the Z80 chip in one go Instead just get to know each register in turn as you use them in your programs To start with it is sufficient to know that A holds a small number and can do clever sums with the help of the F and that HL and BC can hold big numbers If we need to store a lot of small numbers HL and BC can be treated separately as H L B and C FREE Master and Editor Assembler By Laurie GET INTO MACHINE LANGUAGE EASILY SER from square one
132. easiest to get to know is the routine for printing a character on the video at the current cursor position and moving the cursor on to the next It starts at memory address 0033H and as the leading zeros aren t necessary it is nearly always referred to as simply 33H This routine will save us a lot of work as it not only finds the current cursor location puts our character there and increments the cursor but it also looks after any scrolling of the video that should be needed if we do any printing on the bottom line To use 33H we simply load the A register with the character we want to display and then CALL 33H On encountering our CALL instruction the Z280 pushes the address of the next instruction onto the stack so that it knows where to come back to and then it jumps to 33H and starts following the machine code instructions there Let s test this routine to prove that it really works Use R TRS BIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 7 to kill off any source file you have in memory and then enter the editor and key in the following code 1 TESTING ROM 33H 2 ORG 7800H 3 LOAD 7800H 4 7800 3E2A LD A 5 7802 CD3300 CALL 33H 6 7805 00 NOP 7 END The semicolon in line 1 is the Assembler s equivalent to REM in Basic and the NOP pseudo op generates a 00 byte which is a No Operation code as far as the 280 is concerned We ve put it there just
133. ecimal or 0000 0000 binary up to 255 decimal OFFH hexadecimal or 1111 1111 binary We have now gone and confused you by putting a 0 in front of the FFH and someone wants to know why Well the answer is relatively simple and it doesn t mean that we have squired an extra ninth bit of value zero it simply follows on from our normal programming convention that if something begins with a letter it is a variable and something beginning with a numeric digit is a number So to avoid any possible confusion we always well nearly put a leading zero in front of any hex number that begins with a letter Now this convention is purely one way is from human to computer This is because the computer cannot guess as to whether when we key FFH we mean a number a label or variable or just a plain expletive deletive When the computer is giving us information the assumption is made that we know what we have asked for and should recognise it when we see it So what happened after we keyed Q5712 Well the first thing Zen did was to check whether or not we had put an H at the end of our input Had we done so the Zen would have treated it as hexadecimal since there wasn t it was treated as an ordinary base ten decimal number and Zen turned the 5712 into hex and rounded the last digit down to the nearest 0 or 8 Decimal 5712 converts exactly to 1650 Hex in this case no rounding was necessary The letter Q was interpreted by Zen as a Query
134. ed annoying when it happens So whenever you are using the Load pseudo op ALWAYS check on memory usage to ensure you are loading into free memory Free memory being between the end of the source file and the top limit of high memory everything below the start of the source file is in use broadly as follows TRS BIT VOLUME 07 ISSUE 04 DECEMBER 2013 PAGE 11 Start Stop Used by 0000H 3FFFH Rom Keyboard video Printer etc 4000H 4350H Mod 1 4450H Mod 3 Level 2 cassette operating system 4450H Start of Source Cassette Zen Or for disc 4000H 51FFH DISC operating system 5200H Start of source Disc Zen Meanwhile back at the program TEXTIN starts with setting B to zero and calling the keyboard until a key is pressed Check first of all if it is the big white one as in that case we can pack up Next check for a back arrow as this is the only other key less than 32 that we will accept Now if it is a back arrow there are two possibilities either it is the first keystroke and there isn t anything there to rub out or it isn t and there is We will decrement B anyway and see what happens If B was zero to begin with then we dropped a clanger and it has gone minus so the simple way to recover is to jump back to the very beginning of TEXTIN and start afresh Note we have to use JP M instead of JR C as just DECrementing a register does not trigger the Carry flag If B hasn t gone negative then there must be a character to delete
135. ed in direct sunlight at some time in its life so both Enter keys were yellow and it had also lost its Model III nameplate After bleaching the Enter keys finding a spare Radio Shack TRS 80 Model III Microcomputer nameplate the computer was finished Not a bad start I thought Next I had a look at the hi res Model III and jeez they are TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 29 complicated beast The hi res board mounts to an aluminium chassis which sits over the motherboard It s all a very tight fit inside the cabinet Graham had modified his Model III with extra cables coming out of the hi res board I wasn t entirely sure what they were for but I m guessing to drive an external monitor perhaps for classroom presentations or the like The cables were a mess and once I had removed them all I had the hi res board removed from the machine At this point it s just a regular Model III 48K disk system which I powered up and it was in avery unhappy state Model IIIs have 24 16Kx1 bit Ram chips arranged in three banks of 8 chips each bank providing 16K of memory After some swapping and changing I ended up throwing out 14 bad Ram chips replacing them with good used one and finally after some hours was greeted with Cass on the screen The power supplies both Model III disk systems have dual 35W power supplies in them had blown A C line filter caps which were changed but the disk drives were both unhappy I sourced a
136. ed one of these for over 6 months now on my main daily use Model 1 and have had no bad side effects Others who have used the supply include David Cooper in Seattle WA and Andrew Quinn in Auckland New Zealand In addition Dean s design uses toroidal transformers which are the latest design in PCB mount transformers Moulded in blue plastic they are compact powerful and don t generate much heat vibration or electrical noise They are ideal for installation in the Expansion Interface as they won t cause it to overheat like the US 120V ones tend to do They also won t make your Model 1 display wobble all over the place PARTS LIST I bought all my parts for this project from Altronics www altronics com au but all the parts except for the two toroid transformers are easily bought from any electronics supplier in the world The toroid transformers are a little harder to locate but most countries will have a supplier who has them Also note with the toroid transformers you need the 30VA versions There are 10VA versions which are a little cheaper but will not have the capacity to power a TRS 80 Typeset text from your disks N W Unlike some computer typesetting services Quite simply we re the specialists in you ve seen advertised wordsmiths Anvil print for micro computer users service is ready for you if you use any of the For details of our typesetting print and other following machines services for the word p
137. el Labels or symbols can be called anything you like they can be as long as you like provided they begin with a letter and aren t one of the assembler s reserved words like END or LOAD etc 58 VOLUME 27 ISSUE 2 JUNE 2013 PAGE 7 In our BASIC program that we are going to copy the program keeps jumping back round in a loop until BC is exhausted so let us use the label LOOP To convey to the assembler that a particular collection of letters is to be referred to later we must add a colon immediately after the label as a means of declaring it to the assembler First GOLDEN rule of assembler programming You will never learn ANYTHING by reading until you have actually keyed it into the machine yourself So stop reading put the cat out switch on the computer get your copy of Zen and System load Run or Zen cmd now Make sure you have a clean cassette formatted floppy tape or disc with some room on it as we shall save the source file for future use From here on in lt E gt means the Enter TRS80 or New Line Video Genie key To switch Zen into the text entry mode key E lt E gt Enter the Editor Zen responds in a similar fashion to the AUTO mode in BASIC by printing the number 1 for the first line and waits for you to key in anything you like so key in the following except for the line numbers which Zen does for you 1 ORG 7800H E 2 LD HL 15360 E let HL 15360 3 LD BC 1024 E let
138. eleased the TRS 80 5Mb hard drive in 1982 LDOS was Tandy s official OS called HDOS at the time so there is a certain lineage which is why it works so well Just as NEWDOS 80 is probably the best certainly the fastest OS for a floppy based Model I or III LDOS is the best OS for a hard disk TRS 80 even though its floppy operation is slightly slower than NEWDOS 80 Conversely NEWDOS 80 can be set up ona hard drive but its complicated and in my opinion clumsy to use The choice of hard disk driver software I have similar views and the only one which consistently allows me to set up and use standard and modified TRS 80 hard drives is RSHARD5 6 by Misosys Again I ve been using it for more than 20 years and it has never let me down It s compact and bug free and very few programs have shown problems running software off hard disk with RSHARD5 6 residing in memory Radio Shack s drivers are suitable for use with hard drives with the standard 5Mb or 15Mb Tandon MFM drive installed but are somewhat limited beyond the capabilities of those drives other words if you modify your hard drive with a non original MFM hard disk you will need RSHARD5 6 TRSBBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 26 PARTITIONING THE HARD DRIVE Partitioning simply means dividing up the storage space on your hard drive Within that framework we have a number of limitations to work with and various ways to work around them RSHARD5 6 allows you to cu
139. emory space for storage As soon as we do this however we are then faced with making sure that the number of characters keyed in does not exceed the size of this buffer Just to keep up the excitement we must also provide a prompt on the video such as Enter Name we must make sure the rest of the line has been blanked out before we ask for keyboard input and last but not least make sure the cursor is switched on Don t laugh just see Zap 22 in Apparat s Newdos80 version 2 for their Edtasm fix A crafty peek at your Level 2 manual gives us the three very useful numbers 14 30 and 31 The value 14 will switch the cursor on 30 will clear from the current cursor position to the end of the line and 31 will clear from the cursor to the end of the video We will use just 14 and 30 for the time being Taking our previous routine we can easily alter it to display our new message ENTER NAME but lets add the 14 and 30 to the message and see what happens We may as well add the storage buffer as well which introduces us to a new pseudo op DS or DEFS for Define Storage This must be followed immediately by the number of bytes to be reserved so let s fix it now at say 25 bytes just under half a line Now we get the tricky bit We will use the C register to hold the maximum number of characters to key in and HL will have the address of the buffer so it goes like this Set B reg equal to zero call keyboard and wait for key to be
140. en this before where the control just seizes up inside and there is little you can do other than replace the control with a good used one Once again the lid was removed from the computer and the faulty brightness control replaced Satisfied everything had been done to make this computer happy again I put it together one last time and that is how it is now at Ivan s 58 VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 39 The last Model III It was missing many parts had no disk drives and no power supplies installed it also had major scratches in the silver paintwork on one side and so I pretty quickly realised this one was going to be a parts machine to fix other TRS 80 Model IIIs Key switches from it were used to fix the 16K cassette machine and RAM chips control and various other screws etc were used to fix the hi res Model III brightness Some parts were used to fix the Model 4 which I will talk about next time Ian ianmGtrs 80 com 1 phi HOBBYIST GENIE em e Latest version of Video Genie now with upper and lower case letters Over 15 000 Bytes of memory for user programming excellent extensivable microsoft basic fitted with sound and joy sticks Package also includes user manual basic reference manual programming for beginners book cassettes with games useful routines educational orograms and demonstration programs blank cassette for user program cleanin
141. epresented by F Crib Sheet for the newcomers Decimal 0123456789 1 Hexadecimal 0123456789 01112 13 14 15 A B C D E F Even Better Crib Sheet for beginners and experts UNITS Ascii Value Tens 0 1 2 3 4 5 6 7 8 9 00 00 01 02 03 04 05 06 07 08 09 Printer amp 10 0 OC OD OE OF 10 11 12 13 Display 2014151617 18 19 1A 1B 1C 1D Codes 30 1E 1 202122 23 24 25 26 27 1 45 amp 40 28 29 2A 2B 2 2 2E 2F 30 31 01 50 32 31 34 35 36 37 38 39 3A 3B 23456789 60 3C 3D 3E 3F 40 41 42 43 44 45 lt gt 7 ABCDE 70 46 47 48 49 4A 4E 4C 4D AE 4F FGHIJRLMNO 80 SO 51 52 53 54 55 56 57 58 59 PORSTUVWXY 90 5B 5C 5D 5E 60 61 62 63 Z abc 100 64 65 66 67 68 69 6A 6B 6 6D defghijklm 110 6E 6F 70 71 72 73 74 75 76 77 nopgrstuvw 120 78 79 7A 7B 7C 7D 7E 7F 80 81 xyz 130 82 83 84 85 86 87 88 89 BA BE 140 8C 8D 8E 8F 90 91 92 93 94 95 Graphic 15096 97 98 99 9A 9B 9C 9D 9E 9F Codes 160 AO Al A2 A4 5 6 A7 AS A9 128 to 191 170 AA AB AC AD AE AF BO B1 B2 B3 180 BA B5 B6 B7 B8 B9 BA BB BC BD 190 BE BF CO C1 C2 C3 C4 CS C6 C7 Space TRS BBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 13 200 CB C9 CA CC CD CE CF DO Compression 210 D2 D3 D4 D5 D6 D7 D8 D9 DA DB Codes 220 DC DD DE DF EO El E2 E4 E5 192 to 255 230 E6 E7 E8 E9 EA EB EC ED EE EF 240 FO Fl F2 F4 F5 F6 F7 FS F9 250 FA FB FC FD FE FF In one eight bit byte we have the ability to store any number from 0 decimal hexad
