This technical manual was OCR`ed for the Sinclair world by Andy
Contents
1. Ce ana KHD F AT 51 COMPUTER LOGIC Ita pid a IN A nri T LU COC IIIIII T LLL E pl je e i DEW No SRC 049 FIG 6 1A 23A lt SINCLAIR ZX81 b a R15 R16 R17 a ISSUE ONE v RP2 2 9 lt 44 ica u AS 5 B z li i L gt 12 M 4 818 822 f R23 R26 CH oe p tH a ASs a E ED E E u 85 Wd NL Bi LM 421 1853 7 510 385 ON MHC 43 SIDE CS UNDERSIDE A INT HAT TORQ BONO CONNECTOR 1p SV 9v amp 07 D Ad AL ne AI AID AO A9 Ab AS A E amp 2 2 2 MAD 8 TILT 3 4 TTTTTTTT 2 5 9 FRRRAKARRRR AE d za2a5 2 EH x LLL IL LT 828 1 CHANNEL SELECT SWITCH US A Fr 3 7 te 11V OC 7416 741 547 OA 91 diode 0 2 LED RED 0 22. on fi L r ie 4 E v This area amp accessible just UL Ge vi Sx Pi 2 mera d A r i shart 7 ifo umm d Le mundi uh ia 6k af Shape 3 M emery dpe gt WAI Indent Zone de v de en 9 nian a i fin REPEATING w 8 m s LL dl x u amdana u o v To F3 M SEH fo k nd le 2 m M Y d J ZABI KEY matb POR f 725 YN bem KEY Low Purina FC i Cunp eas pe PIN a Pins of jak Pot AERA FICLINE Ta FT Hal 5 CAdT VET T CHANGE CEED AL PEAT Y tet net ie 4 ent m c site C HHS 14 gt Zx key MoD ULE KIT SOCKETS TEM a pw CHIP INTS Pos Tien S SHIM j P cm Pest IN THE To jes Pm lt s EET EN
3. these positions CIO 10nF 10n 103 a Res C11 47nF 473 Z All 65 525 four corour bands the fourth may be gold or silver C12 47pF 47 Value Markings Comments d Semiconductors R1 UK Orange No Type Comment R2 22214 Blue Brown IC1 Sinclair R3 Nor used Logic 1C 40 pirs 158 printed underside Ra Brown Grey Orange 2 2364 24 pins H5 Orange Orange Brown IC3 Z80A or D780C 1 40 pins 86 pu Red Red Hed 4 4118 24 pins A7 63 Yelow Purple Brown or r d 0 IC4a liPD2114LC R3 or IC4b 18 pins FIG 6 5 1 23A SINCLAIR ZX81 aul R15 R16 R17 lt ISSUE ONE RP2 q NG aie x ui Li 2 m U i a 1 1 R1 7 2 C 10 DS i 7 R18 R Cf e Rao os R23 R26 po Fes N wm 2 No zo N k 01 08 po HHHH gt dl alll 25 27 O 00 HANEL SELECT SWITCH USA ONLY r i SV 9 O 8 H HH i op 6 R Sg oF oF mE 070 2 cy AT Unt 16 TVITAPE w lt ICT ON UN 31 SINCLAIR 454 31 KADI COMPUTER MP ay ONY 29 Plt 27 Ket Ov Fr ONLY Frou Riz 5 ptt i 13
4. Q 0 1 2 3 4 5 6 8 95 TO IBID EZ U 14 15 1 16 17 18 19 20 21 22 2J 2 25 26 2 28 29 50 51 2 522 dS M 55 36 37 38 39 40 41 42 43 44 45 46 47 1 48 49 50 51 52 555 54 555 565 57 5 59 60 61 62 65 4 6 6 060 6 68 69 70 71 J2 122 75 75 AC oT 79 5 80 61 62 85 6 95 86 87 88 89 9 93 92 gt 94 95 6 26 97 96 99 100 101 102 103 104 105 106 107 109 209 mo 111 7 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 8 08 129 130 131 132 133 14 135 16 137 136 159 140 141 142 145 2 144 145 146 147 146 149 150 151 152 155 154 155 156 157 158 159 A 16 161 6 16 l6 16 0 19 JO IM I 3 175 B 1 6 177 18 19 ISO 181 182 16 135 06 187 188 159 190 191 192 193 194 195 196 197 198 199 200 201 202 20 204 205 206 207 508 209 210 211 212 51 214 215 216 217 218 219 220 221 222 223 J 2J4 2 5 226 227 226 229 230 231 232 233 2J4 235 236 237 2 8 239 T A M 22 23 2 245 26 2 20 250 51 42 23 2 25 There are fundamental differences between machine Code programming and BASIC prog remmin of the moat fundamental differences is that of LINE NUMBEHS you know every BASIC instruction a program preceeded by a line number zo that the computer wnewa in which order to execute them no line number 13 given the computer will interpret the instruction CCMMAND and will execute it immediately Ir machine code there are no line numbers 150 the ZX30 81 will not al lew
5. L per J Ef ould be used An ordinary He sciewd wer All almost certa rly slip and may cause Markings Comments damage p 1 areae f See the jis of tools g ven in section Tor sthe cece hengi wa Sealine ee Paper 5926 back atthe keyboard and RPI 8 x OK 2 9 into onthe sinus he keyboard 15 self adhesive no necessary two 1 be RP3 5 X OK iok 8 oe as we top wn the keyboard correctly the first time to avoid damaging 1 by cantingal relacz ng 2 EUN ug x eoo Have fi 175 stickit dow ally 22 74 goubl stick Values Markin gs omments the down in one go 476 47 v tier ne aq hat the keyboard connections ire spi securely n place locate the bottom hal the P case 272 56 atto the top with the remaring fie screws Finally ihe rubber feet plug nto four the e S E 2 Electrolytic 16V recesses tne screw heads Fig 11 shows tne ol screws and feet i ee tase iu lvi G 42 tne puter a final check and start using it E zn piae 5 1 Electrolytic 5 mm C6 100pF 100 101 n10 Ceramic disc C7 47pF 47 8 COMPONENT LIST CS 47nF 473 2 Note 1 3 sor corrponenis are marked on the reut board but shown as 6 used ipe pg Do C9 47nF 473 Z not put 1 9
6. 2 PRECAUTIONS There are not many integrated circuits I C s in the kit but they are all fairly expensive items and most of them are susceptible to damage from static electricity There is no cause for worry if a few precautions are taken a Use the sockets supplied with the kit never solder the 1 direct to the board and keep the in their protective packing until you are ready to plug them in b Never insert or remove the C s or do any soldering with power applied to the computer c Use a soldering iron with a properly earthed bit d Carpets and clothing of man made fibres and synthetic soles on shoes are prone to building up a static charge Earth yourself by touching a large object preferably metallic priorto touching the I C s If you do get a shock try changing your clothes or going barefoot seriously 3 COMPONENT EDENTIFICATION Before you start assembly check the components against the component list section 8 and make sure you know what each part is We have tried to cover all different markings of the components but variations are possible Note in particular that the computer s memory maybe supplied eitherastwo 18 pin 1 IC4a amp IC4b or as one 24 pin device IC4 and that assembly is necessarily different for each version Some components need to go in one particular way round a The C s have one end identified by a notch and or a spot or dimpfe nextto pin 1 See 1 Note
7. LED GREEN Mounting Clip for Round Led COMPGILI ITS 4 ACCESSORIES LCE TKS SUGGESTED APPLICATIONS FOR USER FORT amp md D Green 30p MountingClip f 2Sp HID 507 Single Digit Display 11 40p 16 pin DIL Header Plug 60p Op 16 pin Header with 24 Cable Open ended 180p 13 Low current Solid State Buzzer 15 6 Volt Relay Single pole change over contact rating 1A 120V AC 241K 160 Single pole push button 15 1 Loud Speaker 64R 80R 8009 7p SHAPED LEDS Green V532p 21 ink V530p 275 Yellow 523 50 Red Orange V518p 76 Pink V540p 211 Yellow V543P 50 areen V522 PB 42p fellow V553 PB L 42 22 56 V520 p 27 reen V522p Slp fellow V525p 31p rink V320p 27p i amp ES Cana ral 4 0 Cha 40 on channel erp Tus 8 Tua GAM cock QU exile der con o X of 3 Fag e T nk 1 fup 40 yt rm Y i Sak amp vitu Fig fe ben och INCREMENTAL SERIES PLUG amp SOCKET SWITCH SETTINGS APPENDIX B General ITotes ITote the positions of the plug and socket switches see Appendix A and the numbering of the possible positions of the 5 connector plugs Five distinct ranges of positions correspond to different s
