Home

OS-9 BASIC User Manual

Contents

1. RUN hexdemo 00000064 0064 01C0000000000000 414243 00000001 01C0000000000000 Chapter 12 Files and Unified Input O utput String Format Syntax Swj Function String format is used to display string data of any length The w field width specifies the total field size If the string to display is shorter than the field size it is padded with spaces according to the justification mode If it is too long it is truncated on the right side The justification modes are Mode Description gt Right justify a Center justify Examples PROCEDURE stringdemo PRINT USING S9 lt HELLO PRINT USING S9 HELLO PRINT USING S9 HELLO END RUN stringdemo ELLO HELLO HELLO tan 12 23 Chapter 12 Files and Unified Input Output Boolean Format 12 24 Syntax Bwj Function Boolean format displays boolean data The result of the boolean expression is converted to the strings TRUE and FALSE The w field width specifies the total field size If the string to display is shorter than the field size it is padded with spaces according to the justification mode If it is too long it is truncated on the right side The justification modes are Mode Description lt Left justify default if mode omitted gt Right justify s Center justify Example PROCEDURE booldemo END
2. PARAM n m d 1000 INTEGER IM i INTEGER OR i n TO m PRINT d i EXT i RINT CEDURE sortest E This procedure is used to test Quicksort E It fills the array d with randomly generated E numbers and sorts them IM i d 1000 INTEGER OR i 1 TO 1000 d i INT RND 100 EXT i UN prin 1 1000 d UN qsort1 1 1000 d UN prin 1 1000 d Appendix A Sample Programs The following procedures demonstrate multiple precision arithmetic in this case using five integers to represent a 40 decimal digit number with eight fractional places PROCEDURE upadd REM atb gt c five_integer_number T F Ritter PARAM a 5 b 5 c 5 INTEGER DIM i carry INTEGER carry 0 FOR i 5 TO 1 STEP 1 c i a i t b i carry IF c i gt 100000000 THEN c i c i 100000000 carry 1 ELSE carry 0 ENDIF NEXT i PROCEDURE upsub PARAM a 5 b 5 c 5 INTEGER DIM i borrow INTEGER borrow 0 FOR i 5 TO 1 STEP 1 C i a i b i borrow IF c i 0 THE C i 2c i 4100000000 borrow 1 ELSE borrow 0 ENDIF NEXT i PROCEDURE uprint PARAM a 5 INTEGER DIM i INTEGER s STRING FOR i l TO 5 IF i 5 THEN PRINT ENDIF s STR a i PRINT RIGHTS 00000000 s 8 NEXT i
3. END RUN intdemo 10 10 010 12 21 Chapter 12 Files and Unified Input O utput Hexadecimal Format 12 22 Syntax Hwj Function Hexadecimal format can be used to display the internal binary representation of any data type using hexadecimal characters The w field width specifies the total field size If the hexadecimal representation to display is shorter than the field size it is padded with spaces according to the justification mode If a representation of a numeric is too long it is truncated on the left side see the second line in the procedure and its matching output below Representations of STRINGS that are not allowed a large enough field are truncated from the right The number of bytes of memory used to represent data varies according to type The following specifications are the minimum required field widths to display the entire hexadecimal representation for each data type Specification Description H2 Boolean byte one byte Boolean byte one byte Left justify with trailing spaces default H8 Integer four bytes H16 Real eight bytes Hn 2 String of length n The justification modes are Mode Description lt Left justify with trailing spaces default gt Right justify leading spaces Center justify Examples PROCEDURE hexdemo PRINT USING H8 100 PRINT USING H4 100 PRINT USING H16 1 5 PRINT USING H8 H10 H20 ABC 1 1 5 END
4. CREATE trans transactions UPDATE CREATE spool user4 report WRITE CREATE outpath nameS UPDATE EXEC Chapter 12 Files and Unified Input O utput CLOSE Close Path Syntax CLOSE lt path num lt path num Function CLOSE notifies OS 9 that one or more I O paths are no longer needed The paths are specified by their number s If the closed path used a non sharable device such as a printer the device is released and can be assigned to another user The path must have been previously established by means of OPEN or CREATE unless you immediately open a new path to take over the ATTENTION Paths 0 1 and 2 should never be closed standard path number Examples CLOSE master trans new_master CLOSE 5 6 9 CLOSE 1 closes standard output path OPEN path T1 Permanently redirects Std Output CLOSE 0 closes standard input path OPEN path TERM Permanently redirects Std Input DELETE Chapter 12 Files and Unified Input O utput Delete File Syntax DELETE pathlist DELETE deletes a mass storage file The file s name is removed from the directory and all its storage is deallocated Any data in the file is lost The pathlist must be within quotes A string variable is allowed It is evaluated and passed to OS 9 as the descriptive pa
5. wi work_rec name work_rec list 0 work rec cost 0 work_rec qty 0 FOR n 1 TO 100 PUT path work_rec NEXT n Important The assignment statements reference each named field of work_rec by name but PUT references the record as a whole Chapter 12 Files and Unified Input O utput The following subroutine requests a record number then requests data and writes it in the file at the specified record INPUT Record number recnum INPUT Item name work rec name INPUT List price work rec list INPUT Cost price work rec cost INPUT Quantity work rec qty SEEK path recnum 1 SIZE work rec P UT path work_rec This routine uses a loop to read the entire file into the array inv array SEEK path 0 rewind the file FOR k 1 TO 100 GET path inv_array k NEXT k Because entire structures can be read you can eliminate the FOR NEXT loop with the following SEEK path 0 GET path inv_array This example is simple but it illustrates the power of BASICO9 s complex data structures and the random access I O statements When fully exploited this system has the following important characteristics tis self documenting You can clearly see what a program does because structures have descriptively named sub structures tis extremely fast Programs are simplified and require fewer statements to perfo
6. 2 20 Chapter 2 Getting Started In this example the procedure will not execute until the line containing the error is deleted Therefore you should re enter edit mode and use the 1 command to list your program B e mtable PROCEDURE mtable 0000 DIM a b INTEGER E 1 0000 DIM a b INTEGER 0012 a 1 0020 PRINT 0024 WHILE a 10 DO 003A b 1 0048 WHILE b lt 10 DO 005E PRINT a b a b TAB MOD b 5 13 0098 IF POS gt 55 THEN PRINT 00BO0 ERR ednif 00BA ENDIF OOBE b b 1 00D2 ENDWHILE 00DC PRINT OOEO a a t1 OOF4 ENDWHILE OOFA END he Notice that the first line of the procedure is displayed with an asterisk before the line This points to the location of the edit pointer Because the error is on line nine of the procedure you must move the edit pointer to line nine You can use the lt num gt command to do this If you redisplay the procedure with the 1 command after executing this command the asterisk is now in front of the ninth line E 9 00BO ERR ednif The d command deletes the line E d 00BO ENDIF 2 21 Chapter 2 Getting Started 2 22 You can now exit edit mode by typing q and run the procedure mtable 1 1 2 2 dL og 6 1o 7 Th A 2 2254 3 26 12 2 14 i 16 226 3 18 i 21 24 4 4 2 4 3 12
7. ProcLine ProcLine ReOutput 4DestDir t FileName ENDIF ProcLine ProcLine 4Options WRITE ProcPath ProcLine DLE ial z WHILE j i AND MID DirLine j 1 DO j j 1 ENDWHILE UNTIL j i ENDIF ENDWHILE WRITE ProcPath TMode 1 pause WRITE ProcPath Dir e SrcDir IF DestDir THEN WRITE 4ProcPath Dir e 4DestDir ENDIF OSE DirPath OSE ProcPath HELL del procmaker dir RINT t9 y QO INPUT Another response UNTIL response lt gt Y AND response y IF response lt gt B AND response lt gt b THEN BYE ENDIF A 18 Appendix A Sample Programs 361 SysCall a subroutine for Basic09 68000 si d Called by RUN SysCall Code Regs A El Code An integer contained the OS9 function code a Regs Register pack must be at least 48 bytes for ze registers DO thru A4 a use lt oskdefs d gt d Definition of Parameters on Stack org 0 Return do 1 1 Return Address Length1 do 1 1 Length of first parameter Param2 do 1 1 Address of second parameter Length2 do 1 1 Length of second parameter psect SysCall Sbrtn lt lt 8 Objct ReEnt 8 1 0 0 SysCall SysCall cmpi l 2 d0 check parameter count bne s ParamErr branch if error cmpi l 4 Lengthl a7 is first parameter integer bne s ParamErr branch if not cmpi l 52 Length2