142. er you like An interesting side effect of this is that it doesn t take long to realise that you install two operating systems and have two boot disks one for LDOS and one for LS DOS So you aren t then restricted to having your hard drive set up for Model III or 4 mode you can boot Model 4 mode LS DOS for serious work like Multiplan Superscripsit and Profile 4 Plus and boot LDOS to run your favourite Model III mode games Here s how its done Let s say we have a standard Model 4D and a 5meg hard drive with 4 partitions TRS BBIT VOLUME 27 ISSUE 1 MARCH 2013 PAGE 29 Starting in Model 4 mode we format all 4 partitions install LS DOS in partition 1 Disable partition 2 that s where LDOS will go so we have 3 partitions and 2 floppy drives and SYSGEN your boot floppy label it Model 4 HD Boot Boot LDOS and bring online all 4 partitions and install LDOS on partition 2 Disable partition 1 which is where LS DOS is and not needed for Model III mode so again we have 3 partitions and 2 floppy drives and SYSTEM SYSGEN DRIVE x your boot floppy label it Model 3 HD Boot What you have now is made the opposing DOS invisible to each operating system so both can co exist on the hard drive but not over write or interfere with each other A lot of commands in each DOS have the same names so if you were to accidentally issue FORMAT from LDOS while in LS DOS mode the system will error out Two of the hard drive partition
143. ewdos 80 2 5 Uses SD card for storage medium Bonus free Real Time Clock function Designed in Belgium and proudly built and shipped from Australia Kit form or fully assembled Order yours today http ianmav customer netspace net au trs80 emulator TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 15 Putting it on the Video Now that we are all at more complete routines first as that s the eas The simplest technique ending with a carriage abbreviated Assembler Basic for allocating a Chapter 7 home calling the ROM lets develop a few to display and input messages y one Display involves a straight forward message return or CR as it is usually has a command similar to the LET in value and takes the form EQU In future we will always refer to ASCII 13 as CR and use the EQU pseudo op at the beginning of our programs to initialise it OK we want to display a machine code masterpiec will have to have these to refer to them so we message say PRESS ENTER in our e Obviously somewhere in memory we 11 characters stored and we will need will use the label MESSAGE to have the start address of the me letter P Since our p messages of differing lengths we must include some means of identifying the end of will use the CR Review the problem 1 Put the characters memory 2 Sta
144. f Mac Inker price list 5 What happens if the ribbon is overinked There is no damage but the print out may be too dark or there may be some bleed through if the paper stock is thin Recovery is simple if required Wrap the ribbon around a paper towel roll amp let the ribbon make a loop releasing the excess ink onto paper With a minimum of patience and by reading the instructions anus 4 ctically impossible A properly re inked ribbon does not appear significantly different from a dry ribbon After the first re inking you will have an immediate feel for when the ribbon is properly inked One full ribbon pass around the inking element is generally enough 6 What does it mean Universal Cartridge and or Universal Spool MAC INKER The Universal Cartridge MAC INKER consists of a Universal Base UC and individual Driver Kits for the various Cartridges They fit into one of the 2 bi directional motor drives Pl refer to the beginning of the Price List A U after the model means that a Driver Kit is available for that printer Note that there are overlaps that is the same driver kit supports cartridges of different names and different extemal characteristics For example you wish to re ink Epson 80 esp 100 and Toshiba 1350 cartridges You need the Universal Base with the 271UK Epson driver and the 287UK Toshiba 1350 driver Mounting or oed m drivers is a matter of seconds However we normally ship the MAC INKER s with a driver alrea
145. f the next This they did by adding 126 or 80Hex to the first letter of each word and then simply by testing if any letter was bigger than 127 they knew where each word started and so to get the correct spelling all they had to was deduct 128 to obtain the correct Ascii value This in machine code is the equivalent of starting every word with an enormous capital letter Now adding subtracting and testing for this magical 128 is not very difficult in machine code as it depends solely on whether Bit 7 is set or not a condition that is very readily detected with the Z80 chip So Zen will tell us anything we want to know about the memory in our TRS80 just key the letter Q followed by the address and there it all is If you want the next 64 Bytes there s no need to give the address again as Zen remembers where the last block finished so just key Q lt E gt Should you require a printout of the Q display then key Shift instead of and the display will be routed to the lineprinter driver in Zen TRS 80 LETTER WRITER Compiled word pro cessor 12 95 Phone 082584 603 even ings for details SIMPLY SOFT 109 South Street East Hoathly Lewes Sussex TRS BBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 15 Chapter 2 Now what on earth are we to make of the second part of the display HL DE BC AF RI IX SP PC 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 5514 402D Well lets think of a B
146. flag is set 1 otherwise it is reset 0 5 Instead of executing the next instruction the program can jump to a different location that has been identified with a label The next few pages are going to be the hardest to grasp for some time so make sure you ve got some peace and quiet before you start and until you ve grasped OR XOR and AND you ll never make the grade These three very powerful instructions do Bit by Bit checks and comparisons between the A register and some other data The other data can be virtually anything from a fixed numeric value the contents of any register including the A itself or the contents of a byte in memory pointed to by either the HL or one of the index registers IX or IY Let us assume that the A register contains 49 decimal and we will see what happens if we carry out OR XOR and AND with 26 decimal Now 49 Dec 31 Hex and 26 Dec 1A Hex As the instructions are going to operate at Bit level we had better convert to binary 0 s and 1 s 49 Dec 31 Hex 00110001 26 Dec 1A Hex 00011010 With all three instructions we ignore the 0 s and fix our minds on the 1 s 58 VOLUME 07 ISSUE 02 JUNE 2013 PAGE 14 The OR instruction means take the 1 s from either the first value OR the second OR both and put them in the A register So we get 0 OR 0 0 0 1 1 1 0 1 1 which is 3B Hex 1 31H 0 1AH Its something like the lowest common multiple In th
147. g tape leads for second cassette and monitor Ready to plug in 1 Year s parts and labour guarantee Send cheque for E395 which includes VAT and carriage Delivery usually within 10 days ComServe 98 Tavistock Street Bedford Tel 0234 216749 TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 31 INNOVATIVE TRS 80 SOFTWARE FROM THE PROFESSIONALS We are pleased to be able to announce the commencement of a new series of Adventure games The series named Mysterious Adventures is written in machine language by B Howarth an English author The first episode is entitled The Golden Baton The scenario that you have been sent by the ruler of your own land to a strange province with the mission of discovering the whereabouts of the legendary Golden Baton of Ferrenuil King of the Ancient EIf Kingdom The baton mysteriously disappeared several years ago and whilst others have ventured to the land in an attempt to discover it none have returned to tell their tale The program foilows what has become the normal structure for Adventure programs Like the original main frame Adventure directions Gesignated by just the first letter of the compass point and commands may be optionally entered with jus t three letters of the appropriate word As usual provision is made for saving the game at any stage and such standard commands as Help Inventory Score and Quit are all available Experienced adventurers wil in vitably draw com
148. ggie I just put the later EI away and used the early buffer box version all these years Note to self investigate in the future That future arrived when we were trying to make the FreHD hard drive emulator work with the Model I I noticed the same problem if I set the FreHD up on a Model I based around a buffer box EI then I could configure boot disks easily When I went to do the same thing on a similar system based around a late EI the same problems showed up as using a real hard drive At least we know the FreHD emulates a TRS 80 hard drive so closely even its foibles are shared THE TEMPORARY SOLUTION turns out to be a bit awkward but does work Plug in an early buffer box EI and create your boot disk then replace it with the later model EI That way you get the reliability of the later EI and hard disk storage To backup the boot disk you DON T need to plug in the old buffer box EI just QFB 6 7 and it will backup the disk without hesitation TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 26 MODERN REPLACEMENT FOR THE 1 HD ADAPTER Over the years people asked me about adding hard drives to their Model Is and my usual response was Sure Go find a M1 HD adapter kit 26 1132 and we can get started I think two or three came through my workshop between 1987 and 2013 This year with the popularity of the FreHD hard drive emulator people began asking us about making a FreHD version for the Model I but to my mind this
149. gives the FULL CHARACTER SET in POSITIVE and INVERTED VIDEO and all graphics characters WHOLE SCREEN INVERSION including borders is independently controllable Double width capability is not affected Mode selection by port FE Fits inside the keyboard case Technical manual with software patches 6 Assembled and tested PCB 2102 chip 23 Parts and manual ordered together 26 45 The above Prices include worldwide postage and United King dom VAT Dealer discounts Installation available please enquire RHA MINISYSTEMS LTD 83 GIDLEY WAY HORSPATH OXFORD OX9 1TQ Tel 08677 3625 PAGE 22 IN MAV S WORKSHOP MODEL 1 TOROID POWER SUPPLY PROJECT HARDWARE PROJECT FOR ELECTRONICS ENTHUSIASTS by Ian Mavric words and Dean Bear design ASSEMBLY PROJECT Legal note if any of the following terms alarm you please get a professional to build the power supply for you Lethal Voltages Poisonous corrosive PCB etchant hot soldering iron possible damage to computer or yourself if built wrong the authors and editor bear no responsibility and make sure building a power supply like this is within your skill set PREAMBLE The TRS 80 Model 1 uses an external power supply to bring the mains AC voltage 120V in the USA and 240V in Australia UK down to approx 15VAC and 19VDC to power the computer If you have an Expansion Interface you need a 2nd one of these power supplies The power supplies themse
150. hat doesn t allow you to hold down a key you d have to stab the key repeatedly to move 5 the 1024 characters of the screen memory are from 15360 to 16363 so I can PEEK at that to see if there is a missile at the point where I m about to draw the player to detect a missile collision 6 PRINT moves the cursor to a new line unless you terminate it with a If you PRINT on the last line of the screen and don t use then the screen will scroll I use this functionality to scroll the screen and therefore animate the game Because the player is on the top line it disappears so I don t need to blank it out before I draw it at the new position Both of these give me very cheap animation If I d had it scrolling the opposite way missiles coming down at you then it would have been much harder and indeed I wouldn t have been able to do it without using machine code I know I tried Back in the day I ended up writing some machine code libraries to scroll the screen in an arbitrary direction and it still wasn t quite as fast Anyone else want to have a go writing a game in this severely limited medium TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 49 Here s a guide to the BASIC http www trs 80 com trs80 info level2 htm These give details of that keyboard map http home online no kr lund Genial_Joystick htm http www classic computers org nz system 80 manuals tm3 page21 jpg http www cla
151. he backwards compatible nature of some newer more readily available UARTs can help us out The TR1865 which is found in the 4P and gate array 4 and 4D just drops in and works a treat Another device you may see is by SMC called the COM8017 and COM8018 these work fine with the Model I and also can be used to substitute a failed UART in all Model III 4 4P and 4D TRS 80s The only thing you actually need to remember about UART chips on TRS 80s is that the TR1602 will only work on the Model I I ve tried it on a Model 4 it doesn t OTHER AREAS FOR CONCERN ON THE MODEL I RS232 There are a couple of other things which can go wrong with the Model I RS232 and I ll cover them quickly Sometimes Y1 the 5 0688MHz crystal can cause problems if it doesn t work everything will appear dead because the BRG uses it for timing the baud rates Also L1 and L2 circular induction loops can cause a short when they are bent over this isn t really a fault but the exposed legs of the inductors when bent over lean against the exposed circuit traces on the component side of the board so check them carefully and straighten them out This problem comes from rough handling of the board when its not installed in the EI The TERM COMM switch causes TRSSBIT VOLUME 27 ISSUE 03 SEPTEMBER 2613 PAGE confusion sometimes as it switches the polarity of pins 2 and 3 on the RS232 In the TERM position the RS232 acts as per standard specific