8. Select 25 Set if total RAM not more than 16K mbi or Uwe 26 Set if total RAM is more than 16K to MBSA decoder 21 Unused Examples Switch settings Sa lt 4ware Configuration MSA 52 5 1 7 81 with original still on 7 81 board with Incremental containing one 2K RAM chip No external memory 3 19 7 NS 2 7 81 with original IK RAM still on 7 81 board with r cremental containing full 16K of RAM No external memory 3 19 215237 23 3 7 81 with 16K add on pack and original RAM still 5 1 7 81 board bs with Incremental containing 2K of RAM 221 23 26 4 7 81 with IK RAM still on 7 81 board 481 external add on memory with Incremental containing 8K of memory to give 26 the maximum possible directly addressed RAM 50K 6 C 8K ROM 2 19 22 24 INCREMENTAL SERIES RUMIWG ALONGSIDE OTHER MEMORIES General Notes All 5AM pack add ons of 16K or over known to us except for our own have built in disable of the original IK RAM on tho 7 81 board Henoe it is not possible to use the IK RAM on the ZX81 board if such an external memory is in use As well as this it is necessary to roake the Incremental RAM selection agre wdth the ea Uiriial flwyaas c ie the ZE plug must be set for dibble see Appendix B Also it should be understood that the decoding for the IK and 16K RAMS that exist in the 22551 is only partial and ignores bit 15 of tho address If the total RA
9. board Note that if they do not push in freely they may be lightly screwed in Engage the bolts in the nuts soldered to the ends of the bolt guides to take the memory i firmly up to the 7 81 board establishing a rigid structure and firm electrical connectior between the bolt guides and the ZX81 board track Check that the washers are nbt causing shorts on the 7 81 board this can happen if the 7 81 board coatings are worn away the washers are there to prevent such vear from the bolt heads Note that it is possible in this situation to fit the top three memory chips next to the CPU ie it is not necessary to separate the memory board from the 7 81 board in order to them DO NOT FORGET TO KOVE THE HEAT SINK BACK as follows Swivel the heat sink hard up againai the protecting pin on the memory board Failure to do this can cause a disastrous short on the 7 81 board Position the board assembly snug into the 7 81 case top ensuring that the fourcase lugs have cleared the holes provided for them in the memory board Refit the two bolts securing the 7 81 board to the keyboard half of case in the correct positions Note that in this situation the first five memory sockets are accessible as we amp l as all 26 positions of the plug and socket switches Replace the bottom half of 7 81 case the securing of the five bolts can be postponed till testing is successfully completed Test see section on testing REMOVING Remov
10. g bnu pactcs mentioned above INCREMENTAL SERIES HINTS and TIPS Extracting chips from their sockets Take your time The danger is that you are exerting a lot of force and suddenly ons gj end of the chip comes away bending the remaining pins drastically For this reason it a good idea to lever the chip out with a screwdriver or pencil thus avoiding sudden men Care should he takeb when levering not to damage the tracks under the socket if the Soc is of the open window type it is usually possible to actually lever on the socket Note that the chip body is GTctremely rugged it is the pins which are fragile and v hicl will stand only so much bending back and forth Insertion of chips into their sockets THiS 163 more 4 11111 111 than extraction lt Again do not hurry It is possible to align the pins to the socket holes ie getting then straight in line with the rigtfa distance between the rows by grasping the chip firmly by the ends botwe thumb and forefinger and pressing a row of pins flat down on the table being careful to avoid sudden slips Once the pins are reasonably veil aligned the chip should be placed in the socket the right way round with the pins located in the holes in the socket plastic bit not yet in the connectors It can then be jiggled into place keeping a close eye for caught pins which are starting to bend Pin numbers of chips By convention with the chip on the table before you standing on
11. keyboard in front This way you have no untidy twists in your cable FITTING KEYBOARD TO 74490 AND 2x0 Qaem uen es L ZXRO REMOVED p SABLE BN fOsIT ans 65 v Shown UNFERSWE NOT Fis 3 44 15 153 2 5 7 F 0 8 4 KEYBOARD DSE FINGER NUMBERS x Bi COMPONENT FOS fia 2 CONMHECTORS SOLDER WIRES N a 5567 Tim NUMOE UNDERSIDE 2054 27 SINGER NUMOERS 9 0 qe COS P s MOM TING j c C 0 HOLES 39 MEC hovane FITTING TO RS FROW T OFF 4 RUBBER FLET A Remove 3 _ VNDERSIFE SCREWS 2 21 3 2 SCREWS Ai SOLDER T UNDERSIDE OF XISTING KEYBOARD CONNECTOR J RingcH CABLE ES FTER CONNECTING TO KEYBOARD 118 o IC4b pPD2114LC 1 18 pins HEG 7805 5 Volt rerulalor TRI ZTX 313 TR2 313 8 1N4448 Colours Yellow yellow yellow grey or N4148 Yelow brown yellow grey or 15 44 2 Yellow bards some diodes may have their number printed on them instead 9 used CDA 8 SMC 3 lead ceramic filter Other components Modulator type UM1233 3 off 3 5mm jack Spe els for power ear and mic 2 aff In sock 2 afl 3 it S
12. must be made to ensure that the correct length of screw is used in the correct hole The short screws are yellow in colour the long screws are black in colour Fig 11 shows where 4 these locate Serious damage will result if the long screws are inserted in the wrong holes Locate the board on the pillars in the case make sure the jack sockets are behind the holes in the side and screw it into the case Only two holes need screws in them at this point Fig 11 tells you which two the others are for the case bottom fixing Since the screws will have to form their own threads in the plastic they may be a bit stiffto turn the first time therefore it is essential that the proper screwdriver should be used An ordinary flat screwdriver will almost certainly slip and may cause damage to the circuitry when it does See the list of tools given in section 1 iv Turn the case the right way up again peel the protective paper off the back of the keyboard and stick it into its recess in the moulding the keyboard is self adhesive no extra glue is necessary It would be as well to position the keyboard correctly the first time to avoid damaging it by continual relocating Locate the top edge of the keyboard against the top edge of the recess and stick it down carefully working gradually towards the lower edge Have a dry run first if you are in any doubt Do not try to stick the whole surface down in one go v After checking that the keyboa
13. one T Random K Special case will be given T STRUCT LORS FLAGS INSTRUCTION FLAGS Cpeode Hexcode 5 Opcode Hexc ode ADC At table 1 ff1 9 09 HALT 16 ADC HL n tnbjle 2 BA H ADD table 1 O fe ff O IM 6 EWG ADD HL 8 table 2 6 0 amp IM 1 ED ADD IK a table 2 6 0 IM 2 ADD 14 table 2 0 inc 1 table f1P fflO AMD r table 1 1 0 INC m table 2 A n DENN BIT br table 1 7 1 76 r QQ table 1 A O INI EDA 1 71 CALL EDAA 1 7 71 CALL c pq table 2 equala if becomem Q CCF iF x 08 the 1 flag becomes the previous 1NDR EDEA T1 7 T1 value of the C JP pq T 09 PP table 1 n JP c table 5 CPI EDA 0 1 JP HL E9 CPD ENA x x 1 JP qu DIF CFIR EDBL Perl 1 fin theae foul instructions Z 18 JR c e table j 1 if BC becomes 0 and P V 18 1 if A equals LD BC A 02 CPL 2 1 LD A BC OA LD DE A 1 DAA 27 On 8 G LD A DR 1 DE 1 table 1 4 table 2 EMT LD R ELF DINZ Oa l fh A I yh57 668 0 30 0 LO ALR 5 00 0 x d El FY e to interrupt rtorsge EX AF aF 58 I Ia FITI 1