8. END This works if the Phonebook file does not yet exist However trying to CREATE an already existing file causes an error 218 To access an already existing file use the OPEN statement The OPEN statement has the same syntax as the CREATE statement OPEN lt int or byte var path access mode There are five access modes that the OPEN statement uses Access mode Description READ Reads data from a file WRITE Writes data from a file UPDATE Allows you to read and write to a file EXEC Looks for and stores your file in your execution directory DIR Opens a directory for read only You can OPEN a file in more than one mode if the combination is valid For example OPEN file example READ EXEC Important DIR and either WRITE or UPDATE causes an error READ WRITE is the same as UPDATE 3 7 Chapter 3 Program Construction Complex Data Types and Subroutines Using A Random Access File To illustrate the access capabilities of random access files examine this procedure PROCEDURE Phonebook YPE rec street STRING 30 cityst STRING 30 zip STRING 9 YPE ENTRY name STRING 30 phone STRING 20 address rec DIM Phonebook ENTRY DIM file record INTEGER DI flag BOOL
9. PRINT IS 10 4 PRINT USING B9 10 4 PRINT IS 4 10 PRINT USING B9 4 10 RUN booldemo IS 10 4 FALSE IS 4 10 TRUE Control Specifications Repeat Groups Chapter 12 Files and Unified Input O utput Function Control specifications are useful for horizontal formatting of the output line They are not matched with items in the output list and can be used freely The control formats are Mode Description Tn Tab to column n Xn Space n columns str Print constant string The string must not include single or double quotes backslash or carriage return characters ATTENTION Control specifications at the end of the format specification list are not processed if all output items have been exhausted Example PROCEDURE demo PRINT USING addr X2 H4 X2 data X2 H2 1000 100 END RUN demo addr 03E8 data 64 Function Many times identical sequences of specifications are repeated in format specification lists The repeated groups can be enclosed in parentheses and preceded by a repeat count These repeat groups can be nested Examples 2 X2 R10 5 is the same aS X2 R10 5 X2 R10 5 2 12 2 X1 S4 is the same as 12 X1 584 X1 84 12 X1 84 X1 84 12 25 Appendix Sample Programs This appendix contains 24 example procedures that can be used immediately or studied and adapted for use within user procedures The procedures
10. This procedure prints one of two messages depending on your input The condition could also depend on a computed value Also there could be many statements or procedures separating the THEN and ELSE segments of the conditional This example just shows one of the ways you can use this structure You can also use the IE THEN statement as a single statement IF boolean THEN lt line gt This sends the control of the procedure to the specified line number if the control condition is met You should rarely use the IF THEN statement in this way Important Multiple ELSE statements are not considered errors by the compiler that is they do not generate error signals However they do produce irregular and non reliable results 2 12 Looping Statements Chapter 2 Getting Started When you write your programs you may find that you want to repeat a section of code several times You can do this using a looping statement Loops cause repeated or conditional execution of the statements located between the starting point and the ending point of the loop Generally loops have one entry at the top and only one exit at the bottom In this sense it becomes one statement regardless of how many individual statements it contains You can nest loops This allows the internal statements to be executed even more times You should know at least what will happen on the first second next to the last and last passes through the lo
11. Appendix A Sample Programs PROCEDURE upinput PARAM a 5 INTEGER DIM n i INTEGER DIM b STRING 64 INPUT input ultra precision number bS b TRIM S b n SUBSTR b IF n 0 THEN a 5 VAL MIDS b 00000000 n 1 8 b LEFTS b n 1 ELSE a 5 0 ENDIF bS 00000000000000000000000000000000 bS n 1 LEN b FOR i 4 TO 1 STEP 1 n n 8 a i VAL MIDS b n 8 NEXT i PROCEDURE uptoreal PARAM a 5 INTEGER b REAL DI i INTEGER b a 1 FOR i 2 TO 4 b b 100000000 b b a i NEXT i b b a 5 00000001 PROCEDURE ultra DIM one 5 two 5 out 5 INTEGER r REAL UN upinput one RUN upinput two PRINT add RUN upadd one two out RUN uprint out PRINT RUN uptoreal out r PRINT r PRINT sub RUN upsub one two out RUN uprint out PRINT RUN uptoreal out r PRINT r Appendix A Sample Programs PROCEDURE Patch Program to examine and patch any byte of a disk file Written by L Crane DIM buffer 256 BYTE DIM path offset modloc INTEGER loc REAL DIM rewrite STRING INPUT pathlist rewrite OPEN path rewrite UPDATE LOOP INPUT sector number rewrite EXITIF rewrite THEN ENDEXIT loc VAL rewrite 256 SEEK path loc GET path buffer RUN Dump
12. Data Types and Data Structures When a STRING value is assigned to a STRING variable the bytes composing the string are copied into the variable storage byte by byte The beginning of a string is always character number one and this is not affected by the BASEO or BASEI statements Operations which result in strings too long to fit in the dimensioned storage truncate the string on the right and no error is generated Normally the internal representation of the string is hidden A string is stored in a fixed size storage area and is represented by a sequence of bytes terminated by the value zero or by the maximum length allocated to the STRING variable Any remaining unused storage after the zero byte allows the stored string to expand and contract during execution The example below shows the internal storage of a variable dimensioned as STRING 6 and assigned a value of SAM Notice the byte at 3 contains the zero string terminator and the two following bytes are not used 0 1 2 3 4 5 If the value ROBERT is assigned to the variable the zero byte terminator is not needed because the STRING fills the storage 0 1 2 3 4 5 A BOOLEAN data type can have only two values TRUE or FALSE They are stored as single byte values but they may not be used for numeric computation A variable may be typed BOOLEAN DIM done_flag BOOLEAN BOOLEAN values print out as the characte
13. Exponential format prints numbers of types REAL INTEGER or BYTE in the scientific notation format using a mantissa and decimal exponent The syntax and behavior of this format is similar to the REAL format except the w field width must allow for eight overhead positions for the mantissa sign decimal point and exponent characters The justification modes are Mode Description lt Left justify with leading sign and trailing spaces This is the default if justification mode is omitted gt Right justify with leading spaces and sign Example PROCEDURE expodemo PRINT USING E12 3 1234 567 PRINT USING E13 5 0 001234 PRINT USING E12 2 1234567 END RUN expodemo 1 235E 003 1 23400E 003 1 23E 006 Integer Format Chapter 12 Files and Unified Input O utput Syntax Iwj Function Integer format is used to display numbers of types INTEGER or BYTE and REAL numbers that are within range for automatic type conversion The w field width must allow for one position overhead for the sign The justification modes are Mode Description lt Left justify with leading sign and trailing spaces default if justification mode omitted gt Right justify with leading spaces and sign i Right justify with leading spaces and trailing sign financial format Example PROCEDURE intdemo PRINT USING I4 10 PRINT USING I4 10 PRINT USING I4 10