152. ickly see three extra components on the early version R10 R11 and C9 Examination of these parts revealed that they are required to feed 5V to Pin 10 of the BRG U10 10 The early BR2941 BRG needs 5V on U10 10 but the later BR1941 BRG doesn t Examination of the data sheets for the two BRG s shows that this is the only difference Terry tested this theory by installing a BR1941 in the early board with Pin 10 bent out it didn t go into the socket and it worked Wanting to set some steadfast rules for replacing the BRG in the future I compared the data sheets for a number of compatible devices including the COM8116 COM5016 AY 5 8116 and the WD1943PD which is the in the Model And while the all vary in capabilities they are all backwards compatible with the BR1941 2941 So I have summarised it in this statement When replacing any BRG in any M1 RS232 board with a modern equivalent always bend out Pin 10 I tested this first by installing the BRG out of an unused 4P motherboard I had in my parts bin and it worked and then I bought some COM8116 BRG s off eBay and tested one of those which also worked COM8116 seems to be the most common BRG available for purchase online TRS BIT VOLUME 07 ISSUE 01 MARCH 2013 PAGE 6 NEXT TIME I will discuss issues pertaining to the Uart Line drivers and other aspects of the M1 RS232 board ianm trs 80 com REFERENCES 1 http ianmav customer netspace net au t
153. ie a simple device It is made of metal has a small drive motor an inking head and it is designed to hold a specific ribbon cartridge x mount our cartridge gu ri i the ink 14 turn on the motor and leave it alone for about 20 minutes That s all The ribbon is now ready to use after it has had a chance to dry slightly We have been using one for six months re inked at least 40 ribbons and are still on our first bottle of ink refills are EI You can also get 2 blue green own yellow purple orange gold sar We find that our printers work fine and there is no build up of residue or ink the sure to specify ed nker you get will fit your ribbon cartridge or spool It is well built works saves money and is easy to use Buy one Cameron C Brown June 1983 page 103 This review covers our very first model before the advent of the Univer Macinker and of course does not describe the many improvements made since then NOTES amp COMMENTS TYPICAL QUESTIONS AND ANSWERS The review on the left published in BASIC COMPUTING was Mac Inker s first June 1983 Since then MAC INKER has been reviewed with equal enthusiasm by a t number of major magazines We hit a peak of fame when the New York Times and the Chicago Sun Times gave the Mac Inker an excellent review in the computer section We have a collection of over 700 unsolicited testimonials We wish to quote from
154. ing speed of the Tandy 2000 s 80186 microprocessor too And while the finished product will utilize the 2000 s Digi Mouse the well laid out keyboard has helped us speed through the design stage proud of our work So when we want to show someone how great MS Windows really is we give them a demonstration On the Tandy 2000 Isn t it time you enjoyed peak performance from a ADVANCED T OGY TRS BIT Bowl s watch how much faster todays most sophisticated programs run on the high technology Tandy 2000 You can choose from the hot test programs around thanks to our exclusive Express Order Software service Tandy 2000 systems start at 2999 and can be leased for only 105 per month Come in today and see what you ve been missing Engineered for Excellence We ve introduced the latest in technology for over 60 years The Tandy 2000 offers twice the speed graphics resolution and disk storage of other MS DOS systems VOLUME 27 ISSUE 2 JUNE 2013 Available at over 1200 io Shack ter Centers and m Radio stores and deai Radio COMPUTER CENTERS A DIVISION OF TANDY CORPORATION Mail To Radio Shack 85 A 564 300 One Tandy Center Fori Worin Texas 76102 EE COMPANY _ ces STATE __ ZIP TELEPHONE ___ Gath d Week ed
155. int head 2 How can a ribbon last so long It is a matter of cooling fabric suppleness and probability During a complete loop any one point of the ribbon is not even statistically struck once en it were the febri has time to cms from hour before the same point passes again in front of the print head A ribbon regularly re inked with lubricant carbonless ink will remain supple will not fray and the ink will help cool needles where the temperature can reach 480 degree F Our ink complies with or exceeds manufacturer s fabric ribbon ink spe lions For those interested we have a paper on the physics and the chemistry of inks and their interaction as well as on data from tests conducted at Computer Friends and at the University 3 How do recognize a fabric from a carbon ribbon Carbon ribbons cannot be re inked or rather re carbonized The is one way only When the take internal reel is full the ribbon cannot be re wound Fabric ribbons in ave 4 How do know when the ribbon has made a complete loop Here is a tip Prior to your first re inking amp using correcting fluid liquid paper dab both sides of the Start the MAC INKER motor amp measure how long it takes for the mark to re emerge from the other side of the cartridge This will give the correct From now on use a timer or alarm etc We can supply a good quality heavy duty AUTOMATIC SHUT OFF PLUG IN TIMER see back o
156. ir efforts is to achieve the same result as switching the computer off but without the benefit of saving any electricity Some of the more expert practioners in the art form have even been known to fill the video picture with one thousand and twenty four characters and generate a buzzing noise as the penultimate climax to their hours of unceasing toil Ordinary BASIC programmers who can t get beyond fifty Q characters before the dreaded Out of String Space appears on their videos go in awe and trembling before the amazing powers of the assembler The following pages on assembler programming and machine code in general on the TRS80 are the result of some considerable pressure from Brian to put down on paper the content of some of the talks and discussions on Zen that have occurred over the past eighteen months I am deeply indebted to a large number of people especially John Hawthorne who wrote the original Zen and also to Radio Shack for producing the TRS80 and Scripsit as well as countless others who gave me help when I started and didn t know the difference between a Byte and a Bootstrap Laurie Shields Chesterfield September 1981 TRS BIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 11 Chapter 1 get the best use from these notes you really ought to have a live TRS80 with Zen powered up and working As there are a number of different versions of Zen with differing degrees of sophistication I shall try t
157. isplayed To add 128 or 80H to an ASCII character causes just the seventh bit to become set everything else stays the same so by simply testing the condition of Bit 7 will be enough to indicate the end of a string We must of course make sure that we clear this bit before we try to display the character otherwise we would get some weird graphics instead of letters Obviously our display routine is going to get a little bit longer and more involved but the reward is in the saving in memory by not needing an extra byte with every message So once again we will rewrite our simple example 1 ORG 7800H 2 LOAD 7800H 3 7800 210778 LD HL MESSAGE 4 7803 CD1278 CALL VIDEOUT 5 7806 00 NOP For Breakpoint 6 7807 50524553 MESSAGE DB PRESS ENTE R 80H 6 7808 5320454E 6 780F 5445D2 7 7812 VIDEOUT LD A HL 8 7813 E67 AND 7FH 9 7815 CD1E78 CALL OUTPUT 10 7818 CB7E BIT 7 HL 11 781A 23 INC HL TRS amp BIT VOLUME 7 ISSUE 93 SEPTEMBER 2913 PAGE 20 12 7818 28 5 JE 2Z VIDEOUT 13 781D C9 RET 14 781E D5 OUTPUT PUSH DE 15 781F FDES PUSH IY 16 7821 CD3300 CALL 33H 17 7824 FDE POP IY 18 7826 D1 POP DE 19 7827 C9 RET 20 END Line 7 looks interesting and may take some working out First of all the CR has gone just to make it easier to explain DB PRESS ENTE R 80H the fun comes after the comma R 80H Well here is the best explanation you re going to get As we
158. ith as little 1 partition it s in our interest to have as many as possible USE THESE RULES TO DETERMINE HOW TO PARTITION YOUR HARD DRIVE SMALLER DRIVES PARTITION BY HEAD example 1 On smaller drives the simplest way to set up partitions is to allocate a head and therefore all the tracks under that head to that partition So on a 5Mb TM602S which has 4 heads the 4 partitions each have one head reading 153 tracks It s easy to remember your partitioning because a hard drive has a fixed number of tracks and heads If you lose or ruin your HD boot floppy it s easy to deduce that on a drive which has 4 heads TRS BBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 27 and 153 tracks per head each partition will be 1 head with 153 tracks This is in fact how Radio Shack set up their hard drives from the factory and it works well for hard drives in the 5Mb 10Mb 12Mb and 15Mb range Notice I didn t say cylinders cylinders represent all the tracks which carry the same number on each drive platter see diagram Track X Platter 1 Platter 2 Platter 3 Platter 4 Cylinder X LARGER DRIVES PARTITION BY CYLINDER example 2 On a drive with more than 406 cylinders even if you wanted to partition it by head you are restricted by Rule 2 so unless you wish to give up a large proportion of hard drive space partitioning by cylinder is the only way to achieve this Say you have a ST 251 40Mb which has 820 tracks a
159. ith graphics How to do it you will find out later TRSBBIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 9 Meanwhile the video is displaying Z gt which is Zen s way of saying Master I am here to do your will What is your command We must now understand that Zen has got a singularly one track mind when it comes to manipulating source code If we want Zen to display print or alter any line we have to tell Zen in simple language whether to go to the Top line or Up so many or Down so many lines To review our text which conveniently is less than one video page enter the following T lt E gt This tells Zen to point to the Top line lt E gt Enter by itself tells Zen to clear the Video P13 lt E gt Print thirteen lines At this point lets assume that we have an error in line 4 say there s a semicolon instead of a colon How do we fix it First get Zen s mind concentrating on line 4 by keying U9 lt E gt Up nine lines and line four is displayed Now key N lt E gt for New and depending on what version you have either line four will be zapped and you can key it in afresh or it will be displayed with the cursor at the end so you can backspace to the error and retype the line from the error onwards Our program should now look like this ORG 7800H LD HL 15360 LD BC 1024 LOOP LD HL 161 INC HL DEC BC LD A B CP 0 JP NZ LOOP LD A C CP 0 JP NZ LOOP END I Q x
160. ld start at zero after the first DJNZ would get the value 255 and we would do the conversion on the whole two hundred and fifty six bytes starting at the buffer address and ending up who knows where We can handle that though by checking on B first so putting it all together with a prompt say ENTER QUANTITY it looks like this 1 ORG 7800H 2 LOAD 7800H 3 CR EQU 13 4 BS EQU 8 5 6 7800 211978 LD HL HOWMANY 7 7803 CD8678 CALL VIDEOUT 8 7806 212C78 LD HL NUMBUFF 9 7809 0 05 LD C 5 10 780 CD5578 CALL NUMBERIN 11 780E 00 NOP For breakpoint halfway 12 780F 212C78 LD HL NUMBUFF 13 7812 CD3378 CALL CONVERT 14 7815 223178 LD QUANTITY HL 15 7818 00 NOP For Breakpoint 16 17 7819 454E5445 HOWMANY DB ENTER QUANTITY 14 30 0 17 781D 52205155 TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 16 17 17 17 18 19 20 21 22 23 24 25 26 27 28 29 30 sal 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 7821 7825 7829 7831 7833 7835 7836 7838 7838 783C 783D 783F 7840 7841 7842 7843 7844 7845 7848 784 784B 784D 784E 7850 7852 7854 7855 7857 785A 785B 785D 785F 7860 7862 7864 41 4E5449 5459203A 0 1 00 NUMBUFF 0000 QUANTITY FDE5 E5 FDE1 210000 CONVERT Check first if B 0 i e 76 B7 2813 E5 D1 29 29 19 29 FD7EO00 D630 1600 19 FD23 TOED FDEI C9 TIMESTEN 0600
161. licable The VIDEO GENIE SYSTEM offers outstanding value for money a complete system with Microsoft BASIC 16K of RAM and internal cassette ready to use for just 325 00 plus VAT Including full manuals interconnecting leads and a demonstration tape The System is easily expanded to a full 48K twin disk Business System including printer monitor and cables for around 1500 plus VAT Value indeed The System is available nationwide for full details and a list of dealers Contact LOWE ELECTRONICS CHESTERFIELD ROAD MATLOCK DERBYSHIRE TEL 0629 2430 2817 TRSBBIT VOLUME 27 ISSUE 1 MARCH 2013 PAGE 22 The BEST in TRS 80s Call The Right Stuff Ask for Ian The number is 61 416 184 893 That s The Right Stuff And he s in Melbourne http ianmav customer netspace net au trs80 TRSBBIT VOLUME 27 ISSUE 21 MARCH 2013 PAGE 23 KEYBOARD PRACTICE THE GRAND KIDS HAVE BOTH THE BOYS THAT ISO JOINED THE CLUB AT THEIR SCHOOL AND ARE FINDING THE PC S KEYBOARD LAYOUT SOMEWHAT CONFUSINGe I BRIEFLY TOLD THEM ABOUT THE ORIGINAL REASON FOR THE QWERTY LAYOUT SHOWING HOW THE KEYS COULD JAMB ON MY OLD TYPEWRITER AND I M SURE THEY WERE BOTH SUITABLY UNIMPRESSED THEY DO MANAGE REASONABLY WELL BUT I THOUGHT IF FINDING THE CORRECT KEY CAN BE FUN IT WOULD MAKE REMEMBERING THAT MUCH EASIER 50 I CAME UP WITH AN IDEA WHICH I THOUGHT MIGHT HELP I WANTED THE BOYS TO PRESS A SPECIFIC CHOSEN KEY WITHO
162. lves are very simple and for the most part very reliable Most were made back in the 1970s and still work now Radio Shack made the US 120V power supplies and Ferguson in Terrey Hills NSW made the 240V ones supplied with Australian Model 1s Ira from www trs 80 com had been emailing me about the growing number of requests he had been receiving for an alternative power supply for people who needed them It turns out there was a large number of enthusiasts out there who had either lost their power supplies or their great eBay purchase didn t come with them or they only had 1 and needed 2 to run an Expansion Interface or their own supplies had just plain worn out and failed Ideally an over the counter wall wort type power adapter would be great but due to the dual output voltage of the original power supply this is not possible or convenient I decided the best course of action was to design a supply based around 2 transformers each providing one of the two voltages needed that had enough power to run both the Model 1 computer and Expansion Interface but was compact enough to fit inside the Expansion Interface if needed A great side effect is that only one mains outlet would be needed instead of two TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 23 Dean Bear a TRS 80 enthusiast from Canberra came up with a simple design that meets all the design requirements above and all the parts are easily obtained I have us