14. the ZX81 Belaya may be controlled from each channel as shown in the application notes and sound output may be produced by connecting a high impendence eg 65 ohm loudspeaker to the ouput plug aa In fig 4 The following programs will produce blips on the loudspeaker 10 EB ZX80 BLEEP 10 ZXB1 BLEEP 20 FOR A 1 TO 10 15 FAST 30 25000 1 20 Kffl A 1 100 40 POKE 25000 0 30 POKE 11000 1 50 HBCT A 40 POKE 11000 0 50 NEXT A To produce a higher frequencies and more interesting effects it 1a necessary to uee a machine code subroutine and complete programs for this on both 2X60 and 81 are given in tha applications notes and in PCW B 1 1 MVIA Il R IIVH I I 4 17 BURNLEY ROAD LONDON NWIO IED Telephone Ol 452 01 450 6597 IBS 2X80 61 Pom KOTES TO ACCOHPAHY KIT The following is provideds Double Bided FOB IOB labelled 1 4 Diode IN9 14 glassy Heslstor IK Capacitors IOOn round and flat 14 Pin Dil Sockets 16 Pin Dil Sockets 20 Pin Dil Sockets 23 x 20 I edge connector 16 Pin Header Plugs 282926 green Translator pack extender card ZX81 only Nae N N Confltraction Begin construction as follows Insert and Bolder in the 6 Sockets putting in the largest ones first Next Bolder in the 2 3 way edge connec tor but if the board is for use with the ZXS1 do not trim short the wires protruding through the undersi
15. tummy components downward Turn 7 81 including ca se round 180 degrees so that heat sink is away from you Lift 7 81 board with left hand slipping memory board underneath it and around the ribbon cab and into poition with the other hand ie so that pins are directly under ZX81 CPU socket Carefully insert pins into 7 81 CPU socket with even pressure from thumbs on CPU body Be extremely careful to be sure that all 40 pins are going in straight and are not bending Do not insert too far into the socket the correct depth of insertion will be automatically attained on fitting the four bolts PTO INCREMENTAL SERIES TESTING 2 lt Having fitted the memory beard to your 2851 now remove anything you may have p in to the expansion port Then i Turn on your 7 61 and ait a few seconds for the cursor to appear i IF the cursor came up as normal THEN GOTO iv 11 cursor hasn t come up so try turning on 7 51 a couple more times If still unsuccessful the problem is almost certainly a bad connection between the memory I and the 7 81 board So IP you have a multitestcr TfiklT Test all 40 pins of the GPU connect through to the ZXSl board Test all 4 bolt guides connect to track on 2 81 board Check that washers are not causing shorts on 2X81 board IF all connections seem OK tlun it 13 likely that there is a fault in the memory board lt end testing failed IF you do not have a circuit tes
16. 53 EX DE HL FB FK 5 HL FY kX SP 1X DPE _____________ayspirx DDF9 SP 1Y FES gm ep FDR EXX INSTRUCTIONS FLAGS INSTRUCTIONS FLAGS Opcode Hexcode Z H FNC Gpcode Hexcode 5S Z H PNC LD rl r table 1 RES b r table 1 LD ran table 2Z HRET Co LD A pq 3Aqqpp RET table J LI 8 p4 table 2 ELAS LD pA 32qqpp LD table 3 RIA 88 EL 1 table 1 FE O O A 0 ALCA i I O LID EDA 0 RLC r table Of 0 80 4 0 BC becomes 0 RLE HP t EDS Le ARA 1F_ 0 0 9 LEDR 60 00 table 0 806 J 1 0 NEG 2 REC r table 0 8 NOP LL RHRD P 0 r table 1 a p 00 CUT D3nn RST 08 1 4 4 QUT PAM table 1 FST 10 22 2557 UTI EDA 7 71 57 EDAB Tx be RST 20 E 65 1 if B becomes zero EDB mes RST 50 M OTDH EDEB 71 0 1 2 POP AP 71 X X X X X x X X SBC table 1 flags are determined by the SBC HL s table 2 10 byte at the top of the etack SCF 31 7 901 table 2 5 b table 1 PUSH F5 OSLA
17. A LINE COPT CLEAR CONT CLS SCROLL WE x PAUSE BREAK SHIFT 72 yw c v B N M LH E xP MKEYE WOT FI SPACE l EO ANO THEN lt ty lt gt p GRAFHICS RuBOUT 1020 5 40 50 6 7889 0 PLOT REM in RUM RAND RETURH IF 6 INPUT POKE PRINT OW WEEN RA U SIH COS IHT ANG ZIR CHAS CODE PEER HEW ne mu FOR 4 UD THON AE S 3 DW F Z GP HE J K L new ARCCOS ARCTAN Sit AUS SCHt VAL LEH USA LINE COPY CLEAR CONT CLA rd L MEXT PAUSE k BRE AK SHIFT 2 X v 8 LN ERP AT IMKEYS PE SPACE YNDERSIDE EXBO PEB I REMOVE 7 RIVETS 2 Remove 5 PEGS 3 CONN BGT AS SHOWN ASSEMBLE EASES SOLDER 15 JOINTS GREEN PURPLE orance 2 9799 SQUEBTE AND e SAS RED Z UME D KEYBOARD adi Efe lt ass RIVETS 21 FERNEY HILL AVENUE REDDITCH WORCESTERSHIRE B97 4RU TEL REDDITCH 0527 61240 PROPRIETOR C LOCKrER RE7 7 KEYBOARD CONSTRUCTION NOTES FireU check the contents of your kit which should contain the tollowrings Quantity Description Quantity Description 1 RE77 FOB 26 Link wire 40 Keyawitchss 8 Sleeving 40 White keytops 18 20 way ribbon cable 40 Clear key covers 1 Legend Set Fit sixteen short wire links a9 shown on fig 1 then fit two long wire links which should have s
18. D As INDICATED 6 P gockET moc 749 5 UNDER D 2 334f A PA Gre S risi Te fe gt K RESISTORS RE Z x9 oro L 4 7 FEET ac QA c Ww Loon Ber THE Jo 3 inei DiolLs M N Wits AS fs DIAGRAM 7 HE TAE Cap Pu TEAS Pea FO Mint AG 5 716 ln THE wu Fr GART TEST Aut KEYS Fo MAKE 50 THEY Arid 54 tet VE REQUIRED SPEED 14 17 INCREMENTAL SERIES DOCUMLHTATI 2 ko I i i i ES UNS go tmm pi He I E i 1 5 gt E Ee DES T LI a t ig RD j gt if 1 i 4 1 E I if 11 T N E d 1 ta i NM 5 41 2 Shou d T 2 4 me b 1 x PLEASE NOTE the position of the 40 protruding pins protected by the clock f polystyrene foam We suggest that this protection be retained until actual fitting Also we strongly recommend the fitting and testing of the memory board as supplied before carrying out any adjustment to switch settings plugging in extra
19. M is not mor than 16K it is as a result of this necessary to mask bit 15 of the address to the Tp rsTnTr decoding and this is the purpose of positions 25 and 26 on the plug and sookei switches if more than 16K RAM exists on the system it will be necessary to usa bit 15 to Clearly differentiate between 16K blocks Please refer to Appendix B for Jaoatiiogs suujjjzh setting abbreviations Note In the following table of switch settings NCroeand No eh iage from the correct setting for Incremental memory running on its own MBSA ZRS BBS TRS 6K KAM packs e g Sinclair Audio Computers etc 5 18 NG 25 32K RAM packs e g Audio Computers Pins 3 14 1C3 Audio Computer board should be directly connected to place second 16KS half of 32K at top of memory ie from address to 64K so that Incremental memory can be ts UN 26 placed in between the halves giving 48K of continuous memory 48K RAM p_acks e g Jfefflo t amp sli The remaining 8K of tho z A aao cr w lt gt J js4o between th 6K snri ti 46K can bo occupied by the Ino3reniOfital board with the following switch settings to give the majtimuB possible directly addresacsd EAL of 56K 6K RAM packs Sinclair Others The Incremental be placed iramGdiately above as follows 2 18 22 54 5 4 18 2 24 25 Others Please call us for advice on any other packs th it vnn r a v i cj iJii