14. ie Z DIF ial zZ 9 3 16 Formatted Output The PRINT USING Statement Chapter 3 Program Construction Complex Data Types and Subroutines BASIC has a powerful output editing capability for generating reports and other applications where formatted output is required The output editing uses the PRINT USING statement PRINT lt path gt USING lt str expr gt lt output list gt The string expression is evaluated and used as a format specification This contains specific formatting directives for each item in the output list The lt path gt is optional and can redirect the output to the corresponding device Important Blanks are not allowed in format strings The items in the output list can be constants variables or expressions of any basic type As each output item is processed it is matched with a specification in the format list The type of each expression result must be compatible with the corresponding format specification If there are fewer format specifications than items in the output list the format specification list is repeated again from its beginning as many times as necessary A format string has one or more format specifications separated by commas There are two kinds of specifications those that control output editing of an item from the output list those that cause an output function by themselves such as tabbing and spacing There are six basic output editing di
15. remove queen from square n h n n 1 COl h TRUE Nup n h 7 TRUE down nth TRU ENDIF h h 1 UNTIL h 8 ND LH s A 5 Appendix A Sample Programs PROCEDURE electric REM re programmed from ELECTRIC REM by Dwyer and Critchfield REM Basic and the Personal Computer Addison Wesley 1978 REM provides a pictorial representation of the REM resultant electrical field around charged points DIM a 10 b 10 c 10 DIM x y i j INTEGER xscale 50 78 yscale 50 32 INPUT How many charges do you have n PRINT The field of view is 0 50 0 50 x y FOR i 1 TO n PRINT type in the x and y positions of charge PRINT i INPUT a i b i NEXT i PRINT type in the size of each charge FOR i 1 TO n PRINT charge i INPUT c i NEXT i REM visit each screen position FOR y 32 TO 0 STEP 1 FOR x 0 TO 78 REM compute field strength into v GOSUB 10 Z v 50 REM map z to valid ASCII in b GOSUB 20 REM print char proportional to field PRINT b NEXT x PRINT EXT y D hel continued on next page A 6 Appendix A Sample Programs electric continued 10 ved FOR i 1 TO n r SQRT SQ xscale x a i SQ yscale y b i EXITIF r 0 THEN v 99999 ENDEXI v i vtc i r NEXT i RETURN 20 IF z 32 THEN b iSE IF z gt 57 THEN z z 8 ENDIF IF z gt 90 THEN
16. 24 4 7 28 32 l 5 5 2 10 Sok 3 15 30 7 35 i 40 l 6 6 2 12 6 3 18 36 E T A2 DE 48 7 7 2s 21 42 7 7 49 xs 56 8 2 16 8 3 24 48 i 56 8 64 2 3 27 54 63 8 72 12 27 16 36 20 45 24 54 28 63 32 72 36 81 Chapter 2 Getting Started The table looks pretty good now but it needs a header To add the header re enter edit mode and display the procedure B e mtable PROCEDURE mtable 0000 DIM a b INTEGER EA 0000 DIM a b INTEGER 0012 a 1 0020 PRINT 0024 WHILE a 10 DO 003A b 1 0048 WHILE b lt 10 DO 005E PRINT a b a b TAB MOD b 5 13 0098 IF POS gt 55 THEN PRINT 00BO ENDIF 00B4 b b 1 00C8 ENDWHILE OOCE PRINT 00D6 a a t1 OOEA ENDWHILE 00F0 END Now move the edit pointer to the first PRINT statement and insert a line to print a header I 2 0020 mi 0046 mi print tab 13 PRINT Multiplication Tables PRINT Important Instead of using the lt num gt command you could enter a carriage return twice If you list your program again the new line is now the third line of your procedure Esl 0000 DIM a b INTEGER 0012 a 1 0020 PRINT TAB 13 Multiplication Tables 0046 PRINT 004A WHILE a 10 DO 0060 b 1 0116 E
17. 6 1 Chapter 6 Edit Mode How the Editor Works 6 2 BASIC programs are always stored in memory in a compiled form called I code short for Intermediate Code I code is a complex binary coding system for programs that lies between your original source program and the computer s native machine language I code is relatively compact can be executed rapidly and most importantly can be reconstructed almost back to the original source program The editor is closely connected to the compiler and decompiler systems within BASIC that translate source code to I Code and vice versa When you enter or change a program line and press the return key the compiler instantly translates this text to the internal I code form When BASIC displays program lines it uses the decompiler to translate the I code back to the original source format These processes are completely automatic and do not require any special action on your part This technique has several advantages It allows the text editor to report many syntax errors immediately so you can correct them instantly The I code representation of a program is more compact by about 30 than its original form This allows you to have larger programs in any given amount of available memory When BASIC lists programs they may appear slightly different than the way they were originally typed in but they are always functionally identical to the original form A different appearance ca
18. Copyright and Revision History Disclaimer Reproduction Notice Trademarks Copyright 1991 Microware Systems Corporation All Rights Reserved Reproduction of this document in part or whole by any means electrical mechanical magnetic optical chemical manual or otherwise is prohib ited without written permission from Microware Systems Corporation This manual reflects Version 2 4 of Microware BASIC Version 2 4 of Microware BASIC is to be used with Version 2 4 or greater of the OS 9 operating system Revision G Publication Date January 1991 Publication Editor Walden Miller Ellen Grant Product Number BAS 68 NA 68 MO The information contained herein is believed to be accurate as of the date of publication However Microware will not be liable for any damages including indirect or consequential from use of the OS 9 operating system Microware provided software or reliance on the accuracy of this documentation The information contained herein is subject to change without notice The software described in this document is intended to be used on a single computer system Microware expressly prohibits any reproduction of the software on tape disk or any other medium except for backup purposes Distribution of this software in part or whole to any other party or on any other system may constitute copyright infringements and misappropriation of trade secrets and confidential processes which are the property of Micro
19. The LET statement has the following syntax LET lt variable gt lt value or constant gt For example if you have the following command in your procedure x equals one LET x 1 You could also enter the following LET x 1 2 5 Chapter 2 Getting Started You can also use an implied statement Implied statements have the following syntax lt variable gt lt value or constant gt For example if you have the following command in your procedure y equals ten y 10 You could also enter the following y 10 Naming Variables Reserved Words Variable names may be of any length but you will probably want to keep them short This is a legal variable is legal but tedious to type Variable names must conform to the following rules Names must begin with either an underscore or letter Names cannot contain embedded blanks or dollar signs Names can end in a dollar sign Names can contain any alphanumeric or underscores Names may not be any BASIC reserved word 2 6 Chapter 2 Getting Started BASIC recognizes certain words as reserved They cannot be used as variable names These reserved words are all commands and key words used within BASIC statements Table 2 A BASIC Reserved Words ABS TAGS ADDR AND ASC ASN ATN BASE BOOLEAN BYE BYTE CHAIN CHD CHR CHX CLOSE COS CREATE DATA DATE D