163. m the disk R W head that has been transformed from the raw analog signal to digital pulses by circuitry in the floppy disk drive Because drives may vary slightly in speed from the ideal 300 rpm the floppy disk controller is somewhat tolerant of variations from the ideal signal My system has an add on data separator board from Percom that improves the performance in this area Because more than one floppy drive can be connected to the cable a drive should only pull an output signal low when it has been made active selected by the drive select signal The TRS 80 supported up to four drives numbers from 0 to 3 The input signals are Drive Select 0 Cable pin 10 Selects drive 0 when active In an actual drive this would cause the R W head to press against the disk surface DSO on the schematic Drive Select 1 Cable pin 12 Selects drive 1 when active DS1 on the schematic Drive Select 2 Cable pin 14 Selects drive 2 when active DS2 on the schematic Drive Select 3 Cable pin 32 Selects drive 3 when active DS3 on the schematic Motor On Cable pin 16 Turns all drive motors on The emulator should only be transmitting track data on the Read Data pin and accepting data on the Write Data pin when both Motor On and the appropriate Drive Select signals are active The expansion interface contained a timer circuit that would automatically shut off this signal after a few seconds if the Operating system was not using the drive interface
164. machine code programs will go to your routine that is the DCB at 4026H and all printing treatment printer from all that do their printing properly by calling the ROM TRS BIT VOLUME 97 ISSUE 3 SEPTEMBER 2913 PAGE 9 The BEST in TRS 80s Call The Right Stuff Ask for Ian The number is 61 416 184 893 That s The Right Stuff And he s in Melbourne http ianmav customer netspace net au trs80 TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 19 So what happens when we call 33H Well the Rom loads the DE registers with the address of the Video DCB 401DH and jumps to a sort of DCB handler routine that looks at the DCB checks on whether it is input or output most of the other registers are saved on the stack the actual driver program address is loaded into HL and then we jump to where HL is pointing On return all the saved registers are restored and we are back to our program except that DE is different This highlights one of the problems of using somebody else s subroutines in that occasionally they use some registers changing the values in them that we had put there and then not restoring them on the return to our program We must therefore be very certain before we use any ROM routines which registers they use and whether or not they are restored on return Now if we refer to Tandy s documentation they tell us that the IY register may be
165. maries are wired in series on the 120V version they are wired in parallel This allows us to specify the same parts list for both versions it s only the PCB artwork which is different TRS BU Model 1 Replacement Power Supply dean bear2gmail com 250mA FUSE Active 7 5 0 0 7 5 Volt PCB Toroidal 240 volt Neutral 6 0 0 6 volt PCB Toroidal Active 7 5 0 0 7 5 Volt PCB Toroidal PCB ARTWORK Scale up this artwork so that it fits onto a 150mm X 75mm single sided copper clad board and etch it any normal way I use the toner transfer method and etch with good old Ferric Chloride Note there are two different artworks the top one is for the 240V design and the bottom one is for the 120V design TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 26 H3vwUH BSSEUELI 4v YJHHU8g AJWON IM rmoas lismpsasad ngab 82H H3vw uH BSSEUELI v AJWON IM mos lisrmpIisasd nsab L ASSEMBLY The 7 5 0 0 7 5 transformer goes in the centre over the area which reads M1 POWER SUPPLY and the 6 0 0 6 transformer goes on the end over the area which reads 120V or 240V POWER PCB Pay attention to the polarity of the bridge and the capacitor and the LED if you are installing it it s optional but a nice touch TESTING Prior to plugging it into a TRS 80 look for the correct voltages on the output connector which is around 15 17V
166. mes CHECKNUM CP O JR C KEYIN2 The new name for KEYIN CP 9 1 Anything bigger than a 9 JR NC KEYIN2 PUSH AF etc This will allow input from the keyboard and only accept the O0 to 9 digits If you want to use plus minus and decimal points then you re reading the wrong chapter Having got them in though they are still just characters and we have to do some nifty footwork to turn them into a useful numeric quantity What we shall do is to start with zero and work from left to right through the string of digits multiplying the value we already have by ten and then adding the number represented by the digit to our value As the final answer could end up bigger than 255 we shall have to use the HL register pair remember they can do adds for most of this operation Let s address ourselves to the problem of multiplying the contents of HL by ten Doubling HL is easy as we have the instruction ADD HL HL and if we did it again we would have four times If only we had saved the first value we could add that to get five times and then double it again for ten Well the DE registers have been lazing about doing nothing let s use them TIMESTEN PUSH HL POP DE DE has original HL value ADD HL HL HL is now doubled ADD HL HL HL is now four times ADD HL DE HL is now five times ADD HL HL HL is now ten times Just hold it a minute HL is doing sums DE is helping B knows how many digits to process who s left to tell us whe
167. mes very attractive ta add memory la your Medel 1 The chips will bring your System up bo the full 48K elf RAM il ia capable of running Keep in har the bottom 16 is resmrved for which holds BASIC operating systems etc One of the advantages of using the 4764 is thal if requires much less power cooler oparaban In fact the redug tion is dramatic Before making the mod fication the power supply pass transistor goi wary hal Now runs so coo that it is hard to detect imal it is actually operating 200 Idaho St Silver City NM 8806 FHaute B Hox 2862 Silver City NM ag Say You Saw 1 in CO TRS BIT Another in The modification is that it cuts down on reboots Iram memory errors The is a lot less chance l glitches with only B memory chips versis 24 And mosi important the modification gliminates ihe memory problems so com with the interface unite This gar true ol the earlier internace models although the memory probem exist with the newer inbartacass We were lucky anough 1a obiain some factory rejecta ol interface boards and almost invariably ihe problema wilh the boards were memory problems By irr Stalling the 4164 dynamic chips on Ihe computer board mamay errors comman bo using Ehe in igrface vanished 4164 Variations Watch Qut This pin numbering an Ihe 41645 is dif ferent irom the existing RAMS used
168. my Model I won t plug into my Model 4 is this right A Yes that is right the cassette cable supplied to Model I computers has a black hard plastic boss on it with a thick plastic ring It fits into the Model I Tape plug but it won t fit in anything else You need to buy the later type cassette cable which has the thin metal ring protruding from the black flexible plastic boss Tandy sold the Model I cassette cable up until about 1980 so all cassette cables made after that time is the one you want ianm trs 80 com GENIE OWNERS LOAD AND EVEN COPY SYSTEM TAPES ONTO YOUR SECOND CASSETTE WITH TH SYSTEM LOADER Though it is possible to both load and save Basic programs onto Genie s internal and external cassette systems the inherent fault is that machine language programs can only be loaded via the internal cassette which sometimes is not so reliable Mike Chalk has altered all that For with his System Loader not only can you actually load machine language program through the second cassette port but can even copy them as well Yes you can actually make copies of system tapes and have the choice of either the second or internal cassette to do it It s all made very easy too just by pressing a single key with no need for a file name Still more goodies in the program for Mike has devised it so that it prints out the name the entry start and end addresses in the bargain And there s a facility to jump to any address during the pr
169. n Belgium and proudly built and shipped from Australia Kit form or fully assembled Order yours today http ianmav customer netspace net au trs80 emulator TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 20 0013H Device Input Usually used for 1 byte read from disc file LD DE File control block of open file CALL 13H Byte returned in A Zero flag set if no error JP NZ Disc error routine 001BH Device Output Similar to above for 1 byte to disc Character in A register LD DE File control block CALL 1BH JP NZ Disc error routine 002BH Keyboard scan Scans keyboard and returns character in A Very similar to Inkeys from Basic Uses DE and IY registers char in A reg and Zero set if key pressed Does not hang around waiting usually used with a loop KBSCAN PUSH DE PUSH IY CALL 2BH POP POP DE OR A JR Z KBSCAN RET character in A 0033H Video Ouput Outputs character in A to current cursor pos Uses DE amp TY character in A DISPLAY PUSH DE PUSH IY CALL 33H POP IY POP DE RET 003BH Printer Output Exactly the same as for video but this routine will hang up if printer not connected On Model 3 the hang up can be broken with Break 0040H Line Input Keyboard line input terminated with Entry Entry HL points to your buffer B No bytes Exit HL buffer and B No of characters Uses DE register 0049H Key Input Similar to Keyscan but waits for key stroke TRSSBIT VOLUME 27 ISSUE
170. nd 11 000 hours MTBF mean time between failures In case you don t have a calculator handy that works out to about 458 days continuous use Since most people used the drive about 8 hours a day 5 days a week 8 5 260 10 400 this is how Tandon arrives at an approximate 5 year lifespan 5 years being 260 weeks Beyond that the drive is living on borrowed time The drives were super expensive when new and hence usually had a hard life often used for more than 8 hours a day and in certain cases like a database for a BBS run continuously Long story short they are very often worn out by the time I get them and often need replacement due to stiction google it platter surface breakdown bad blocks or just plain worn out The solution will be to replace it THOSE THREE WIRES Pretty soon after pulling apart a TRS 80 hard drive you notice three wires connected to various points on the hard drive logic board If you have worked on old XT and 286 PCs which have MFM drives you know you don t have these three wires to worry about Tandy complicates things because once the three wires have been removed from the MFM logic board the drive will refuse to format crashing out with a Write Protect error So what is going on here Once I explain what these wires do it becomes much clearer TRSSBIT VOLUME 27 ISSUE 62 JUNE 2013 PAGE 21 ORANGE WIRE The orange wire connects up with the protect switch on the fron
171. nd 6 heads if you specify 406 cylinders and one partition per head yes you end up with 6 partitions but lose 20Mb of disk capacity The way to make full use of the disk capacity is to specify fewer cylinders and spread them across all 6 heads So when RSHARD asks for how many cylinders for the partition instead of replying 820 we would say 136 and when RSHARD asks how many heads for the partition instead of replying 1 we would say 6 That way you send up with your partitions spanning cylinders 0 135 for partition 1 cylinders 136 271 for partition 2 and so on Once you decide on how your partitioning will be you need to record it because if you lose or ruin the HD Boot disk it can be a real nightmare to remember where all the partitions start and finish THEN MANIPULATE YOUR HARD DRIVES The driver is invoked via the command SYSTEM DRIVE x DISABLE DRIVER RSHARDn lt Enter gt Where x is the TRS BBIT VOLUME 27 ISSUE 1 MARCH 2013 PAGE 28 volume number is the version 5 for Model III LDOS 5 3 1 or 6 for Model 4 LS DOS 6 3 1 See examples 1 and 2 Formatting the hard drive is accomplished by using the command RSFORMn x lt Enter gt Again n is the version and x is the volume number Once the first partition is formatted you can copy the DOS to partition 1 and make it the system partition thusly BACKUP 0 x NEW S I QzN Enter and change the system drive so the hard drive is now drive zero SYSTEM SYSTE
172. nely if not ex on If you print lot we recommend the pint there is a saving All bottles have a to strong heat or sunlight 10 How to re ink color cartridges We have color cartridges or uninked cartridges for the most popular printers You can use your MAC INKER to color an uninked cartridge or to re ink a colored cartridge in its original color You require a Colored Ink Kit which includes an inking element and a bottle of ink of the color chosen With gold and silver color you can re ink a color cartridge but not ink an uninked ribbon in gold and silver We have now available Multicolored MAC INKER ba for multicolor ribbons 2 3 and 4 bands In this case you require the MAC INKER the appropriate multicolor adaptor and one bottle of ink per each of the of your ribbon 11 Any concluding thoughts The first MAC INKER was sold in May 1982 As we go constantly improved and our products using new designs techniques and materials E which have become available in this apparently humble but useful nne hp 2 we could never imagine that we would be able to develop a MULTICOLORED RIBBON re inking technique We have no 88 we have over 100 000 units in the field We have association with the Apple Macintosh whatsoever In fact we called our product MAC INKER long before the Macintosh in the hope to be able to write one day OVER 50 000 SOLD We are grateful to our Customers who have made it possible to reach and exceed th