20. an alternative k XC SINCLAIR ZX81 DAW No SRC 049 CHANNEL SELECT SWITCH US OMY 4 To TV FT RE USA USA 3 xbo9 HLY OY 29 21 KBD3 OY From Y 5 9374 197 R ne 11 5 ids 4474 ARETE R 30 USA QNLY ov 7M le MV aie f Ch CY 41 nF SINCLAIR COMPUTER LOGK Ex CONE TOA aah B AB A2 AISA A ADAP AS Ab CS 330 UNDERSIDE 2314 COMPOMENT SIDE g 1K 8 HAM SO APT Ti DA FACE TRA PINS SHOSN CIRCLED HP DD 6 TAR K 902 Jill as
21. arly careful here Vhen construction ifl complete plug in the board apply power to the ZX Again the machine should operate normal if not check that the ICa arq correctly inserted and that there are no board shorts Once the board la functioning there are many tests and experiments that Bay be performed including full freo jency range audio output See arti cISB m Personal Computer World October and November 1981 But here are BOme introductory notes Output Fort Connection to the port are shown in fig 2 There are 8 separate output channels and they may be controlled with a single poke statement 25000 X for the ZXBQ or POKE 11000 for the 81 X may be any integer between 0 and 255 With all output linaa are eet to logic lov whilst 255 Bate them all high To set any one channel high while leaving the remainder low the follow ing valuaa should be used POKE VALUE X CHANNEL ACTIVATED 1 2 1 4 2 8 3 16 4 32 5 64 6 128 7 Thus the command 25000 16 11000 16 the 81 will set channel 4 high leaving the others low Setting a high output on a number of channels ia achieved by combining the data Thus POKEing the value 12 9 4 will set channels 2 and 3 high When a channel goes high it may be used to trigger a variety of devices Fig 3 shows LED indicator lamps attached to channels zero and one To light these execute POKE 25000 3 or POKE 11000 3 on
22. chips etc Finally from bitter experience we think it aorth reading the instructions right through before doing anything else Supplied by EAST LONDON ROBOTICS Finlandia House 14 Darwell Close Fast Ham LONDOS E6 ABT CONTENTS 1 FTTTING REMOVING FITTING OF ADDITIONAL MEMORY CHIPS 2 TESTING TESTING 3 RUNNING ALONGSIDE OTHER MEMORIES General Notes 16K RAM packs 32K SAM packs 48K RAM packs SK RAM packs Others 4 HINTS and TIPS Extracting chips from their sockets Insertion of chips into their sockets Pin numbers of chips APPENDIX Incremental Board Layout Side 1 Incremental Board Layout Side 2 APPENDIX B PLUG amp SOCKET SWITCH SETTINGS General Notes Table of socket positions Examples APPENDIX FOUR This table shows in more or Jean alphabetical order excepi where not convenient each 280 inetructlon and either its hexadecimal code or the worda table 1 table 2 or table J In such cane looking up the appropriate table wili give the hexadecimal code required This appendix also lista the flape that ate altered by each Inatructian Usually will be impasible 10 teat flags and but note that PUSH AF Iollowed p BC allows you tO test all of the flags by then examining the regiater The symbole ward heie are 6 The flag im altered by the Instruction The fing NOT altered by the inetructian o The flag becomes zero 1 The flag becomes
23. d to go in a particular way round just follow fig 4 g The keyboard connectors KB1 amp KB2 have their pins offset from their centre line KB1 goes the opposite way round to KB2 Make sure that in each case the body of the connector covers up the component number on the board See fig 5 h The resistor packs prefix RP have a common end marked with a C on the board i The single resistors the rest of the capacitors and the filter X1 may be put in either way round marked wltn awhlte dot This snould 9 oat tne 4 CIRCUIT BOARD ASSEMBLY The circuit board will be supplied with one side printed with all the component locations this is the side the components go This printing is reproduced as fig 6 See reverse side of sheet since some of the markings will be covered by components All soldering is done on the other side which is coated with a green solder resist this keeps the solder away from where it is not needed The exception is the edge connector area which should be kept free of solder to ensure reliable connection to the RAM pack or printer if they are used We suggest you assemble the components in the following order although it is not compulsory i Resistors capacitors and 1C sockets do not plug the C s in yet ii The diodes and transistors iii The large components the sockets keyboard connectors modulator the regulator and heatsink Finally plug the C s into their socket
24. de of theboard because these will be used for connecting the RAM pack extender card this is not possible on the ZX80 Hot that the edge connector whould have a plaatio plug at pin very careful not to bridge adjacent tracks when soldering this socket To reduce the risk of this you can leave unsoldered any pins that don t appeal to Join up to a track on the underside of the board Insert the two capacitors and resistors and Bolder these Next solder the through connections at all the remaining holes that have solder pads on the upper side of the board except EITHER the three marked A if the board is for use with a ZX81 note that the third A le somewhat obscured by the edge connector OH the two marked B if it la for a 7 60 The through connec tions require a piece of wire to be passed through the board end carefully soldered both sides before clipping off At this point and before inserting the ICs or the diode and transistor plug the board into the 7 80 81 and plug the power plug into the computer The cursor should appear and the ZX should work normally Ifit does not there is a short circuit eomewhere on the board probably between a pair of adjacent tracks The short can be traced after unplugging the board using a multimeter on the ohms range or other continuity tester eg battery and bulb or you can Bsarcb visually If it io a solder bridge then you must reaolder the point but you Day find that you can
25. e all leads from 7 81 Remove bottom of 7 81 case see Fitting Remove the two bolts securing board assembly to keyboard half of case Remove the four 15BA bolts amp washers securing the memory board to the 7 81 board Place a medium size screwdriver between memory board and 7 81 CPU socket and carefully Lever the boards apart being sure not to bend pins as they come out of CPU socket Make sure that the point of the screwdriver pushes on the ZX81 CPU socket and not on board tracks which might bo so damaged FITTING OF ADDITIONAL MEMORY CHIPS Remove 711 leads and attachments from 2861 and remove bottom of case See Fitting Note that the memory sockets are numbered from 1 to 8 see Appendix A and will normally be filled in that order TE ENS RAPERE 596 poh 4 2221 B aam y t keyboatd Halt 6 Carefully place whole assembly with keyboard uppermost and move keyboard to expose memory sockets d not strain the ribbon cable Support the board with fingers as you plug in the memory chip to the first available socket see Hints and Tips LIB Ebo IF Sockets L to Dare not all filled them SIir rrfv 1 Vhen all la well Insert the diode and transistor the correct way around as indicated in fig 1 Finally insert the 4 ICs again consult fig 1 for polarity ICO Inserted the Wrong way artpund will almost certainly ba destroyed when the board IB plugged m so be particul