20. dress 4 um dress 4 um as binary FOR i 7 TO 0 STEP 1 IF n lt 0 THEN PRINT 1 PRINT 0 Eri iw H ial A 9 Appendix A Sample Programs PROCEDURE qsortl REM quicksort by T F Ritter PARAM bot top d 1000 INTEGER DIM n m INTEGER btemp BOOLEAN n bot m top LOOP REM each element gets the once over REPEAT REM this is a post inc instruction btemp d n d top n n 1 UNTIL NOT btemp n n 1 REM point at the tested element EXITIF n m THE ENDEXIT REPEAT REM this is a post dec instruction m m 1 UNTIL d m lt d top OR m n EXITIF n m THE ENDEXIT RUN exchange d m d n n n l REM prepare for post inc EXITIF n m THEN ENDEXIT Eri Z DLOOP IF n lt gt top THEN IF d n lt gt d top THEN RUN exchange d n d top ENDIF ENDIF IF bot n 1 THEN RUN qsortl bot n 1 d DIF Eri zZ IF n 1 lt top THEN RUN qsort1 n 1 top d DIF ra z hel ND continued on next page A 10 Appendix A Sample Programs qsortl continued PRO E D t a b hel PRO D D F hel PRO ODD DW F hel CEDURE exchange ARAM a b INTEGER IM temp INTEGER emp a b temp ND CEDURE prin
21. ASN BYE CHR CREATE DELETE DO ENDIF ERR EXP FOR IF KILL LET LOOP MOD OPEN PEEK PRINT READ RESTORE RUN SIN SQRT STRING THEN TRON UPDATE WRITE BASE 1 CHX DEG END ENDWHILE FOR TO GOTO LET GOTO PARAM PUT REPEAT SEEK TRON WRITE ADDR ATN BYTE CHX DATA DIM ELSE ENDLOOP ERROR FALSE GET INPUT LAND LNOT LOR NEXT OR PI PROCEDURE REAL RETURN SEEK SIZE STEP SUBSTR TO TRUE USING XOR BYE CLOSE DELETE ENDEXIT ERROR STEP IF THEN LOOP ON GOSUB PAUSE RAD RESTORE SHELL TYPE AND BASE CHAIN CLOSE DATE DIGITS END ENDWHILE EXEC FIX GOSUB INT LEFT LOG LXOR NOT PARAM POKE PUT REM RIGHT SGN SQ STOP TAB TRIM TYPE VAL CHAIN CREATE DIM ENDIF EXITIF THE GET INPUT NEXT ON GOTO POKE READ RETURN STOP UNTIL Transcendental Functions Numeric Functions String Functions Miscellaneous Functions Operator Precedence ACS x EXP x SIN x ABS x LAND m n MOD m n SQR x ASC char str m LEN str ADDR var FILSIZ lt path gt SIZE var highest lowest ASN x LOG x TAN x FIX x Appendix B Quick Reference LNOT m n RND x SQRT x CHR m MID str m n SUBSTR st1 st2 TRIM str EOF path INKEY lt path gt TAB m ATN x COS x LOGIO x PI FLOAT m INT x LOR m n LXOR m n SGN x SQ x DATES LEFT RIGHTS str m STR x VAL str E
22. BASIC creates user defined data types A user defined data type may consist of any of combination of the five basic data types arrays and other user defined data types For example YPE rec street STRING 30 cityst STRING 30 zip STRING 9 YPE ENTRY name STRING 30 phone STRING 20 address rec DIM Phonebook 80 ENTRY This example is functionally the same array as in Addphone However it is smaller and easier to access By labeling each field with a descriptive name there is no doubt as to what is stored there Each field within an element is referred to by the array name and the number of the element followed by a period followed by the field name or names each separated by a period Phonebook 32 address zip 50311 Once you have defined and accessed variable length records you need to save them for future use The current Addphone program only holds the memory of the phone number while it is running To save the input information you must open an external file You can then place information in this external file OS 9 supports two types of files Sequential files hold records containing ASCII characters There can be any number of characters within a record There can be any number of records in a file within the limits of your disk Records are separated by a carriage return Random access files contain records that store data in the same manner as BASIC in binary There are no
23. DIM value svalu i INTEGER DIM char subs STRING amp char MDCLXVI subs CCXXII DATA 1000 100 500 100 100 10 50 10 10 1 5 1 1 0 FOR i 1 TO 7 READ value READ svalu WHILE x gt value DO PRINT MIDS char i 1 x x value ENDWHILE IF x value svalu THEN PRINT MID subs i 1 MIDS char i 1 x x value tsvalu NDIF E A 4 Appendix A Sample Programs PROCEDURE eightqueens REM originally by N Wirth here re coded from Pascal REM finds the arrangements by which eight queens REM can be placed on a chess board without conflict DIM n k x 8 INTEGER DIM col 8 up 15 down 15 BOOLEAN BASE 0 Iz initialize empty board n 0 FOR k 0 TO 7 Ncol k FOR k 0 TO 14 Nup k RUN generate n x col up down ND RUE NEXT k RUE down k TRUE NEXT k rs PROCEDURE generate PARAM n x 8 INTEGER PARAM col 8 up 15 down 15 BOOLEAN DIM h k INTEGER h 0 BASE 0 s REPEAT IF col h AND up n h 7 AND down n h THEN set queen on square n h x n h col h FALSE up n h 7 FALSE down nth FALSI n nt 1 IF n 8 THEN fl board full print configuration FOR k 0 TO 7 PRINT x k idi NEXT k PRINT ELSE RUN generate n x col up down ENDIF
24. This is generally used in the same way that a RUN statement inside a procedure calls another procedure The only restriction is that all parameters must be constants or expressions without variables See the PARAM statement description The procedure called can be normal or packed If the procedure is not found inside BASIC s workspace BASIC calls OS 9 to attempt to LINK to an external outside the workspace module If this fails BASIC attempts to LOAD the procedure from a file of the same name Examples RUN getdata RUN invert the string to be inverted RUN power 12 354 06 RUN power 32 sin pi 2 SAVE SAVE Chapter 5 System Mode Write Procedure to an Output File Syntax SAVE lt procname gt lt procname gt gt lt pathlist gt SAVE lt pathlist gt Function SAVE writes the procedure s or all procedures with SAVE to an output file or device in source format SAVE is similar to the LIST command except the output is not formatted and I code addresses are not included If a pathlist is not specified it defaults to the name of the first procedure listed If a file of the same name already exists SAVE prompts with the following rewrite You may answer Y for yes which causes the existing file to be rewritten with the new procedure s or N to cancel the SAVE command Important If an asterisk is used the file name lt pathlist gt follows immediately without a greater t
25. and easier to read The line number oriented commands are Command Description space lt line gt text Inserts or replaces a numbered line lt line gt cr Finds a numbered line r Renumbers a line r Renumbers all lines To enter or replace a numbered line enter a space followed by the line number and statement You can enter numbered lines in any order but they are stored in ascending sequence To move the edit pointer to a numbered line type the line number followed by a carriage return The editor moves to that line or the line with the next higher number if the specified number is not found and displays it You can delete the line with the d command The r renumber command uniformly resequences all numbered lines and lines that refer to numbered lines The syntax for this command is as follows r beg line gt lt incr gt CR r beg line gt lt incr gt CR The first format renumbers the program starting at the current line and moving forward to the end of the procedure Lines are renumbered using beg line gt as the initial line number lt incr gt is added to the previous line number for the next line s number The following example gives the first line number 200 the second 205 etc If beg line gt and or lt incr gt are not specified the values 100 and 10 respectively are assumed r 200 5 The second form of the command renumbers all lines in
26. c BYTE TYPE junk 2d 3 STRING 3 e BOOLEAN TYPE crap f BYTE g demo h BYTE i junk 26 If you are ever in doubt of the size of a data structure you can use the function SIZE lt name gt lt name gt is the name of the variable array or structure The size is returned as the number of bytes of the structure Files and Unified Input Output Files and Unified Input Output Hardware input output I O devices used by OS 9 also work like files You can generally use any I O facility regardless of whether you are working with disk files or I O devices such as printers This single interface is standard for any device Simple communication facilities allow any device to be used with any other device This concept is known as unified I O Important Unified I O can benefit routine programming For example file operations can be debugged by communicating with a terminal or printer instead of a storage device and procedures which normally communicate with a terminal can be tested with data coming from and sent to a storage device BASIC normally works with two types of files sequential files random access files A sequential file sends or receives textual data only in the order it is received Once you have accessed a number of bytes you cannot generally start over at the beginning of a sequential file Many I O devices such as printers are necessarily sequential A sequential file contains only