173. ng these right back from the original Arcade Invaders and feels he wants a rest The reason being that he has always bettered his preceeding program and feels that with Firebird he has reached a pinnacle Many programmers of many machines have tried to emulate the arcade game Firebird but nobody the Americans included have managed to get the circling swooping firebirds on a computer Until now alterations needed recommend doing it That updating when the Model change computers will be kept to a For TANDY TRS 80 amp VIDEO It is incredible how the Firebirds peel away circle around in numerous positions on the screen then suddenly sweep in to attack all the while raining down their Even if yo u manage tt dodge all their bombs whilst shooting them down it is as though they realise they will not get you this way for without warning they ll take kamikazi action and come straight for you Then come the Astro Blasters shooting down a solid energy bolt to fry you completely in adition to their own brand of super bomb Oh you can fire at them but a solitary hit will have no effect whatsoever on these nasties As though Firebirds and Astro Blasters are not enough as the game progresses come the Megon Bombs With no less than three hits needed to destruct And you can t dodge hem easily either as their explosions spread Scores are kept of course and there is the now expected realistic sound effe
174. nges to your source file so that after assembling it looks like this TRSSBIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 17 1 ORG 7800H 2 LOAD 7800H 3 7800 C5 PUSH BC 4 7801 21003C LD HL 15360 5 7804 010004 LD BC 1024 6 7807 36A1 LOOP LD HL 161 7 7809 23 INC HL 8 780A OB DEC BC 9 7808 78 LD A B 10 780C B1 OR C 11 780D 20F8 JR NZ LOOP 12 780F C1 POP BC 13 7810 C9 RET 14 END If you haven t got a printer write down the object code bytes C5 21 00 3C etc as we are now going to change the ORG to another value say 8700H and re assemble Comparing the object code generated for the two addresses should show no difference This is VERY IMPORTANT It means that our program unlike most m c ones will function correctly anywhere in memory We are not tied down to a particular block of Ram that might be needed for something else Now as for linking it with Basic we have a number of different techniques available but all of them require us to know the individual values of our code in decimal rather than hex If you are using E m M 80 or one of the other very powerful assemblers then you will have no doubt large reference tables in the manuals to help with the conversion process That s not how we do it with Zen however simply get back to Basic and the TRS80 will do it for you To get to Basic from cassette or Aculab do a Jump or Goto memory address 114 from disc Zen return to Dos first and then Basic Having got t
175. nochrome Z280 world or the me too plain PC compatible zone tried to really make a really stunning classy TRS 80 ianmGtrs 80 com TRSSBIT VOLUME 27 ISSUE 02 JUNE 29013 PAGE 32 EM ULTRA PERFORMANCE MS DOS SYST 0 Introducing the Tandy TRS 8 Model 2000 Personal Computi ly 2000 HD L 2 Disk Tandy 2000 Hard Disk Tand 4450 695 Men Non interface monitor color graphics and Digi Mouse not incl ity Dramatic Speed and Increased Storage Capat Let You Perform Bigger Tasks in Less Time m User Expandable for Your Future Needs W m Choose From the Hottest Names in Software m Stylish Ergonomic Design Gives You Maxim Versatility Productivity and Comfort a The Setting New Standards for Personal Compt ers you ut Tandy 2000 is a truly remarkable computer that sed Sr wi ng much more than other 16 bit MS DOS ba pansion Qe puters More speed More disk storage More id goa 22 Advanced graphics And the superior quality ar that keeps Tandy Corporati n at the forefrc zz Industry Satake KE Large Library of Proven Software Rapidly be i dusfry standard MS DOS 18 5 Bring you popular and sophistical d programs onr t c ket Programs like dBase II Microsoft v wo PFS File MuliMate and many more under development including the state MS Windows cperating 275 Extremely High Speed A Aek ES UE au EIER
176. o gt Ready prompt key the following to extract from memory the decimal values of the program that Zen loaded into memory on the last assembling operation AD 30720 FOR X 0 TO 16 PRINT PEEK AD X NEXT and you should get 197 33 0 60 10 4 54 161 35 11 120 177 32 248 193 201 This is obviously some very important data so lets turn it into Data statements TRSSBIT VOLUME 027 ISSUE 2 JUNE 29013 PAGE 18 60 DATA 197 33 0 60 1 0 4 54 161 70 DATA 35 11 120 177 32 248 193 201 If you haven t forgotten we discovered earlier that Basic stores integers in memory with each one being allocated two bytes Well since we have seventeen bytes to put somewhere lets reserve some memory for 9 integers by setting up an array US 8 US for USR makes it integers and subscripts 0 to 8 give nine values i e eighteen bytes of Ram so 10 DIM US 8 OK we ve got 18 bytes where is it Well the problem is that it is likely to move about depending on whether or not any other simple variables come asking Basic for storage space But wherever it is Basic will always give us its position via VARPTR and simply asking for VARPTR US 0 will point to the first byte of the 18 To put the decimal values back into memory we simply execute with Pokes something similar to the Peeks that got them out 10 DIM US 8 20 FOR 0 TO 16 30 READ 40 POKE VARPTR US 0 X 50 NEXT X 60 DATA 197 33 0 60 1 0 4 54 161 7
177. o display them on the video as that isn t automatic either We must consider carefully just which keys on the keyboard we are prepared to recognise As apart from the normal visible characters from a space value 20H all the way through the numbers 30H to 39H and the alphabet both upper and lower case there are the arrow keys penny plain and two pence shifted If we don t set our thoughts out carefully at the beginning our programming will have some unpredictable effects This Basic program will demonstrate the decimal value returned by these keys 10 5 INKEYS 20 IF X THEN 10 30 PRINT ASC X 40 GOTO 10 58 VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 8 With the exception of the up arrow by itself which returns value of 91 as it is a displayable up arrow character all of the others including lt Clear gt and the big white one give values less than 32 These are known as the various control codes for the output devices such as the video or a printer and do weird things like clearing the screen or throwing a page or blanking out a line etc Handling all of that first time is just too much so to keep things relatively simple we shall restrict our input so that it recognises just the back arrow value 8 as a backspace delete and the Enter key as the end of input As we want to retain the input assume it s the name of the person who is playing our Vacuum Deserters game we need to allocate some m
178. o make that 16x 4164 Ram chips Your motherboard will need a PAL chip installed at U72 so contact me if you need one or any instructions on how to upgrade the Model 4 to a 64K disk system 2 Q imported a Model 4 from the USA and it has a B amp W CRT not a green one It s got screen burn and I want to change it how do I change the CRT A The first few production runs of Model 4 computers for the US domestic market came with B amp W CRTs so this is normal The rest of the world got green CRTs from the get go You can easily replace the CRT if you watch and follow all the steps in my YouTube video http youtu be 9SMXSMSSCZU Finding replacement tubes can be difficult to find I sell them but if you are looking for them from electronics parts supply firms in your locale the green tube carries the part number 12VCMP31 and the B amp W tube is part number 12VCMP4 3 Q My Model 4 RS232 serial board doesn t work can I use one from a Model III A Yes you can use a serial board from a Model III they are interchangeable If you have one of those Model IIIs or 4s sold without a serial board you can install one from any Model III or 4 computer or any serial board listed in eBay for a Model III on a Model 4 and vice versa 4 Q Where are the brightness and contrast controls on a Model 4 A Under the left hand side of the computer TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 42 5 Q The cassette cable from
179. o refer only to the original fundamental commands which to a great degree are all upwardly compatible Zen in its original cassette only form is marketed by Newbear for the TRS80 and other Z80 machines Sharp Nascom etc and in its upgraded enhanced format for the TRS80 Cassette Aculab or Disc by Laurie Shields Software Just to get started and at the same time to use Zen to explore the inside of the TRS80 key the following Q5712 lt E gt and also by itself X lt E gt Now we have some explaining to do as your video looks like a meaningless jumble of numbers and letters It actually is displaying part of the Level2 Rom a few other bits as well and should be 1650 C5 4E 44 C6 52 D2 45 ENDFORRE ND OR E 1658 53 45 54 D3 45 54 C3 4C SETSETCL SET ET L 1660 53 4D 44 D2 41 4E 44 SCMDRAND S MD AND 1668 AF 4D CE 45 58 54 C4 41 OMNEXTDA OM EXT A 1670 54 41 C9 4E 50 55 54 CA TAINPUTD TA NPUT 1678 49 4D D2 45 41 44 45 IMREADLE IM EAD E 1680 54 C7 4F 54 4F D2 55 4E TGOTORUN T OTO UN 1688 C9 46 D2 45 53 54 52 IFRESTOR F ESTOR HL DE BC AF RI IX IY SP PC 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 5514 402D If the numbers you have on display for the last two lines are a bit different DON T PANIC It only means that you re on cassette or floppy tape or are using a different Dos from the one I was using when this was written In order to understand any of what Zen is trying to tell us we must first
180. ocedure It s a Basic program which can therefore be loaded from any source and it creates a machine language program to do the work It s even useful for the TRS 80 too It s from Kansas and only from Kansas 8 50 DISASSEMBLER This program is the ideal introduction to machine language for it allows you to list system tapes and even the resident Microsoft Basic in ROM allowing the start and stop addresses to be specified with each line displayed slowly and a facility to halt the display There is the option to either disassemble parts or whole machine language programs from memory or strings of machine code can be types which will be translated into standard assembly language It s another from Mike Chalk so has a bonus of allowing conversion of hexadecimal to decimal and decimal to hexadecimal Suitable for both the Genie and Tandy TRS 80 and only from Kansas 8 50 All prices VAT paid and post free First class return post service Barclay card Visa orders dispatched same day if phoned in by 3pm Answering machine ordering service after 6pm and Sundays to allow use of cheap rate Catalogue available on request Kansas City Systems Unit 3 Sutton Springs Wood Chesterfield Derbys Tel 0246 850357 TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 43 Goodbye hard drive Hello FreHD By Garry Howarth Sydney NSW After 25 years of trouble free service my faithful old Toshiba hard drive finally went out in
181. oi to clean out Ihe pin holes A small prod was used to lift the two pins from the board so we could get at them You could get another 741502 and mount it pig gyback and then wire it for 5 volts and ground rather than unsolder the existing pins but that is up to you Next connect pins 8 and 9 together and connect them to Z38 9 address line 15 Last con nect a signal diode such as a 1N4148 with the cathode bar to pin 10 of 737 The anode end arrow is connected to pin 10 of Z74 That completes the modifications There are no other modifications required to complete the project Some Conclusions It is important to keep in mind that the first 16K of memory is reserved by the ROMs in the TRS 80 Model I We under stand that there are other operating systems available in ROM but presently we have no further information In the photograph of the unit shown here the ROMs used are a special program dedicated to various amateur radio func tions such as ATTY code copying slow scan etc But that is another story that may never be written 1 he system is always in a state of flux One last item Those people who have interfaces with memory in them must remove the memory chips in the inter face This prevents memory contention between the two sets o memory We have modified three computers so far The first took severai hours of study and work The last one took about two hours 10 modify using this article as a gui
182. omputing Pages 76 amp 77 Assembled with Z80asm on Debian 7 z80asm 1 i babyroot asm Larry Kraemer H501 H502 ORG 5000H LD HL 3CO00H LD DE 3C01H LD BC 03FFH LD HL 20H LDIR LD IX 5090H LD A 3FFEH OAH LD 3FFEH A LD SP IX LD B 7FH Is INC SP DJNZ H501D LD HL 6001H XOR A Eb JOH A LD QA 6 PUSH AF LD A C LD HL A INC HL LD 3C22H HL LD A H Change this for RAM Size xxK CP OOH 780 CO 00 JR 7 5062 16K 32K 48K PUSH HL 4000 4000 4000 8000 4000 000 PUSH IX POP HL CP JR Z H5062 POP HL POP AF TRS BIT VOLUME 97 ISSUE 4 DECEMBER 22013 PAGE 52 LD HL A DEC HL DEC HL ED HEPRSAR LD B A LD A HL CP B JR Z H5049 LD D 1BH 20 TO WATCH IT WORK PUSH DE JR 5064 H5049 INC HI INC HI LD A HL CP B JR Z H5054 LD D 10H PUSH DE JR H5064 H5054 DEC HL INC HL INC C LD A HL LD B A CP 00H JR NZ H5026 INC HL LD C 00H JR H5026 H5062 JR H50C8 H5064 LD A H AND OFOH RRCA RRCA RRCA RRCA LD D 22H JR 5091 LD A H AND OFH LD D 1BH JR H5091 LD AND OFOH RRCA RRCA RRCA TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 53 RRCA LD D 10H JR H5091 LD A L AND OFH LD D 09H JR H5091 POP
183. one desiring to make This change has long since voided the warranty by open ing his or har computar to make changes However tha changes should be claar so that any amateur with ewen basic solder ing Knowledge can make the mods re quired Firet please obeenve ail tha usual Warnings and precautions about handling ine 41645 They are sensitive to salit mechiciiy and can be ruined through handling After removing ihe computer carefully remove the existing RAMs 213 through 220 They all in a line boget September 1983 CO 48 PAGE 32 er on the top row just below the large power supply pass transistor Next care fully bend pins and 9 on each of the new chips to slightly more than 90 degrees enough so that you will be able to wtre wrap the pins If your 41645 have the pin connected as mentioned above you will need to lift these pins also Now care fully insert all the RAMS into the sockets making sure that al pins make good connections into the sockets Pin on the new RAMs requires 5 volts so these pins should be wire wrapped daisy chained and then connected to the 5 volt bus In order to reduce noise pick up both ends of the line were connected to 5 volt points Z20 pin 8 is connected to 239 pin 16 5 volt point and 213 pin 8 is 5 BIG Model II 64K 3395 in stock Call for 26 4160 1 Drive 1014 00 26 4161 2 Dri