26. e and any tesis you may have dore Please return to thas address Sinclair Research Service Dept Chesterton French s Road Cambridge C84 eira z 1 3 INSTRUCTIONS _ X Aes s M Mte PE Tasa K10 4 0 ii mr RII 470 iJ TIEN Ka LAT FH2 170 2 v FEYK PEN EAM 5 4 RI3 470 2 e m Xx R14 470 2 Goer NM k R15 220K eel F j Velio SAR rls A e 1 R15 1K lrowr 5 lt jc lt pjsid vut WV RE R17 sae 313 IK quem pit R1 IK 4 STARUS R20 IK wok on id R22 IK R23 1K R24 1K R25 1K rs Amy ENT STE Upi P26 27 R23 6801 gt Blue Giey Brown Founi R29 IM Brown BlacK Green band rr3 be yellow FQ Wri u Pd 331 Mot used 2246 fp js ramage w results ine long screws are inserted the wrong holes P32 TE Not used m Le ate F soard on the pillars n the case are sure the ack socke s we behind ine Poles the R33 AK Veli Purple Red side a 15c the case Only two holes need screws m them at this pori 5 9 1 vou Mo r bas which 50 others are for The 5 Peng INCE TNE j PAVE 10 68 her 2200 Hag Sd Brown thread nthe lt ast c they may P a py SUE o Turn he rs ire therefore 5955868031
27. election functions described in detail below There should normall be one plug in each of these ranges e diLI 1 MB 555050 Start Address 1 0 Start address of ZX81 SK ROM Sse 2 fUt fr Q locatlon above 8K 2 the position in the 64K address ai space the ZXBl microprocessor of the Ace ied position of start of W oard zI Norl T 297 30 that memory ES 37r 1st Tree location Shove 15K pack runs from address upwards 2 42K gt free locatlon above 32K pack 8 56K 9 Nowhere re memory board disabled 10 MBSA Set if no memory on memory board 11 MBSA 2K Set for 2K re 1 chip on m boar lt ZES X91 IK RAM select 42 MB3At4K 2 chips on memory board 13 5 3 Chips 14 MBSA 8K 4 chijs Selects distance above MBSA of the 15 MBSA 10K 5 chips RAM on the 7 81 board thus allowing 16 MBSAFIZK it to be placed diately above 17 MESAT14K chips the memory on the memory board without 18 Ecohere le 2X81 RAM disabled any gaps and used normally I9 Unused 20 Unused BSS Memory Board Block Size daloct 21 Must be set if more than 8K on memory bn r 22 if 8K or less on memory board If you wish the memory board to 23 Set if more than 8K on memory board occupy only 8K of address space must 24 set if 8K or less on memory board set positions 22 and 24 Normal setting 15 21 and 23 for 16K block size TRS Total RAM
28. es off and the regulator gets very hot it isn t bolted to the heatsink properly c If the cursor appears on the screen but the keyboard will not enter check firstly that the keyboard tails are properly in their connectors and not twisted in anyway Also make certain that the diodes and the keyboard connectors are all the right way round d Ifthe screen goes clear but there is not a cursor try disconnecting the power supply and waiting a few seconds before trying again e If horizontal black and white stripes pass through the picture suspect the power supply If you are using your own supply it may need to be better smoothed if the computer is otherwise working or of a slightly higher output See the power supply specification section 9 7 CASE ASSEMBLY i Take the case top the part with the raised Sinclair logo and ZX81 printed on it and feed the tails of the keyboard through the slot at the top right hand corner of the keyboard recess Do not remove the backing paper form the keyboard yet just locate it in the recess see fig 9 Hold the keyboard temporarily in place with a rubber band or a little sticky tape li Hold the circuit board as fig 10 with the keyboard connectors next to the slot with the tails poking through Plug the tails into their respective connectors as shown in the diagram and turn the board over so that the components face into the case top behind the keyboard NOTE Special attention
29. g these instructions making sure there no wire offcuts or similar trapped underneath The keyboard s tails may now be plugged carefully into their connectors the one with 5 stripes goes into KB1 the one with 8 stripes goes into KB2 These tails are quite fragile so handle them gently The keyboard itself should sit the right way up just in front of the circuit board Do not remove the backing paper from the keyboard at this point You may now connect the computer to the T V and power supply and try it out see the main instruction manual for details Once you are sure the computer is working correctly put it in its case see section 7 Do not strain the keyboard connections unnecessarily by using it uncased 6 FAULTFINDING Experience with the ZX80 has revealed that the majority of faults on kits are due to bad soldering If your computer does not work switch it off and CHECK IT AGAIN If you find a bad joint or short shame on youi You should have checked more closely the first time If you are sure the fault is in the circuitry try these tests a If the computer does not work at all leave it on for a couple of minutes and feel the regulator it should be getting warm If not check the power supply and that the plug is in the right socket the one nearest the keyboard Otherwise look at the connection to the T V and make sure it is tuned in properly try between channels 33 and 39 UHF b If the computer works and then go
30. its pins with the indentation at the end of the chip body away from you the pins are numbered starting at J at the far corner on the left down the left side and back up the right side to the far right hand corner It is frequently disastrous to insert chips the wrong way round in their socket iadd apply power ILICHEMEHTAL SERIES FITTING T ud You will require a small conventional screwdriver a small phillips cross headed screw Screwdriver and the ZX81 manual Refer to Appendix A for description of board layout Remove all leads and attachments from your 7 81 Place ZX8l on table before you as for normal use Turn 7 81 over as though it were the front cover of a bock Peel off the footpads located at the HI SW and SE corners of the bottom of the 2X81J Completely loosen the five small recessed bolts which are now visible and lightly replact footpads to avoid losing the three corner screws Lift of the bottom of 2X81 case and put it aside Remove the two additional bolts now visible remembering thai position Note that the 7 81 board is now attached to the keyboard half of the case by just a thin ribbon cable which you must take care not to damage We do not recommend that the ribbon be removed from its socket on the 7 81 board and there is no necessity to do this if thes instructions are followed taking care not to strain the ribbon ca ble turn the 7 81 board not the case over as though it were the top card on a dec