27. how to obtain program optimization when executing your procedures Introduction Getting Started Overview This manual is designed for two purposes to help new Microware BASIC users become comfortable with programming in BASIC to serve as a reference for new and existing users In order to do this this manual is divided into two sections The first section is a user manual that explains how to create a program with BASIC and how to use BASIC s functions to make your programs better The second section is a reference manual Before using Microware BASIC you should be familiar with OS 9 You should be familiar with either the Using Personal OS 9 manual or the Using Professional OS 9 manual These manuals provide an understanding of how OS 9 stores files as well as other useful information When you start your computer or log in to your account the OS 9 prompt is displayed This manual uses a dollar sign to represent the OS 9 prompt To enter the BASIC environment type basic at the prompt and press the Return key OS9 responds by printing basic Copyright 1984 by Microware Reproduced under licens Microware Basic V2 4 Ready B Important If you are not running version 2 4 of BASIC the version number will be different Chapter 1 Overview The 8 prompt indicates that you are in BASIC s system mode Microware BASIC has four modes Mode Description System Mode Used f
28. if you attempt to change no to yes and the word normal occurs before the no you are looking for normal will change to yesrmal Examples c xval yval c GOSUB 5300 GOSUB 5500 Running Programs Chapter Execution Mode To run a BASIC procedure enter RUN lt procname gt If the procedure you want to run was the last procedure edited listed saved etc you can execute it without specifying a procedure name the asterisk shown in the DIR command identifies this procedure If the procedure expects parameters you can enter them on the same command line They must all be constant numbers or strings as appropriate and must be given in the correct order For example RUN add 4 7 This calls a program such as the one that follows and passes it the specified parameters PROCEDURE add PARAMETER a ba b receive the values 4 7 PRINT a b END The ability to pass parameters to a program allows you to specifically initialize program variables Sometimes certain procedures are parts of a larger software system and are designed to be called from other procedures You can use this feature to individually test such procedures by passing them test values as parameters When you execute the RUN statement BASIC enters execution mode The procedure runs until one of the following events occur an END or STOP statement is executed you type Ctr1 E a run time error occurs you type Ct
29. index 1 NEXT index fix the ends list 0 ptr back list 99 ptr fwd ll Oo o Ko Print the list index 0 REPEAT PRINT list index info index list index ptr fwd UNTIL index 0 END Declare Variables Arrays Etc Syntax PARAM var lt var gt type lt var gt lt var gt lt type gt Function PARAM is almost identical to the DIM statement but it does not create variable storage Instead it describes what parameters the called procedure expects to receive from the calling procedure You must insure that the total size of each parameter conforms to the amount of storage expected for each parameter in the called procedure as specified by the PARAM statement 11 29 Chapter 11 Program Statements and Structure TYPE 11 30 BASIC checks the size of each parameter but it does not check the type You should ensure that the parameters evaluated in the RUN statement and sent to the called procedure agree exactly with the PARAM statement specification with respect to the number of parameters their order size shape and type Because type checking is not performed if you understand how the system operates you can make the parameter passing operation perform useful but normally illegal type conversions of identically sized data structures For example passing a string of 80 characters to a procedure expecting a BYTE array having 80 elements assi
30. loop counter variable it uses a special integer version of the FOR NEXT loop This is much faster than the REAL type version and is generally preferable Other kinds of loops also run faster if INTEGER type variables are used for loop counters When writing program loops remember that statements inside the loop may be executed many times for each single execution outside the loop Thus any value which can be computed before entering a loop increases program speed Optimum Use of Arrays and Data Structures The PACK Command Eliminating Constant Expressions and Sub Expressions Fast Input and Output Functions Chapter 4 Program Optimization BASIC internally uses INTEGER numbers to index arrays and complex data structures If the program uses subscripts that are REAL type variables or expressions BASIC converts them to INTEGER before they can be used This takes additional time so use INTEGER expressions for subscripts whenever you can Important The assignment statement LET can copy identically sized data structures LET is much faster than copying arrays or structures element by element inside a loop The PACK command produces a compressed version of a BASIC procedure Depending on the number of comments line numbers etc programs execute from 10 to 30 faster after being packed Minimizing use of line numbers will even speed up procedures that are unpacked Consider the expression X x SQRT 100 2 It
31. lt num gt lt 0 use ABS lt num gt as new random number seed Chapter 10 Expressions Operators and Functions The following functions return results of type INTEGER or BYTE Name Description FIX lt num gt Rounds REAL lt num gt and converts to type INTEGER MOD lt num1 gt lt num2 gt Modulus remainder function MOD returns the remainder of lt num1 gt divided by lt num2 gt If lt num1 gt is negative the result is negative Examples MOD 9 5 4 MOD 11 3 2 ADDR lt name gt Absolute memory address of variable array or structure named lt name gt SIZE lt name gt Storage size in bytes of variable array or structure named lt name gt ERR Error code of most recent error automatically resets to zero when referenced PEEK lt int gt Value of byte at memory address lt int gt WARNING The specified memory address must be within the limits of accessible memory space PEEK 1 gives a bus error on most systems This causes BASIC to abort POS Current character position of PRINT buffer ASC lt str gt Numeric value of first character of str LEN lt str gt Length of string lt str gt SUBSTR lt str1 gt lt str2 gt Substring search returns starting position of first occurrence of str1 in lt str2 gt or 0 if not found INKEY 4 num Returns the number of characters in data buffer FILSIZ num Returns size of a file
32. same position The abbreviations and symbols used in the syntax specifications are Symbol Description Syntax wo Bralfedwidh l w 25 f Fraction field 1 lt w lt 9 j OPTIONAL justification lt left gt right center Chapter 12 Files and Unified Input O utput Real Format Syntax Rw fj Function Real format can be used for numbers of types REAL INTEGER or BYTE The total field width specification must include two overhead positions for the sign and decimal point The f specifies how many fractional digits to the right of the decimal point to display If the number has more significant digits than the field allows the undisplayed places are used to round the displayed digits For example PRINT USING R8 2 12 349 Output 12 395 The justification modes are Mode Description Leftjust y with leading sign and trailing spaces defaultif justification mode omitted gt Right justify with leading spaces and sign i Right justify with leading spaces and trailing sign financial format Example PROCEDURE printdemo PRINT USING R8 2 5678 123 PRINT USING R8 2 12 3 PRINT USING R8 2 555 9 PRINT USING 10 2 6722 4599 PRINT USING R5 1 9999999 END RUN printdemo 5678 12 12 30 555 90 6722 46 kckoAk 12 19 Chapter 12 Files and Unified Input O utput Exponential Format 12 20 Syntax Ew fj Function