184. ough to operate and comes complete with a teaching programme to show you how Your Genie is reliable too manufactured to the most stringent standards with top quality components And even in the unlikely event that your Cenie should ever temporarily fail to please you are assured of very fast competent service because the Genie III is only available from our specially selected SUPERDEALERS Dealers whose technical expertise and experience in the fields of installation software availability and repair is proven Finally it s compatibility with CP M or Level II BASIC means there is more Software available for Genie III than any other comparable system Please send me FREE 16 page colour brochure on the 1 Genie Computer System I enclose 25 postage CT 82 Piper egg Road Derbpakire DE4 BLE Telephone 0629 4995 i Telex 377482 Lowlec G TRS BIT VOLUME 07 ISSUE 2 JUNE 2013 Chapter 5 Now that it works lets change it But first we will review what we have learnt 1 The registers A B C H L etc or the register pairs HL BC etc can be loaded with a value using the LD instruction LD BC 1024 2 The contents of the registers can be incremented or decremented INC HL 3 Data can be transferred between the registers again using the LD Instruction LD A B 4 The contents of the A register can be compared with some other value CP 8 and if they are the same the Zero
185. parisons between this series and that of Scott Adams so we will leave it to them to make their judgements The only comment that we will make at this time is that we find it quite invigorating to play an Adventure game by a different author as obviously they construct their stories slightly differently Mysterious Adventure 1 The Golden Baton is available on cassette for TRS 80 or Video Genie machines of 16K or more and on disk for 32K up machines It occupies a full 16K The tape versions save their game to tape and the disk to disk Tape version Disk version 11 00 Both prices plus VAT and 75p P amp P TRS 80 amp VIDEO GENIE SOFTWARE CATALOGUE 1 00 refundable plus 50p postage A J HARDING CMOLIMERX MOLIMERX LTD 1 BUCKHURST ROAD amp 28 COLLINGTON AVENUE BEXHILL ON SEA EAST SUSSEX TEL 0424 220391 TELEX 86736 SOTEX G TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 32 5 WELCOME TO THE 28135 XMAS EDITION DEE AND I WISH YOU ALL A VERY MERRY CHRISTMAS AND A HAPPY NEW YEAR THANK YOU ALL FOR YOUR HELP SUPPORT CONTRIBUTIONS AND ENCOURAGEMENT THROUGHOUT THE YEAR SPECIAL THANKS GO TO DOWN THERE IN OZ FOR ALL HIS CONTRIBUTIONS OVER THE YEAR THEY ARE WRITTEN IN SUCH A PROFESSIONAL MANNER AND SHOW SUCH KEEN INTEREST AND ENTHUSIASM FOR ALL THINGS TANDY I JUST CAN T WAIT UNTIL THE NEXT ISSUE TO SEE WHAT HE S COME UP WITH THANKS ALSO TO THOSE OF YOU WHO CONT
186. port that it gets anybody up to any sort of standard after it has been assimilated the reader should have sufficient knowledge of flying and the theory of flight to fly in the program itself The second feature of assistance to the novice pilot is a feature in the program which enables the user to practice landings When the program is started if one presses the P key the aircraft is automatically put 11 miles out from London Airport approaching on an instrument landing The controls are pretty well complete even to dive and wheel brakes The flying track may be continuously monitored on the map display Bearing and distance to your intended point of landing are available all the time The instruments incidentally consist of Artificial horizon Attitude Fuel Aeleron indicators Compass Elapsed time Indicated airspeed Turn indicator Distance to landing Power setting Flap indicator Rate of climb Elevators Altimeter Six maps may be chosen as follows Scotland Northern England Southern England Ireland Eastern U S A The whole of the U K Route information and present position are shown on the map displayed It is very difficult to think of any factor that the authors have overlooked Even the quite meaningful thinning of the air with increasing height which greatly affects the airspeed indicator in real life is taken into consideration Rather than having a fixed stalling speed this continuously changes with the flight configuration the weight
187. purchased on eBay for about 15 but be sure to request a warranty of some sort as many have date codes going back to the mid 70s and are pulls meaning they are 2nd hand and removed from used office equipment not in itself a bad thing if the parts are OK Despite being electronically fragile the UART is easy to TRS BIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 3 replace because its in a socket so if you have spares on hand it can be changed in around 10 seconds The line drivers however are soldered to the board WHY ARE LINE DRIVERS PRESENT A line driver is an amplifier used to improve the strength of an analogue or digital signal at its source by driving the input to the transmission line with a higher than normal Signal level This increases the quality of a transmission over a long run of cable and is especially important for RS232 cables more than a few metres long Basically they give the signals going out of the RS232 port a bit of extra oomph so without that function there may be no result in the lookback test even though the BRG and UART are functioning correctly On the Model I RS232 board they are U3 and U4 which are MC1489 chips and U12 which is a MC1488 chip Since they are soldered in if you suspect one is causing a problem unsolder and replace all three they are easy to find and inexpensive COMPATIBLE DEVICES What do you do if you can t find a TR1602 for your Model I RS232 board Luckily t
188. rare 48K disk based machine with the optional factory high resolution graphics kit cat no 26 1125 installed For those who can t remember the graphics option was super expensive 549 in 1982 and not many people bought it because there was no software support for it The few computers which have the graphics option fitted are considered to be priceless restore at all costs relics so to me this one was a must fix Checking with Ivan I found that this computer was owned by Graham Read and had not been in service since 1995 First I thought I would deal with the easy machine the 16K and had a look inside to find it surprisingly clean Nothing looked out of place so I plugged it in and was soon greeted with the familiar Cass prompt and flashing block cursor The picture was shaky but the machine seemed to work quite well despite a few unresponsive keys made a list of the non responsive keys and powered the machine down Shaky picture on this type of computer is usually the result of ineffective ripple current filtering in the power supply and it didn t take long for me to find the culprit a bulging electrolytic capacitor replaced it as well as the line filter caps re installed it in the computer and was pleased to see a rock solid picture After fixing the keys I tested the machine further by loading some software the old fashioned way off cassette and was pretty pleased with my work The computer had been stor
189. re the buffer is with the characters in it Time to use IX or IY I suppose and since we ve been pushing and popping IY like there was no tomorrow we ll use that one Assume IY points to our string of digits this is what you do Get the character pointed to by IY into the A register Subtract the 30H from it so that we re left with just 0 to 9 Add it to HL no that isn t allowed TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 14 The BEST in TRS 80s Call The Right Stuff Ask for Ian The number is 61 416 184 893 That s The Right Stuff And he s in Melbourne http ianmav customer netspace net au trs80 TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 15 Add L to A load L with A if Carry then increment That is all just too messy Try it this way Load the E register with A make sure D equals zero Add DE to HL much tidier The only point to watch is that IY never expects to be pointing in the right direction and always thinks that you re going to want the one just to the left or half a dozen to the right like this IY 1 or IY 6 If we really do want the memory address that IY is actually pointing to then we must use so the next bit LD A IY 0 SUB 30H LD E A LD D 0 ADD HL DE INC IY again for the next digit so DJNZ TIMESTEN This will cause a monumental disaster if for some reason the user had just pressed Enter instead of inputting some numbers as B wou
190. results ina fairly high current and I needed to use 74LS06 to drive the output Signals Also many level translation chips especially bi directional ones would not work with such low resistance pull up values Fortunately I found I was able to avoid level translation chips in my design While I could have used a 74LS05 for the input signals I found it was simpler to use a 74LS06 for both input and output so I could chose the IC that was most convenient Originally I put a level translation between the Pi and the 741506 for the output signals but it turned out not to be necessary and the Pi seems to be able to drive the 74LS06 directly The input signals use the open collector of the 74LS06 could be a 74LS05 but easier to use the same IC for both and rely on the pull up resistors on the GPIO pins to perform the level translation to the correct voltage The Pi has programmable pull up resistors on the GPIO pins so I just program them in the initialization code Two GPIO pins also have pull up resistors on the board itself so it s convenient to use these two as input pins for the floppy drive interface Note all Raspberry Pi pins refer to the Rev 2 pins Current configuration is shown below Read Data must be connected to GPIO pin 10 Write Data must be connected to GPIO pin 9 GPIO pin 11 which is the SPI clock should be left alone I connect it to a pin for use with a logic analyzer to help me see what s happening TRS B
191. rocessor user and for dates Superbrain SD or QD or any compatible system of our word processing workshops return the Apple under DOS3 3 or CP M Tandy TRS 80 coupon or ring Mike Cooper on 0458 45359 Model I or III North Star Horizon Comart or Ohio Scientific C2 or C3 series 4 We ll have links to other systems ready by the WO rd sm ith S time you read this advert ring for details We have special software support for WordStar compu ers Spellbinder Scripsit and Applewriter so even tricky jobs such as directories technical IH ty publications tables and foreign languages problem for your word processor and Anvil If you re not sure how to do it come to one of our ee word processing workshops and see how we can Company help you to produce anything from a price list to a batch of bar code labels And since we re in central Somerset rather than on the Central Line we might even offer you some cyder and a byte to eat as Address Tel No West End Street Somerset BA16 0LO wor d sm iths 0458 45359 Telex 46401 TRSSBIT VOLUME Q7 ISSUE 3 SEPTEMBER 2013 PAGE ell From Altronics 1 7 5 7 5 PCB A30 00 Each 30VA Toroidal Transformer Center Tap 1 6 0v 6 0V PCB A30 00 Each 30VA Toroidal Transformer Center Tap 1 1K Resistor A0 80 Each 1 LED A0 21 Each l 1000uF 35V A2 00 Each Electrolyti
192. rs adding a hard drive to a Model I is no more difficult than adding one to a Model III or 4 NEXT TIME FreHD and how to build it ianmQGtrs 80 com TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 28 REFERENCES 1 In Mav s Workshop TRS8Bit Vol 7 No 2 June 2013 pp 21 26 2 http ianmav customer netspace net au trs80 emulator 3 Model I HD Adapter pdf 4 A Really Hard Model I Computer News 80 Vol 4 No 5 7 10 Mavric is IT Specialist who also restores and collects TRS 80 s and classic cars He live with his wife and kids in Melbourne Australia TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 29 5 RRY E R n RY M R RY ERRYAM MER M M Ab ZG GG p ZG gt TL gt P P Dp 15 D PDP D D AS RYXMASM AMASMERRY AMASMERRY XMAS TRSSBIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 30 199 119 120 130 140 159 160 179 189 190 299 219 220 230 240 250 260 279 280 290 399 319 329 339 CLEARSOS MS MERRY XMASMERRY XMASMERRY XMASMERRY XMASMERRY XMASMERRY XMAS GOSUB 220 READ S IF S 8 GOSUB 160 READ L TS MIDSC MS5S5L X PEEK CVARPTRCP 1 PEEKCVARPTRCP 2 256 REM THIS AND THE NEXT LINE ARE NOT NEEDED ON 16 OR 4K SYSTEMS IF X gt 32767 THEN X X 65536 FOR Y 1TOL POKE X S yY sASCC MIDSCTS 5Y51 NEXT Y GOTO 59 LPRINT P GOSUB220 READ S IFSZOTHENLPRINTPSt READS IF S299 TH
193. rs80 2 TRS 80 Catalog RSC 5 Sept 1981 pp 13 3 http www classic computers org nz blog 2011 10 29 trs80 modell rs232 htm 4 Model 4 4P Technical Reference Manual Tandy Corp Cat No 26 2119 1985 pp 142 3 4 2 16 RS 232 C Circuit EARLY RS232 WITH BR2941 AND R1 R11 AND C9 2 lt 3 oc LATE RS232 WITH BR1941 AND NO RIO R11 C9 erie1 i deers In FIFI IIS initis tin 002151925 251800 I tell WOOS TINS uA cA TRSSBIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 7 MODEL BRG INSTALLED IN 1 RS238 BOARD NOTICE PIN 18 AWAY FROM THE SOCKET Mavric is an IT Specialist who also restores and collects TRS 80 s and classic cars He live with his wife and kids in Melbourne Australia Starquest by Automated Simulations Rescue at Rigel 16k Lil 12 96 32k post lt n Star Warrior na dme Graphic adventure in h Please make cheques PO s payable to Algray Send to Algray Algray House 33 Bradbury S Barnsley South Yorkshire S708AQ All prices inclusive of VAT Post amp Packing Tek Barnsley 0226 83199 TRS BIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 8 WL Durpueg 1uejed sn YSN ut 0 ZVS 008 1 T10 6265 9 06 iO 65566 1622 929 09 62216 pueniog Hed eouetos MN 06201