31. k ie the heat sink big rectangle of metal goes under the board and away from you Turn to the chapter in the 2X81 manual entitled How the computer works which contains a picture of what now lies before you Note the positions of the CPU and the IK HAM Take the memory board and find the positions of the ROM CS and the RAM CS depicted thereon With these depictionsuppermost and towards you position the memory board over the 7 81 board with the 40 protruding pins lying directly over the CPU on the 7 81 This is the position of fitting which you should now remember If the Sinclair RAM is socketed rather than soldered to the 7 81 board then remove it and put it aside see section entitled Hints and Tips for advice on removal and insertion of chips Remove CPU from 7 81 and insert it into memory boardbemng sure to match indentation at end of CPU body with paint spot on memory board Remove the 14BA bolts there are 4 and washers from their guides on the memory board Note you could fit the memory board directly in this position but this would necessitate the removal of the ribbon cable from its socket in order to turn the board assembly back on its tummy for reassembly of the case Instead make sure you know the poistion of fitting before going on to next step Swivel the 7 81 heat sink to the extreme right to be sure of clearing thsraemory board when fitting Do not forget to move it back later Turn 2X81 board back on its
32. leeving Put the 40 keyawitches into place Note that the pins in the switches are offset from the centre and if you try to put the switches in the wrong way round the switch body will foul the wire links Having placed the switches putt a sheet of card over them turn the irinted circuit board over and solder the switches Check that all the switches are resting firntlj on the P C B and are straight Fit the 40 white keytops and push on firmly Take the legend set and place it on a firm card Using a Steel rule anda sharp knife cut out the letters using the edge markers as guides You may prefer to draw faint lines and use scissors Using your computer or handbook as a guide place the legends one at a time on the keytop and push on the clear plastic top If you have purchased the RE 77B connector solder the ribbon cable to it 4 of the wires are unused and may be removed If you do not wish to use a connector the cable may be soldered to the PCB The completed keyboard may now be fitted to your 2X80 or ZX8l First study the connection details for your computer Fig 2 and fig 3 More details on figs 4 and 5 Carefully solder the ribbon cable to the computer PCB as indicated The ribbon cable may now be run out of the case underneath the PJYM pack connector Recheck all your soldering then test your computer and new keyboard Fold your keyboard cable under your 7 80 81 Push the computer bo the back of your desk with your new
33. lt 1 6 7 04 2 55628 Woe COPE UHL EEC TE mum 17 19 i DRW No SRU 049 SINCLAIR 81 EDGE CONNECTOR 8 5V9V G OY A1 A A3 AIS Ah A AS AL CS ass DERSE R C 2 13 pF Tm 07 5080720706 35 03 pe PREA 658 ESET BF 1o esr ma m NT HAT BAO M x eee l 1 LL LL III ALL 7 E J 2 1 5 PAMCS a t 16 5 15 21 TK x RAM ed rna u w waw o ee ee x ee r r r 1 Ili 11 1 J I I T j MOT UD o 8 eee s 48 11 212 CI A A w Li s L Titty EC FIG 6 1A 23A SINCLAIR 2x81 l 2 R15 R15 R17 t5 lt lt ISSUE RPS 2 QE 5 lt voc LL T 5 T 11 10 42 D 11 lt R18 R22 1 23 26 01 06 D g WARIH WILL AL SO TIFT 10 d z pr s RH PK Ti R CIRCLED 13 1 24 RAM 18 7 IC4b 6 IN MN HB 1655 Kib
34. ockets or 1 off 4 pin and 2 off 18 pin 1 KB1 Sway keyboard connector KB2 8 way keyboard connector Modulator 1rirn black card Ready made lat keyboard Aluminium bolt and washer for fixing regulator and heats 1 Printed circu board 2 Gase halves 4 Rubber feet 7 Sell tapping Pozdr v screws 3 Blac neg 4 Yellow sear 9 POWER SUPPLY If you wish to use vour own power etn the ZX81 should conterm to nese spectra ons D C only positive to the vp of the 3 5mm jars plug Heed not be regalatzzZ but shou be well smoothed Voltage between 12 volts maxirmurn 277 about volts m depending on smoothing when on load Current not less 600mA or 1 2A othe prater is to work from the same supply 10 SERVICE We will repair yedi completed 281 ed fee o 0 We cannot assemble your kit for you can we start work until the fee 68 rewed In eanonal cases say Earle C s have seen damaged by being put the word nas und wernas ask for an ona jn the other hand f the trouble veas 2 7 fault ance enis supplied 5 wew LA alte full Service fee We strongly advise you rere ea vers zertan that YOU av ster thoroughly for ares before see alsothe hints insectio 6 If vou do retum Zar ZX81 pace aa sno enclose FYING rame and and explaining the sy poms 6 the leci
35. ole ir tha short by passing amp small screwdriver bl between the offending tracks N Input Port Connections to the input port are shown in fig 5 Again there are 8 sep arate channels and they may be read with a single PEEK statement The comm and PHIHT PEEK 25000 the 2X80 or PBIST PEEK 11000 on the 81 will print a value between AND 255 representing the state of the 8 lines If any line la held at logic low it vill contribute a zero to this figure If it is at logic high it contributs a value corresponding to the data on the POKE table above Thus if channels zero and 7 are high bat the rest low the value printed by the PEEK statement will ba 129 128 1 and BO on The circuit of fig 6 shows a single push button eonneated to channel 7 When the button Is pressed channel 7 will go high otherwise it is kept low by the resistor to ground To test the stats of the switch use an expression such B BJ IP PEEK 25000 gt 127 TEHH GO TO 100 X80 or IP PEEK 11000 T 127 THIS GO TO 100 2381 This will cause a jump to line 100 if the switch is closed Note that if nothing ia connected to any channel it will resume a Jjigh state BO that PEEK ing the port with nothing connected should produce a value of 255 If it does not then all board connections should be checked Further applications detaila are given in the applications booklet BAM Pack Extender Card Once the port is working satisfactorily on both Input and out
36. olutely sure you know which version you have got before proceeding IMPORTANT If you have the 24 pin 4118 in your kit a short wire link should be inserted in the holes at position L1 Use a component lead off cut for this DO NOT do this if you have two 18 pin 2114s and do not put anything in position L2 e When mounting the regulator do not bend its leads too close to the plastic Bolt it down firmly with its heatsink before soldering f Put the modulator s wires through the holes marked Fr UK1 and UK2 Put each lead through the hole it is nearest to do not cross them over Do not try to bend the thick pins on the modulator hold it in place by hand whilst soldering The black card trim is a push fit over the aerial socket g The will have their pins splayed out slightly and you may need to push them inwards slightly e g by pressing against a flat surface before they will fit the sockets Make sure that each pin has in fact gone into its respective socket and that none are curled up under the C 3 5 TESTING The completed board should now checked verythoroughly for stray blobs of solder dry joints leads not trimmed etc Also make doubly sure that all components are in the right place and the right way round and that the stand up resistors are not touching anything else If everything seems in order the board may be tested before you put it in the case Rest the completed assembly on an insulating surface e