33. so it is difficult to know the address of any particular record in the file Examples SEEK fileone filptr 2 SEEK outfile 208894 SEEK inventory part num 1 SIZE inv_rcd READ Chapter 12 Files and Unified Input O utput Read Data Syntax READ lt path num input list Function READ reads input data in ASCII character format from a file or device The lt path num may be an expression which specifies a path number The path number must have been previously opened by OPEN or CREATE in READ or UPDATE access mode except the standard input path 0 Data is read starting at the path s current file pointer address which is updated as data is read READ calls OS 9 to read a variable length ASCII record Individual data items within the record are converted to BASIC s internal binary format These results are assigned in order to the variables specified in the input list The input data must match the number and type of the variables in the input list The individual data items in the input record are separated by ASCII null characters Numeric items can also be delimited by commas or space characters The input record is terminated by a carriage return character Important READ is also used to read lists of expressions in the program See the DATA statement section for details Examples READ inpath name address city state zip PRINT 1 height
34. the following syntax notation is used Notation Description I Items in brackets are optional Items in braces can be optionally repeated ocname A procedure name his An 05 9 file name number TA decimal or hex number how to use the edit mode the editor to create or modify BASIC procedures how to run a BASIC procedure symbolic debugging of programs data types and data structures expressions operators and functions BASIC program statements and structure files and unified input output System Mode Commands System Mode System mode includes commands to save load and examine procedures interact with OS 9 control the workspace environment The following are the system commands BYE CHD CHX DIGITS DIR E EDIT KILL LIST LOAD MEM PACK RENAME RUN SAVE The BASIC command interpreter processes system commands The command interpreter always identifies itself with the B prompt You automatically enter the command interpreter when you start BASIC and when you exit any other mode You can enter commands in either upper or lower case letters Commands such as DIR MEM and BYE do not operate on specific procedures but they may have optional or required parameters Commands such as SAVE LOAD PACK KILL and LIST can operate on a specific procedure or on all procedures within the workspace If the command is used with a specific procedure name the command is app
35. 10 intlist UN prin 1 10 intlist D PROCEDURE prin PARAM a b prin 10 INTEGER DIM c INTEGER FOR c a TO b PRINT prin c EXT c PRINT END PROCEDURE reverse PARAM a b intlist 10 INTEGER DIM c temp 10 INTEGER FOR c b TO a STEP 1 temp b 1 c intlist c EXT c Dm u hel intlist temp END The output should look like this 12345678910 DO 29 82 07 56 574 73 2 1 3 13 Chapter 3 Program Construction Complex Data Types and Subroutines Command Line Parameters 3 14 Parameters may also be passed to the main procedure of a BASIC program A PARAM statement must also appear in the main procedure One major difference between passing parameters between procedures and passing parameters to the main procedure is that parentheses are not required to enclose the parameters passed to the main procedure For example the following two statements pass parameters to a main procedure from the shell filter z myfiles p 1 11 basic makdoc z bman 12 A parameter passed to a procedure is determined to be either a string or numeric argument by the list of parameters given in the PARAM statement The parameters may be expressions that result in the correct data type For example the following statement passes the numeric argument 15 and the string argument thisthat filter 11 44 th
36. DATA TYPE gt lt num gt DIM array name gt lt rows gt lt cols gt lt depth gt The following line declares the matrix array Route with three dimensions of 5 rows 5 columns and 5 depth INTEGER elements Each element is 25 integers DIM Route 5 5 5 INTEGER 25 Like variables you must initialize each array before you use it The following procedure initializes Phonebook to null values PROCEDURE init DIM Phonebook 80 5 STRING 30 DIM x y INTEGER FOR x 1 TO 80 FOR y 1 TO 5 Phonebook x y NEXT y EXT x END wi You should initialize numeric array elements to zero in the same manner Once an array is initialized it can be loaded in various ways The simplest way is to assign individual element s values by an assignment statement which references the specified element Phonebook 1 1 Larry Crane Phonebook 1 2 unlisted Chapter 3 Program Construction Complex Data Types and Subroutines Although this is simple it is extremely time consuming Instead you can use a looping structure and the INPUT statement to load the array PROCE DURE Addphone DI DI DI DAT don XI WHI F N I T Phonebook 80 5 STRING 30 X y INTEGER done BOOLEAN A NAME PHONE ADDRESS CITY STATE ZIP CODE e FALSE 1 LE NOT done AND x lt 80 DO OR y 1 TO 5 READ prompt PRINT ENTER prompt
37. Etc Syntax DIM var lt var gt type lt var gt lt var gt lt type gt Function DIM declares simple variables arrays or complex data structures of the five basic types or any user defined type During compilation BASIC assigns storage required for all variables declared in DIM statements Declaring Simple Variables Simple variables are declared by using the variable name in a DIM statement without a subscript If variables are not explicitly declared they are automatically assumed to be REAL or if the variable name ends with a character STRING 32 Therefore you must explicitly declare all simple variables of other types For example DIM logical BOOLEAN 11 27 Chapter 11 Program Statements and Structure 11 28 You can declare several variables in sequence by separating each variable with a comma DIM a b c STRING In addition you can declare several different types in a single DIM statement by using a semicolon to separate different types DIM a b c INTEGER n m decimal x y z BOOLEAN In this example a b and c are type INTEGER n and m are type decimal a user defined type and x y and z are type BOOLEAN String variables are declared the same way except you can specify an optional maximum string length If a length is not explicitly given 32 characters are assumed DIM name STRING 40 address city STRING zip REAL In this case n
38. Exit Basic Syntax BYE Function BYE exits BASIC and returns to OS 9 or the program that called BASIC Any procedures in the workspace are lost if not previously saved The end of file character usually the escape key does the same thing CHD CHX Change Directories Syntax CHD lt pathlist gt CHX lt pathlist gt Function CHD changes the current OS 9 user data directory to the specified pathlist which must be a directory file BASIC uses the data directory to LOAD or SAVE procedures cHx changes the current OS 9 user execution directory to the specified pathlist which must be a directory file The execution directory is used to PACK or auto load packed modules Example CHD d1 joe games 5 4 DIGITS DIR Chapter 5 System Mode Formats Numerical Output Real Numbers Syntax DIGITS lt number gt Function DIGITS controls the number of digits that are printed when REAL numbers are output DIGITS also controls the precision of transcendental calculation The minimum precision is 1 digit to the right of the decimal point and the maximum precision is 15 If the result is not within this range 1 to 15 precision the result is brought into range without error When no number is specified DIGITS displays the current precision Example PROCEDURE Digitsdemo DIM x REAL DIGITS 2 INPUT x PRINT x END RUN Digitsdemo 44 9234692 44 Display Directory