194. rt displaying the 3 K 4 If it s a CR then ST It should be obvious by register pair to point getting the character p program looks like this Ssage i e the address in Ram of rogram might also want to display the other the message and for that purpose we PRESS ENTER followed by CR characters on the video on OP displaying and return into by one eep checking on whether or not a CR has been displayed now that what we want is to set up a to the message and go round a loop ointed at displaying it checking for a CR and if not incrementing the pointer and looping back The 1 ORG 7800H 2 LOAD 7000H 3 CR EQU 13 4 7800 210778 LD HL MESSAGE 5 7803 CD1378 CALL VIDEOUT 6 7806 00 NOP For Breakpoint 7 7807 50524553 MESSAGE DB PRESS ENTER CR 7 780B 5320454E 7 780F 5445520D 8 7813 7E VIDEOUT LD A HL TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 16 9 7814 23 INC HL 10 7815 CD1D78 CALL OUTPUT 11 7818 FEOD CP CR 12 781A 20F7 NZ VIDEOUT 13 781C C9 RET 14 781D D5 OUTPUT PUSH DE 15 781E FDES PUSH IY 16 7820 CD3300 CALL 33H 17 7823 FDE POP IY 18 7825 D1 POP DE 19 7826 C9 RET 20 END By now you should be so expert at assembling these programs that jumping to them with the breakpoint will be returned in the HL regist memory after the last cha is worth mentioning the de
195. s remain visible to both DOSes and this works because both LDOS and LS DOS share the same file structure Check my video on YouTube showing a dual boot hard drive EXAMPLE 1 Partitioning by HEAD 1 Power on Hard disk then the TRS 80 Model 4 2 Boot Model 4 with LS DOS 6 3 1 disk which has RSHARD6 DCT and RSFORM6 CMD on it 3 Configure the Hard disk by entering the SYSTEM command SYSTEM DRIVE 1 DISABLE DRIVER RSHARD6 Prompt as follows Enter drive address 1 2 and F R 1 F enter Enter the STEP RATE 10us 7 5ms 10 enter Enter the physical TRACKS per surface 306 153 Enter the total number of HEADS 4 gt 4 Enter partition s number of heads 1 4 gt 1 Enter partition s number of cylinders 153 enter 4 Format the Hard disk using the TRSFORM6 command RSFORM6 1 Prompt as follows Disk pack name HARDA Password PASSWORD Manual Lockout N 5 Repeat the process for remaining partitions SYSTEM DRIVE 2 DISABLE DRIVER RSHARD6 SYSTEM DRIVE 3 DISABLE DRIVER RSHARD6 SYSTEM DRIVE 4 DISABLE DRIVER RSHARD6 answering 1 head and 153 cylinders each time 6 Format the partitions you just created RSFORM6 2 Prompt as follows Disk pack name HARDB Password PASSWORD 58 VOLUM
196. shop com is this australias first pc html TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 48 TRS BIT VOLUME 27 ISSUE 04 DECEMBER 2013 PAGE 49 UTILITY Not mathematical this program roots out your defective memory locations Babyroot Dennis Bathory Kitsz Roxbury VT 05669 abyroot is program that exercises the TRS 80 RAMs developed this program be cause during a particularly warm and humid day my pro grams Started to crash for no ap parent reason scratched out an inelegant but workable fiet wersion and located wayward address 4A02 The program exercises all combinations of bis in three neighboring bytes simultan eous Locations are repeated ly written to and read from 10 5 sure that they are functioning The Program Prepare Babyroot as a BASIC program or use T BUG to enter the machine code and create a SYSTEM tape Load Babyroot using the SYS TEM command enter the name RAMCHK and when the pro gram has finished loading about seconds enter 20480 The program now located at 5000 hex works over the RAM irom address 6000 10 7 nex At the end of this sequence it transfers itself to 7000 hex exer cising RAM from 4000 to 6FFF hex ach complete cycle takes 12 1 2 minutes on an unmoditied TRS 40 Al the beginning of the pro gram the screen clears and Star appears in the bottom righi hand corner About live minutes later the program transfers
197. ssic computers org nz system 80 manuals tm3 page22 jpg And some other useful technical stuff http www classic computers org nz system 80 manuals technical htm Tips for beginners 1 write the program on multiple lines and only condense it when it works 2 using the emulators you can copy the code out of the emulator edit it in your favourite editor and then copy it back although I kinda like the clunky editor in the BASIC it takes me back to my youth AS RECOMMENDED BY COMPUTING TODAY THE CENTRONICS MICRO PRINTER Ask most people what they would like as their first peripheral and the chances are they will say Printer Here is an attractive electrostatic printer from the famous firm of Centronics Capable of printing in three sizes of typeface it is easily attached to d machine by way of the parallel interface The logic is fully TTL compatible and STROBE Acknowledge and Busy lines are provided to make life easy Cost of this wonderful peripheral is a mere 195 00 VAT The printer comes complete with documentation connector and cleaning paper as well as a roll of the printing paper extract from COMPUTING TODAY Ex STOCK from HENRY S i E A zam CENTRONICS Ideal for PETS TANDY NASCOM s 4 QUICK PRINTER Specification 150 lines per minute Selectable 20 40 80 columns 120 m m aluminium Finish paper unaffected by Heat Light or Humidity e Full character ASC II set Paper Feed 220 2
198. stomise partitioning so that just about any MFM hard drive up to about 70Mb can be used with the TRS 80 Rule 1 LDOS and LS DOS allow up to 8 disk volumes on a TRS 80 and each floppy drive is 1 volume So this means if you have a dual floppy drive Model III then can have up to 6 partitions on the hard drive If you have four floppys on your Model III you can have up to 4 partitions on the hard drive Rule 2 RSHARD5 6 is limited to a maximum of 406 cylinders per partition Most smaller hard drives have less than that eg Tandon TM602S 5Mb has 153 cylinders and Tandon TM503 15Mb has 306 cylinders If you upgrade the MFM hard drive to say a Seagate ST 225 20Mb or ST 251 42Mb which have 615 and 820 cylinders respectively you can see that the only way to make use of all the capacity of the hard drive is to partition it Rule 3 LDOS and LS DOS limit the number of files per logical drive to 256 Clearly even on a small 5Mb drive if set up in a single volume all 256 file slots will be filled before the all of the space is allocated By making as many partitions as possible we maximise the space used on the hard drive we can also divide the partitions into categories say Partition 1 drive 0 has the DOS Partition 2 drive 1 has Superscripsit and Visicalc Partition 3 drive 2 has games Partition 4 drive 3 has EDAS PRO DUCE etc and drives 4 5 6 and 7 are floppy drives While one can set up a hard drive w
199. t a lead from pin 9 of 220 to pin 12 of 251 We routed the wire through the large hole between 751 and the ROM socket Z34 to make the con EXIIT The Computer Store Inc TRS BIT Vern Street Products 114 West Taft Sapulpa Ok 74066 4949 South Peoria Tulsa Ok 74105 918 747 9333 VOLUME 7 ISSUE 4 DECEMBER 2813 side of the board Be sure when making any of these connections to use a mini mum of solder and heat Naturally one should check any new solder joint to make sure that it isn t shorting to any ad jacent line or connection Make a con nection between 251 pin 13 to 238 pin 11 This is address line 14 and is needed for addressing the new memory Like wise connect Z51 pin 14 to 738 pin 9 which is address line 15 it your chips require pin 1 to have 5 volts they must be wired together and connected to the 5 volt line It is proba bly a good idea to connect both ends of the string to the 5 volt line as you did with pin 8 One last modification is required It is necessary to enabie the memory loca lions above 32K by activating the signal We can do this by inverting A15 ing spare gate This modification is a lit tie trickier if we want to use the spare in verting gate thal is available to us This gate is located on Z37 pins B 9 and 10 The problem here is that pins 8 and 9 are grounded and the ground connection is under the chip We used a desoidering to
200. t panel of the hard drive when disconnected from the hard drive the controller board believes its getting no Signal equivalent of the write protect button pressed in so won t permit any data to be written to the hard drive This wire is important and can t be ignored Roy found if you solder it to a place on the HDC then you can restore its functionality On the 5Meg 26 1130 and 15Meg 26 4155W early Radio Shack drives with the big 8x300 HDC you need to solder that wire to R27 pin 6 which is the pin closest to the 8x300 CPU see Picture 1 On the later small WD1010 HDC you need to solder the orange wire to the leg of R54 closest to J10 see Picture 2 While you are at it you need to bend J1 pin 5 8x300 HDC or J6 pin 5 WD1010 HDC over so it no longer goes into the 20 way data cable to the hard drive This prevents 5VDC being sent to the hard drive and shorting it out WHITE AND YELLOW WIRES These two wires go to the Active light on the front panel so the light flashes when the head on the hard drive steps in or out They can actually be taped off and not connected if you don t want the Activity light but to my mind that s a lazy solution A much better practice is to solder them to the right places to make the light work again On the 5Meg 26 1130 and 15Meg 26 4155W early Radio Shack drives with the big 8x300 HDC you need to solder the white wire to J6 solder pad 6 and the yellow wire to J6 solder pad 26 see Picture 3
201. tely the Level 2 manual comes to our aid and informs us that the video is treated as if it were a chunk of ordinary RAM of 1024 bytes starting at 3000 Hex or 15360 Dec and finishing at 3FFF Hex 16383 Dec So our object is to write in assembler the nearest equivalent of the following BASIC program 10 FOR 15360 TO 16383 PORE X 161 NEXT Now just hold on there a little That s far too complicated for an assembler programmer to understand Can t we simplify it a little first Well we could try 10 FOR X 15360 TO 16383 20 PORE X 161 30 NEXT X 40 END That s getting better but I m afraid all this FOR NEXT business is just a little too how shall we say intricate can t we get there in singles Third time lucky 10 REM Simple BASIC 20 LET HL 15360 30 LET BC 1024 40 POKE HL 161 50 HL HL 1 60 BC BC 1 70 IF BC lt gt 0 THEN GOTO 40 80 END For those who didn t skip the earlier chapters the letters used for the variables might seem familiar they are of course the same as those used for two of the Z80 registers Before we can go much further there is one important concept that we must master and that is the complete irrelevance of line numbers in assembler programming Whereas in BASIC we have the ability to refer to line numbers in the program to change the flow of control by GOTO s and GOSUB s in assembler we must identify the particular line with a label and then refer to that lab
202. the end of the line The second routine is of course to do with keyboard input and is located at 2BH Keyboard input is somewhat different from data output in that should a key not be being pressed when we call this routine then there will not be any data This keyboard scan is therefore identical in approach to the INKEYS function available in Basic To use it we must first save the DE and IY registers then call 2BH restore the registers and test the contents of the A register to see if it contains any data It is then up to us to decide if we want to hang around repeating the operation until a key is depressed or to carry on with something else and come back to the keyboard again later he video routine the start might A typical scan the keyboard display on with our usual ORG 7800H and LOAD 7800H a look like this 1 ORG 7800H 2 LOAD 7800H 3 7800 CDOA78 GETCRAR CALL KEYSCAN 4 7803 B7 OR A 5 7804 28FA JR Z GETCHAR 6 7806 CD1478 CALL OUTPUT 7 7809 00 NOP Just to give a breakpoint 8 Rest of Program 9 780A D5 KEYSCAN PUSH DE 10 780B FDE5 PUSH IY 11 780D CD2BO00 CALL 2BH 12 7810 FDEI Y T3 7812 D POP DE 14 7813 C9 RET 15 7814 D5 OUTPUT PUSH DE 16 7815 FDE5 PUSH IY IY TOIT 009300 CALL 33H 18 781A FDE POP IY 1 9 Di POP DE 20 781D C9 RET 21 END Test this routine as we did
203. the first written testimonial we ever received December 82 written by Father Mick Burns 701 S Walcott Casper Wyoming rare experience indeed exists when a product is as cost effective as yours have always been leery of testimonials making claims If one had been presented accurately representing your product simply would not have read it Some brief calculations quickly showed full payback on the very first day s use of my now treasured MAC INKER Let me sincerely thank you for such fine product Among our recent customers the FAA Federal Aviation Administration is using a multicolor red black Macinker in each of their field offices Texas Instruments has reported to us in writing net savings of 34 000 year using our Maclnkers Schools Colleges Universities Radio TV Stations Banks Army Navy and Air Force are among our constant and repeated customers Several customers have reported to us having rs best idea awards by their employer after having proven to their company the savings made possible by Now to some often asked questions 1 How many times can a fabric ribbon be re inked is a function of the length of the ribbon A 20 yard ri Epson 80 series can be re inked 60 100 times before it shows signs of wear We run a 2 yards loop Epson 80 cartridge and re inked it until the ribbon had worn out By extrapolating results the ribbon had outlasted the manufacturer s expected life of the pr
204. the others by Jumping or Going to 7800H and setting the breakpoint at 7809H What should happen is that the TRS 80 will appear to go into suspended animation until a key is depressed whence the character corresponding to the keystroke will be displayed and then control returns to Zen from the breakpoint Let s look at TRSBBIT VOLUME 27 ISSUE 03 SEPTEMBER 2013 PAGE 12 the program in more detail Line 3 This is a call have not saved any registers so should ther to our subroutine KEYSCAN Note we have been anything important in A or F then we have lost it Lines 9 to 14 This is the subroutine KEYSCAN First the DE and IY registers are pushed onto the stack and the ROM keyboard scan is called If executing the character wil a key is be in the A register state of the flags in the f The rou tine returns Line 4 a zero which means no key depression the Flag register to the contents The quickest and easiest method is simply tsel is it necessary to trigger of the Accumulator to OR the A register with i otherwise lag regist it w pressed whilst 2BH is ill contain a zero The r are not meaningful TY and DE registers are popped off the stack and then the We must now check on whether the A register contains E as If or non zero To do this A is zero then the 7 zero flag will be set