37. orrections to the circuits issued In the applications booklet and in PCW In all applications using ths high impedance loudspeaker this should be connected via a 10 mfd capacitor to earth as shown in fig 4 of the attached sheet and not directly to the positive supply as in PCW 2 In all applications of the solid state buzzer this should be connected between the particular channel that it la used with and the positive supply pin 16 rather than earth pin 9 polarity of the buzzer should also be reversed so that its red lead la on the positive supply It will function aa connected in the applications circuit but it works more effectively as described here Loudspeaker A suitable loudspeaker for audio output may be obtained from Technomatio Limited at 50 TAT wr Clear A6 Les pen EX cone eR EMER saan C i Pu moam eee 9 gas 5 TF mp w T C w eS tet 41 CS lii o Rie ye e I 2 i byf ghee piv Air Se EUM ATIK C HOT 7 2 5 79 as MN nx wt d le l ii 7 2 x S 1 4 3 f f ve 7 4 gt 1 a 1 lt lt NTC 4 4 O 4 gg iden PE PCR AES f L Cre lt d lah 1 ACA IST ex 1
38. pot SEMI APPROVED This technical manual was OCR ed for the Sinclair world by Andy Dansby andydansby yahoo com All intellicial information contained inside this technical manual is the property of Amstrad Read through the instructions before you start assembly lf anything seems unclear or difficult contact us for advice before going ahead 1 PREPARATION You will need a clean dry and well lit workspace in which to assemble your kit If possible try to find somewhere where the parts can stay undisturbed in case you do not finish the kit all at once It is a good idea in any case to split the work up say assemble the circuit board one eueninn tben tffst jt and put the case together the next evening You will need these tools a A light electric soldering iron say 15 to 25 watts with a fine tip b Fine gauge solder with resin flux core NOT acid flux c pair of sharp sidecutters d A Pozidriv screwdriver with a No 1 point e A medium size ordinary screwdriver and or a 4B A spanner The following items are optional but useful a A magnifying glass for examining solder joints and looking for short circuits b Some desoldenng braid or other solder removing tool Better still take care that you put the components in right the first time removing them can be very difficult A piece of foam is useful to stop components falling out when you turn the board over to solder them
39. put the extender card should be soldered in Shis allows the simultaneous use of the RAM pack and port boaid on the 81 though this IB not possible on the 7 80 The extender card solders to the rear of the edge connector to effectively extend the extension plug at the rear of the 2X81 See Figs 7 t 8 to wire up the card first bend the edga connector pins towards each other so that the card Just fits between them Then position the card between them as in Figa 7 and 8 The card should he positioned with notch outwards i e away from the main port board and exactly at ri at angles to the port board How care fully solder the 22 upper and 22 lover pins to the extender card keeping the card at right angles to the main board When you have checked that there are no solder bridges you should be able to plug the RAH pack into the extender card and the port onto the 81 To use this tandem arrangement satisfactorily the 7 01 and extensions should be kept on a flat surface to avoid poor contacts through flexing of the board If the system fails to operate with the HAM connected try flexing the arrange ment and reinserting the paver plug boards should be inserted as far as they will go Hote when using the RAM pack aa well aa the port board you will not be able to drive so many external devices lamps relays eto with the output port If in doubt check that ZX81 ia not getting too hot Errata There are two rranor c
40. rd connections are still securely in place locate the bottom half of the case and screw it to the top with the remaining five screws Finally the rubber feet plug into four of the recesses over the screw heads Fig 11 shows the location of screws and feet vi Give the computer a final check and start using it 8 COMPONENT LIST Note that some components are marked on the circuit board but shown as not used in this list Do not put anything in these positions a Resistors All resistors have four colour bands the fourth may be gold or silver No Value Markings Comments R1 10K Brown Black Orange R2 680 Q Blue Grey Brown Rg NOt used R4 18K Brown Grey Orange R5 330 Q Orange Orange Brown R6 2K2 Red Red Red R7 470 Q Yellow Purple Brown H8 470 Q H9 470 Q R10 470 R11 470 Q R12 470 fi R13 470 2 R14 470 2 R15 220K R16 IK R17 1K R18 1K R19 1K R20 1K R21 1K R22 K R24 IK R25 1K R26 1K R27 1K R28 680Q R29 1M R30 R31 R32 R33 4K7 R34 220Q b Resistor Packs No Value RP 1 8 x 10K RP2 RP3 5 x 10K c Capacitors No Values C1 47pF C2 47nF C3 22uF C4 47nF C5 C6 100pF Ci 47pF C8 47 9 47 IOnF Cll 47nF C12 47pF Semiconductors No Type IC1 Sinclair Logic 1C 2 2364 Z80A or D780C 1 4 4118 or 4 uPD2114LC or as IC4b Hed Hed Yellow Brown Black Red Blue Grey Brown B
41. rown Black Green Yellow Purple Red Red Red Brown Markings 10KQ 10KQ Markings 47 473 2 22 H 473 Z 1 i 100 101 nlO 47 473 Z 473 Z lOn 103 473 Z 47 Comment 40 pins 158 printed underside 24 pins 40 pins 24 pins 18 pins Fourth band may be yellow Not used Not used Not used Comments 9 leads Not used 6 leads Comments Ceramic disc Electrolytic 16V mm Ceramic disc Electrolytic 5V min Ceramic disc IC4b uPD2114LC 1 18 pins HEG 7805 5 Volt regulator TRI ZTX313 TR2 ZTX313 D1 D8 1N4448 Colours Yellow yellow yellow grey or 1N4148 Yellow brown yellow grey or 1544 2 Yellow bands Some diodes may have their number printed on them instead I9 Not used X1 CDA 6 BMC 3 lead ceramic filter e Other components Modulator type UM1233 3 off 3 5rnm jack sockets for power ear and mic 2 eff 40 pin 1C sockets alee f oti 24 Bin er JKR Se csockets 1 5 way keyboard connector KB2 8 Way keyboard connector Modulator trim black card Ready made flat keyboard Aluminium heatsink 4BA nut bolt and washer for fixing regulator and heatsink Printed circuit board 2 Case halves 4 Rubber feet 7 Self tapping Pozidriv screws 3 Black long 4 Yellow short 9 POWER SUPPLY If you wish to use your own power supply with the ZX81 it should conform to these specifications D C only po