39. Pd CR A Eg de ee S DIR ess de eoe dee ta dete ues wile oe aa e CE Rs EDIE 4 net daa e baden a d eee a desde e dees KIEE KIDL us use n ER ner nee RR We ARR e ae LEIST EIST ererek REIR RR mme RR ee doh See RR LOAD odes beret Cx ce dnd Aosta dd Ble PR A Uie EROR UR do ded aid MEM pecs cnn Spa o ee sa ques ipsae e sta s e Rs PACK PACK ir aa eh Re mcer XO RE RR GE ex RENAME 42224 RU Roe e SUR SCR o dep deos SAVBE SAVET coss cur ex degree Lane RU KR DI e odpa i adios d gral Edit Mode Chapter 6 Edit Mode Commands 00 00 c cece een nee How the Editor Works lseseseeeeeeee eens Line Number Oriented Editing 000 e eee eee eee String Oriented Editing 0 0 eee eee Execution Mode Chapter 7 Running Programs 0 cece eee een ene eee 7 1 Execution Mode Technically Speaking lessen 7 2 Table of Contents 05 9 BASIC User Manual Debug Mode Chapter 8 CONT act desee eet he Gains cian bd desse neu emet Da Ride DIR uod be nos dmi ise timida ate na ee aed eM o tp RAE Debugging Techniques lseselseeeee e Debug Mode as a Desk Calculator 0 0 0 0 eee eee ee Data Types and Data Chapter 9 Structures Data Types siss nc hes ete RR ee ee ee ee eee ee Y Data Structures c wale dei ded eb epu ER OL e p dated The Five Basic Data Types lssseeeeeee eee The BYTE Data Type ssssseeee IIR The INTEGER Data Type 2 oce
40. Rem shows The REAL Data Type erp Re euh em ee 9 exi pe exe Internal Representation of REAL Numbers The STRING Data Type seseeee II The BOOLEAN Data Type sseeeeeee I Automatic Type Conversion lseeeeleee eee Constants ise xe Gre aded avec Wee ca baee ea eun cius Numeric Constants sseiscsseipierarenen atit n Boolean Constants 0 0 0 cece cece eee ees Stine Constants os cose cea eh eka aaa eee de re awd Variables occ vet ated Boe Re bibs See Sh ia oe RE ee ebd Parameter Variables 0 0 0 0 cece eee eee nuo MC Complex Data Types sese Table of Contents 0S 9 BASIC User Manual Expressions Operators and Chapter 10 Functions Evaluation of Expressions Operators EET EE Operator Precedence 0 0 cece cette eens P nc ols cse9ee eem Cae anna Cae eoe dey Rares a Hae dos Panda Program Statements and Chapter 11 Structure Program Structure dcos isoa e E E e Assignment Statements 0 0 cece cece eee Ip EE PORINEXT 23520 a uel atia ativan SPON voile bs ean WHIEE DO pesos 235 8 dan oeRerbesu sk ac ep ee ec REPEAT UNTIL cere RR dig denies depen a dane eve LOOP ENDLOOP EXITIF ENDEXIT GOTO qr GOSUB RETURN p ub he XR QU ee ee RED RED Dee ON GOTO ON GOSUB 0 00 eee ON ERROR GOTO 0 ees Execution Statements 0 ccc ccc eens ERROR i2isreie ea e RIA es eta bb bee d RI d oe DEGRA D cotta
41. The following functions can return any numeric type depending on the type of the input parameter Name Description ABS num Absolute value of num SGN lt num gt Signum of num 1 if num 0 0 if num 20 or 1 if num 0 SQ num Square num VAL lt str gt Convert type STRING to type NUMERIC 10 5 Chapter 10 Expressions Operators and Functions The following functions perform bit by bit logical operations on integer or byte data types and return integer results Do not confuse them with the BOOLEAN type operators Name Description LAND lt num gt lt num gt Logical AND LOR lt num gt lt num gt Logical OR LXOR lt num gt lt num gt Logical EXCLUSIVE OR LNOT lt num gt Logical NOT These functions return a result of type STRING Name Description CHR lt int gt ASCII character equivalent of int int must be within range of 0 127 DATE Date and time format yy mm dd hh mm ss LEFT lt str gt lt int gt Leftmost lt int gt characters of lt str gt RIGHT lt str gt lt int gt Rightmost lt int gt characters of lt str gt MID lt str gt lt int1 gt lt int2 gt Middle lt int2 gt characters of str starting at character position lt intl gt STR lt num gt Converts numeric type lt num gt to displayable characters of type STRING representing the number converted TRIM lt Str
42. a7 48 bytes of registers blo s ParamErr branch if not EN Now put the model on the stack move w Modllen 2 d2 number of words for dbra lea Model Modllen pc a0 get address of model bra s SysC02 branch into loop SysC0O1 move w a0 a7 move a word SysC02 dbra d2 SysC0O1 continue if not done move 1 d1 a0 point to function code move w 2 a0 2 a7 set function code al Get the registers movea l Param2 Modllen a7 a5 get address of parameter movem l a5 d0 d7 a0 a4 get register jsr a7 call function movem l d0 d7 a0 a4 a5 lea 1 Modllen a7 a7 clear stack rts ParamErr move w ESParam dl get error code ori Carry ccr set carry rts Model os9 FSFork model system call to put on stack rts Modllen equ Model ends A 19 System Mode Commands Edit Mode Commands Debug Mode Commands Quick Reference DIGITS KILL PACK d d space DIR TROFF BYE DIR LIST RENAME BREAK LET RAD TRON Appendix CHD LOAD RUN CI r lt line gt r CONT LIST STATE CHX EDIT MEM SAVE c s DEG PRINT STEP Appendix B Quick Reference Basic Reserved Words Basic Statements B 2 ABS ASC BOOLEAN CHD COS DEG DIR ENDEXIT EOF EXITIF FLOAT GOTO INTEGER LEN LOGIO MID ON PAUSE POS RAD REPEAT RND SHELL SQR STR TAN TROFF UNTIL WHILE BASE 0 CHD DATA ELSE ENDLOOP N GOSUB KILL ON ERROR OPEN PRINT REM RUN TROFF WHILE DO ACS
43. as a single entity for example PUT 2 employee_file Arrays or complex structures may be elements of subsequent complex structures or arrays Evaluation of Expressions Expressions Operators and Functions Many BASIC statements evaluate expressions The result of an evaluation is always a value of some basic type REAL INTEGER STRING or BOOLEAN The expression itself may consist of values and operators For example the expression 5 5 results in an integer with a value of ten A value can be a constant value a variable name or a function which returns the result as a value An operator combines values typically those adjacent to the operator and also returns a result When evaluating an expression each value is copied to an expression stack where functions and operators take their input values and return results If the expression is used in an assignment statement the assignment is made only when the result of the entire expression has been This allows the variable which is being modified to be one of the values in the expression The same principles apply for numeric string and boolean operators These principles make assignment statements such as X X 1 legal in all cases even though it would not make sense in a mathematical context Any expression evaluates to one of the five basic data types This does not mean however that all the operators and operands in expressions have to be of an identical type Often ty
44. b 2 ELSE IF z gt INT z 5 THEN b SE b CHR z ENDIF ENDIF A 7 Appendix A Sample Programs PROCEDURE structst REM example of intermixed array and record structures REM note that structure d contains 200 real elements YPE a one 2 REAL b two 10 a c three 10 b DIM d e c K go E K tu E FOR i 1 TO 10 FOR j 1 TO 10 FOR k 1 TO 2 PRINT d three i two j one k d three i two j one k 0 PRINT e three i two j one k PRINT NEXT k NEXT j NEXT i amp this is a complete structure assignment e d FOR i 1 TO 10 FOR j 1 TO 10 FOR k 1 TO 2 PRINT e three i two j one k NEXT k PRINT NEXT j EXT i Eri iw A 8 PROCEDURE wordlook Display a wo By Andy Nich aw E Epi DIM address dat PUT Enter wor atum PEEK ad UN prinbyte dat atum PEEK ad UN prinbyte dat atum PEEK ad UN prinbyte dat atum PEEK ad v a woo go UN prinbyte dat D hel lo ve 9 Q EDURE prinbyte a amp print a byte RAM n INTEGER DI i INTEGER as Di n n 16777216 Appendix A Sample P rograms rd at a user specified address olson um INTEGER d address address dress um dress 4 um
45. carriage returns to indicate the end of a record Records must be of a fixed size There may be any number of records in the file within the limits of your disk Chapter 3 Program Construction Complex Data Types and Subroutines Sequential Files Sequential files are generally used for text files because of the way data is accessed To store data in a sequential file BASIC supports two commands READ and WRITE The READ command reads characters from a file until it encounters a carriage return The WRITE command sends each character in the record to the file and then sends a carriage return to indicate the end of record Sequential files must be read one record at a time starting from where the file pointer is positioned Because of the way data is stored in sequential files the only way to position the file pointer is to read or write a record To access the third record of a sequential file you must either read the first two records or rewrite them to place the file pointer at the beginning of the third record If you were to rewrite the first record with a new record that is larger than the original you will also write over the beginning of the second record Obviously this could cause many problems To effectively edit sequential files you must use a text editor word processor etc Random Access Files To store data in a random access file BASIC supports two commands The PUT command puts a record in