205. tian Odyessy 16k Lii 8 95 Oceans climb explore in your quest to find ater temples the fabled City of Atlantis Are you fed up with M up and grab your hard won treasures well now you get the chance tq fight back at various inhabitants of this 3 level the dungeon Send to Algray Algray House 33 Bradbury Street Barnsley South Yorkshire S70 6AQ TRS BIT VOLUME Q7 ISSUE 82 JUNE 2013 Deadly Dungeon 16k 8 96 ES Tek Barnsley 0226 83199 prices inclusive of VAT Post amp Packing Star Warrior 16k LII 15 86 32k TRSDOS 17 96 In this real time graphic adventure onto the Planet Fornax to destroy the Tyranical With choice of Battle Suits you can fiy jump over swamps mountains forests plains Battle Heavy Tanks Maulers Flitters Forts You have choice of 5 two Simulation I Ching 16k 4 96 What does the future hold in store Enter PAGE 24 neighbouring planets in Population m om 7 A A 4 Sy LNS amp _ w1 919 df L NrZlSP NSd 1 ANUS gila sin eq 2096 Orange wire on the WD1010 HDC TRSSBIT VOLUME 07 ISSUE 02 JUNE 29013 PAGE 25 60160 19 mati LEA 2298 gt 2dZ0S9ZWV e uini uni vs 15174 ee Y NS d ON yore 513 _ JETJA d Se
206. to high memory The star vanishes and graphics block appears in the next screen position Ad dress FFF is presented at the top of the screen indicating that address is bad The pro gram reads that address as bad because the video memory bank deliberately designed short one bit The video memory ends at ad dreas 3FFF and system RAM bde gins at 4000 This memory loca thon is inadvertently exercised by the program when it begins working over address 4000 its two neighbors It serves as check that Babyroot itself is operating correctly If your n o X mo amp X m FF gt 76 80 Microcomputing May 1080 TRS amp BIT sas TRS BO has a lowercase harc ware modification that saves the extra bit this memory loca tion should read correctly No bad bit will be presented Errors in address 4000 to 41E5 are usually terminal 4166 to 2 might might ot cause significant grief 42E9 and up is where the BASIC programs sit the bad bit coincides with fixed program bit everything will look fine M n is different from a fixed program bit that program might never LIST or RUN correctly if the bad bit co incides with variable location it will be invisible at first But watch those results Reading down trom address you find control informa tion strings and the BASIC stack Errors here can wipe out the program So there ch
207. tor upgrade board the 16K ram bank has been replaced with 4164 ram chips for 64K on board CP M rom switchout which allows full use of 64K Ram all ram mode Z80B CPU replaced the standard Z80 and the computer has a s speedup mod Radio Shack lowercase modification Radio Shack Level II ROM upgrade computer carries cat no 26 1001 so was originally Level I Screen de glitchifier relocated reset button pin header connection on the expansion bus keyboard connector so the keyboard can be disconnected from the mainboard Does work Unfortunately some wires disconnected the Level II Rom chips removed so I think its fair to say this machine was not running when put aside Without the schematics to the modifications it s hard for me to work out what is wrong so I thought I would just let this computer be and it s now a showpiece in John Benson s TRS 80 collection How many super modified Model Is are out there I can only think of who which are more modified than this one neither of which I have seen in person The most well known one would be Dennis Bathory Kitsz Custom TRS 80 he wrote the book about and the other would be Don McKenzie s original Model I which he talks about on his web site lanm trs 80 com REFERENCES 1 www sydtrug org 2 http www trs 80 com cgi bin down ok books pl Custom_TRS 80 and Other Mysteries 1982 Dennis Bathory Kitsz zip 3 http www dontronics
208. ur expensive hard disk drive will plug straight in Tandy also gets kudos for producing products well into the 1980s for their first computer much the same as Apple was still producing peripherals which worked on the original 1977 78 Apple Model I Adapter Kit Includes Adapter cable and diskettes Note May require installation not included oN aaa ene man 69 95 a RT ee RE THE INTERFACE The 26 1132 kit comprises of a small adapter board see photos below with 2 resistors and 2 transistors on it a 3 disk set of what Radio Shack calls Hard Disk OS but is really LDOS 5 1 3 with hard disk drivers TRSHD1 DCT and TRSFRM1 CMD and a JCL to install he hard drive on the Model I and a manual If you follow the instructions you can t go wrong and in about 15 minutes you are up and running with 5Megs of storage in four 1 25Mb partitions and a boot floppy to get the system started While the kit was only listed in the RSCC for only 1982 3 it was available for a couple of years after that while the 5 Meg Disk Systems were still being sold It s hard to say when it was officially no longer available but I suspect sometime around 1986 To EI Screen Printer Port MODEL 1 i HARD DISK ADAPTER MODEL NO 26 1132 To Hard Disk TRSB BIT VOLUME 07 ISSUE 24 DECEMBER 2013 PAGE 25 INTERESTING QUIRKS Yes there are a few If you have used a Model III or 4 with a hard drive you know that
209. ve 1559 00 26 4162 Seis Exp 2099 00 DIDI IDS PAPER TIGERS DID DID MODEL III 26 1061 4K 1 26 1066 48K III W 2 Drives RS 232 20 1103 Drive oec ern 765 00 Dot Resolution Graphics quality print IDS 445G 7 wire printhead graphics List 985 795 00 IDS 460G 9 wire printhead graphics List 1094 886 00 IDS 560G 9 wire wide carriage graphics List 1394 1129 00 Model I PRINTERS 26 1140 Interface 249 00 26 1167 9 Line Printer VII 360 00 26 1141 16K Exp Interface 359 00 26 1166 Line Printer VI 26 1142 32K Interface 469 00 26 1158 Daisy Wheel II 26 1145 RS Board 84 00 26 1165 Line Printer V 419 00 26 1401 Cable 79 00 nected to 231 pin 16 5 voit point Be nection to pin 12 of Z51 on the bottom careful to check your wire wrapping to make sure thal none of pins B are shorted to pins 9 In order to address this new memory we need to create a new line Memory Address 7 Fortunately this is extremely simple 251 7415157 is an address multiplexer and if you examine H you will find that pins 12 13 and 14 are not connected to anything These pins will be used to create our new line MAT First daisy chain all the pins 9 together on the memory chips using your wire wrap wire then connec
210. ve provided yet another means of saving one byte out of our program The instruction JP NZ LOOP takes up a hulking three whole bytes just to tell the 280 to jump back six or so steps We have available a two byte instruction that will do just that It uses the OPCODE JR Jump Relative and is used in exactly the same way Since in two bytes we cannot include all the details for an instruction to jump and the address of any of the 65536 addressable memory locations the use of this command is limited to jumps of plus 127 or minus 128 bytes Now we have a plan so power up Zen and read in the old source file by keying R E and answering the prompts for a filename Since there are only a few lines to change at the end of the program the simplest way is to zap the lines we don t need and key in the new ones Get Zen pointing to line 8 CP 0 which is the first of the ones we don t want and key Z5 E zap five lines This should leave you with just END for line 8 Press E E to enter the editor and key in the following lines TRSSBIT VOLUME 027 ISSUE 02 JUNE 29013 PAGE 16 8 OR lt gt 9 JR NZ LOOP E 10 lt E gt Again note the use of the fullstop to terminate text entry We have now got it into the most compact form so just to make life difficult we are going to incorporate this extremely useful routine into a USR function from Basic There are as you might have guessed just a couple of problems
211. vely lame Priced competitively with the IBM PC XT and much cheaper than the soon to be released IBM PC AT it looked like the 2000 was going to be THE machine to have but that software compatibility problem came back to bite Tandy on the ass Testing most software for the IBM PC XT some 90 didn t work but in fact if the software companies took the time to patch their programs to run on the 2000 you often got the best result A good example of this was 1983 s killer app Lotus 1 2 3 which didn t run on the 2000 in its standard form It took Lotus programmers only 6 hours to patch it work on the 2000 after which they proudly declared the 2000 to be the finest machine to run 1 2 3 on Even Bill Gates sung the praises of the 2000 appearing in an advert for Tandy saying how his latest and greatest invention Windows worked best on a powerful computer with lots of memory and sophisticated graphics and that the 2000 was ideal The only problem was that by the time the computer had been out for 4 months March 1984 it was clear that not many people were buying it It turns out that the minimum requirement to be successful in the PC compatibles world was indeed to be compatible and for most of the software it wasn t If software companies could be bothered to make their software compatible with the 2000 then it worked well exceptionally well look at Microsoft s Flight Simulator 1 0 and Windows 1 0 Ashton Tate s dBASE II and Autodesk s Auto
212. want to manipulate the last character R we have to separate it from the rest of the letters PRESS ENTE To generate the letter R with its bit 7 set could have been achieved by using R 80H but there is a convention with some sense behind it that I wont go into here that it is better to use logical operators wherever possible in preference to arithmetical ones So we are using the assembler s equivalent to the Z280 s OR operation The full stop is used to signify that the bits corresponding to the letter R are to be ORed with 80H which will always result in bit 7 being set VIDEOUT starting at line 7 gets the character pointed to by HL but before displaying it must ensure that bit 7 of the A register is not set This could be don ither by the command RES 7 A RESet bit 7 A but again the logical operation AND is preferred so we have AND 7FH thus filtering out bit 7 The character in can now be displayed but after being output the register is of no use to us as a check on the bit 7 end of string marker To do that we have to refer to the actual string of characters and fortunately the HL register is still pointing to the particular character we are interested in To test bit 7 then is quite easy with the questioning command BIT 7 HL The result will be either a Zero or Non Zero condition in the flag register
213. we call a this in turn looks fixed to an video driver located Normally of be computer reason necessary is into 401DH and everything will There are actually 8 bytes star video display routine the address of your routine in has been for not usi fitted with ng to pu Rom but if som lower case or there s some other the Rom routine then all that is t the details of the new display program course the answer will time hence a still work perfectly ting at 401DH dedicated This block of memory is called It contains some subroutine the current cursor location to the Device t area doing much the same Control Block usually abbreviated to DCB identifying information the address of the actual to handle the character output and a few other bits and pieces There are two other DCB s in tha thing at 4015H there is the keyboard DCB and at 4035H the lineprinter DCB Keyboard debounce was a problem on number of programs scan by picking up executing a delay count before carrying on wit routine Likewise were written that intercep the early TRS 80 s and a ted the keyboard the address from the DCB and simply th the Rom if your printer needs some special then all you have to do is to put the address of your driver module into Basic or
214. whi adi ing enemy fight and aviation experts canino INCLUDING VAT POST TBO FS Va marvel ot modern technology DESCRIPTIVE CATALOGUE OF You ll simply call it fantastic OVER 200 TRS 80 PROG ESSS 3 TE TEL 0734 470425 TRSSBIT VOLUME 7 ISSUE 01 MARCH 2013 PAGE 5 IN MAV S WORKSHOP SUPPLEMENTAL by Ian Mavric CURING MODEL 1 RS232C SERIAL BOARD WOES PART 1 In my capacity as a TRS 80 repair specialist I see lots of hardware and many variations of it that the more casual TRS 80 user may not be aware of Take the humble Model 1 RS232 board which fits inside the Expansion Interface in its own little compartment Most people only think there is one type but there are actually two an early one and a later one Today s discussion will centre around the Baud Rate Generator BRG chip and its power supply circuitry Three main things go wrong with the RS232 board the BRG the UART and the line drivers The most common one being the BRG was called in to help John Benson and Terry Stewart solve a problem which manifested itself as a serial port with a BRG which was overheating and otherwise not working boys noticed that early M1 RS232 boards from 1978 79 had a very pale bluey green circuit board and a BR2941 BRG They were comparing with a later board which has a dark green circuit board and a BR1941 BRG I was able to compare both boards side by side due to having both on hand and could qu
215. which is waved whenever one of the instructions that can affect the flags detects that Bit 7 is set at 1 i e negative We can use this flag in our assembler program decision making by utilising instructions like JUMP if POSITIVE to ADDRESS or CALL SUBROUTINE if MINUS The trio of flags Zero Sign and Carry form the backbone of virtually all the logic in most machine code programs There are three other flags Parity Overflow or P V which some clever people understand Half Carry or E used in decimal arithmetic I think Add Subtract or N again used in decimal type arithmetic but as I ve never had occasion to use them their exact function and usefulness hasn t sunk in yet Back to working out negative numbers a sign bit work out what the others would come to if positive subtract it from the value of Bit 7 and you ve got the negative decimal equivalent Just to show off the Z80 can do the same sort of thing with 16 Bit two byte numbers like OFFFF Hex or 65535 as well In binary it looks like 1 11111111111111 1 as before for the sign Tope u meqepspsqei mq If we added 1 to it like last time we would get 0 so this must be the way 1 Dec would be stored as a 16 Bit two byte number TRS BIT VOLUME 27 ISSUE 01 MARCH 2013 PAGE 20 Now sixteen bit numbers are used a lot in the 780 for memory addresses and one of the things that baffles most BASIC programmers for a while is the problem of PEEKS and P

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