42. s The general procedure for each component a Identify the part and its position on the board and insert it into the appropriate holes bending the leads if necessary But see later In the case of components with a number of pins make sure that they have all gone through their holes b Hold the part in position if you bend its leads to do this do not press them fiat onto the board as this will make them difficult to cut and will encourage short circuits c Solder all the wires on the green side of the board and if they are long trim them with the side cutters No lead should stick out more than about 3mm or V from the solder side Some components need more detailed explanation a The capacitors are represented by a capacitor symbol on the board rather than a box as the rest of the components are Fig 7 explains how they fit in the board relative to the symbol FIG 7 CAPACITOR me CYAN HOLES TO USE b There are four oblong boxes labelled R7 R10 R11 R14 R18 R22and R23 R26 These all contain a row of resistors standing on end as in fig 8 Take care when mounting these the length of bare wire up the side should not be allowed to short against anything else c IC2 and IC4 have two different sized boxes printed on the board use only the holes corresponding to the smaller box d As previously mentioned 4 be in either one or two packages Only the appropriate 1C Sockets will be supplied so make abs
43. sitive to the tip of the 3 5mm jack plug Need not be regulated but should be well smoothed Voltage between 12 volts maximum and about 8 volts minimum depending on smoothing when on load Current not less than 600mA or 1 2A of the printer is to work from the same supply 10 SERVICE We will repair your completed ZX81 kit fora fixed fee of 10 00 We cannot assemble your kit for you nor can we start work until the fee is received In exceptional cases say if the t C s have been damaged by being put in the wrong way round we may ask for an additional payment On the other hand if the trouble was due to faulty components supplied by us we will reiui j the full service fee We strongly advise you therefore to be very certain that you have checked the computer thoroughly oi mistakes before returning it see also the hints in section 6 If you do return your ZX81 pack it well and enclose a note giving your name and address and explaining the symptoms of the trouble and any tests you may have done Please return to this address Sinclair Research Service Dept Chesterton Mill French s Road Cambridge CB4 3NP Sinclair Research Limited 1981 i eer he ip fu SK 3 ap ad aa Pe nap an ee 45 4 3 436 ean r CMPOHURT 010 0505 65 NX L ee 2 eee t 3 3 Il I L l j lj It i HL TOOT THUD
44. table 1 g PUSH s table 2 SHA r table 1 RR 0 FO SRL table 1 pm m ggos SUB T table 1 1 XOR 1 table 1 0 00 OLD ROM SYSTEM VARIABLES APPENDIX SIX Decimal Hex TEE 16385 16366 16388 16 550 1650 16394 16396 16398 16400 16402 16405 16405 16407 16409 18410 6415 16414 16416 16418 16420 16422 4000 4001 4002 4004 4006 40 4004 4000 4008 4010 4012 4013 4015 4017 4019 401A 40 40 4020 4022 4024 4026 Name ERR HR FLAGS PPC E ADDR E PPC VAHS E LIWE D FTLE DF EA DF END DF SZ s TOF X PTR OLDPPC FLAGA T ADDR SEED FRAMES Y ADDR 5 POSN CH ADD HEW ROM SYSTEM VARIABLES Decimal Hex Name 16364 4000 16385 4001 FLAGS 16366 4002 ERR SFE 16366 4004 RAMTOP 16390 4006 MODE 16391 400 PPC 16593 4009 VERSN 16394 400A E PPC 16396 400C D FILE 16598 400E DF CC 16400 4010 VAHS i6402 4012 DEST 16404 4014 E LINE lo406 4016 CHADD 14058 4015 1610 STKBOT 6112 ADC STKEND 16414 401E BERG 10415 401 16417 402 SPARE 16418 4022 5 15119 4023 STOP 16421 4025 LAST K 16423 4027 DEST 16424 4028 MARGIN 16425 4029 NXTLIN 16427 4028 OLDPPC 16429 402D FLACX 16430 402E STRLEN 16432 4030 T ADDR 164134 4032 SEED 16426 4034 16438 4036 COORDS 19440 4038 19441 4039 5 POSN 15443 4055 CDFLAG 16444 403 PRBUFF 165477 405D MEMBOT 16507 4078 SPARE
45. ter then removs the memory board and check that no pins are bent over If they are it ray b possible to straighten it again without breakage If one breaks then there is nothing for it but the soldeeing iron iv Find out the contents of RAMIOP s e ZX8l manual if interested as follows Type in PHIHT PEEK 16389 the result will come up on ths screen and should be checked against ths table below Note that if the original IK RAM has been removed from the 7 51 board that the RAMTOP value should be 4 less than the figure in the table If this is the case and RAMTOP is correct then you may plug in the removed IK chip if it is of course to the first available socket on the memory board at the same time you ought to move the plug selecting the PJHI to disable position 18 to avoid the 2X81 decoding fighting ths memory board decoding and consuming unnecessary current TABLE of correct HAAiTO values Sfp of 2K chips fitted to memory board Corresponding value of RAMTOP 68 76 84 22 100 LOG LLG 1 24 128 OJ ANU O RAMTOP does not correspond to the number of memory chips then Jfote tie actual value obtained Obtain the value of location 16388 type in PRINT PEEK 16388 to get this and note Call us end 1 2 INCREMENTAL SERIES PITTING Continued Position the four bolts and washers back into their original positions except that now of course they pass through corresponding holes in the 7 81
46. that all the C s face the same way on the board i e with their notches towards the edge connector 1 AG 2 SURFACE i BANDS 7 FIC 3 ELECTROLY TIC CAPACITOR Lu ALTERHATINVC PAINTED BLOCK ON Although the C sockets do not need to go any particular way round you may like to put the bevelled corner at the notch end of the position as a reminder since the semicircie printed on the board will be covered by the socket in some cases b The diodes prefix D have their end identified by the band painted on the body or in the case of components with several bands the end will be the widest band This corresponds to the flat bar of the symbol printed on the board See fig 2 The electrolytic capacitors C3 amp C5 will have a or symbol printed on them and the wire is usually longer See fig 3 d The transistors prefix TR go in the board as shown by the picture printed at their positions i e with their rounded corners facing the edge connector e The jack sockets and modulator need to have their business ends i e where the plug goes in facing outwards away from the components This should be obvious by inspection of the board and Case FIG mur di WASHER ae REGULATOA e 8 PIN CONECTOR HEAT i END VIEW 5 8 PIN CONECTOR END VIEW PC 8 BOLT f The regulator REG and heatsink nee
47. you to use machine code inatruoction as commans they MUST form part cf program The instructions are executed the order that they are stored For example if the computer had just finished executing the Lnetruction which wea in location 300M it would then go tc ezecute the instruction held location 3000 It will continue in this way until it recieved inatruction telling to do otherwise Unlike will NOT automaticly stop when it the end of the program It will pleugh right on through the address s and every time it finds number which is not zero will simply treat that rnmber as a code for nome in amp truction and try to execute Usually this will result in what is called CRASH ABOUT CRASHING Crashing is8 the name we give to what happens when your up until now at least moderately well behaved Sinclair machine urmittingly tries to execute something it shouldnt or 1f there a drastic mistake in your macnineecedirg which will EDIT AHG THES T c3 gt gt GRAPHICS AUBOLT I I 2830 40 50 7 859 0 PLOT UHPLGT REM RUM RAND AETYAM IF INPUT PRINT Hu gt H OM WE EF RA TA YS 1 0 P INT AAG STR CHES CODE PEEK TAB HEW on SNE uT FOR a GOSUE LOAD LET FUNCTION J K L w ARCSIM ARCCOS SGN ARS SGR VAL LEN US
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