46. for both REAL and INTEGER values The INTEGER versions are much faster and may have slightly different properties for example when you divide INTEGER values the remainder is discarded Converting data types takes time so expressions whose operands and operators are of the same type are more efficient INTEGER operations are faster because they generally have corresponding 68000 machine language instructions Overall program speed increases and storage requirements decrease if INTEGERs are used whenever possible INTEGER arithmetic operations use the same symbols as REAL but BASIC automatically selects the INTEGER operations when working with an integer value result Only if all operands of an expression are of types BYTE or INTEGER will the result also be INTEGER Sometimes you can get similar or identical results in a number of different ways at various execution speeds For example if the variable value is an integer value 2 is a fast integer operation However if the expression is value 2 the value 2 is represented as a REAL number and the multiplication is a REAL multiplication which also requires that the variable value must be transformed into a REAL value and finally the result of the expression must be transformed back to an INTEGER value if you assign it to a variable of that type Therefore a single decimal point slows down this operation by about ten times When Basic identifies a FOR NEXT loop structure with an INTEGER
47. is exactly the same as the expression X t x 5 The sub expression SQRT 100 2 consists of constants only so its result does not vary regardless of the rest of the program But every time the program is run the computer must evaluate it This time can be significant especially if the statement is within a loop You should calculate constant expressions or sub expressions while writing the program Reading or writing data a line or record at a time is much faster than one character at a time Also the GET and PUT statements are much faster than READ and WRITE statements when dealing with disk files This is because GET and PUT use the exact binary format used internally by BASIC READ WRITE PRINT and INPUT must perform binary to ASCII or ASCII to binary conversions 4 3 Chapter 4 Program Optimization Professional Programming Techniques 4 4 You can make a program faster by using efficient algorithms You can use algorithms found in most standard BASIC and PASCAL books with little or no adaptation You should use a well structured programming style that produces efficient reliable readable and maintainable software BASIC generates optimized code for the 68000 to execute This code is currently the most powerful 16 bit processor in existence A computer can only execute what it is told to execute No language implementation can make up for an inefficient program An inefficient program is evidence of a lack of und
48. lines in which it is found The edit pointer is moved to the last line where the string occurred Here are some examples Command Description E s counter Looks for the string counter E s 1 2 Looks for the string 1 2 E s three blind mice Looks for the string three blind mice Change STRING Substitution The change string function can eliminate a tremendous amount of typing It allows strings within lines to be located removed and replaced by another string This command is commonly used for fixing error lines without having to retype the entire line or changing a variable name throughout a program The format for the c command is as follows c delim match str lt delim gt repl str lt delim gt CR c delim match str delim repl str delim CR Chapter 6 Edit Mode In the first form the editor looks for the first occurrence of the match string starting at the present edit pointer position If found the match string is removed from the line and the replacement string is inserted in its place The second form works the same way except it changes all occurrences of the match string in the procedure starting at the edit pointer s current position The c command stops when it finds or creates a line with an error Important Sometimes you can inadvertently change a line you did not intend to change because the match string is imbedded in a longer string For example
49. name END DIF 2 25 Introduction Arrays Program Construction Complex Data Types and Subroutines This chapter discusses the following complex data types and subroutines that you can use with Microware BASIC arrays TYPE declarations external files subroutines command line parameters formatted output An array is an ordered sequence of data types An array may be one two or three dimensional A vector is a one dimensional array A table is a two dimensional array A matrix is a three dimensional array The size of an array depends on the number of elements in each dimension and the size of each element The array size is declared with a statement The syntax for declaring a vector array is as follows DIM array name rows DATA TYPE lt num gt For example the following line declares the vector array names Names has 80 string elements Each element is 30 characters DIM Names 80 STRING 30 The syntax for declaring a table array is as follows DIM array name rows cols DATA TYPE lt num gt The following line declares the table array PHONEBOOK with the two dimensions of 80 rows and 5 columns of STRING elements Each element is 30 characters DIM Phonebook 80 5 STRING 30 3 1 Chapter 3 Program Construction Complex Data Types and Subroutines 3 2 The syntax for declaring a matrix array is as follows lt
50. number of the I O path The I O path must have been previously opened by OPEN or CREATE Paths used by PUT statements must have been opened in WRITE or UPDATE access modes and paths used by GET statements must be in READ or UPDATE mode The statement uses exactly one name which can be the name of a variable array or complex data structure Data is written from or read into the variable or structure named The data is transferred in BASIC s internal binary format without conversion This affords high throughput compared to READ and WRITE statements Data is transferred beginning at the current position of the path s file pointer which is automatically updated OS 9 s file system does not inherently impose record structures on random access files All files are considered continuous sequences of addressable binary bytes A byte or group of bytes located anywhere in the file can be read or written in any order Therefore you can use the basic file access system to create any desired record structure Record I O in BASIC is associated with data structures defined by DIM and TYPE cet and PUT write entire data structures or parts of data structures PUT for example can write a simple variable an entire array or a complex data structure in one operation To illustrate how this works the following example is based on a simple inventory system that requires a random access file having 100 records Each record must include the followin
51. occurs In this case it bypasses the problem of recreating an existing file flag TRUE ON ERROR GOTO 100 CREATE file phonebook UPDATE flag FALSE 100 IF flag THEN OPEN file phonebook UPDATE ENDIF Normally when an error occurs the procedure terminates and BASIC changes to debug mode A FALSE value is assigned to flag between the CREATE and IF THEN OPEN structure This assures that only one of the two access statements OPEN or CREATE is executed The ON ERROR without the GOTO effectively turns off the previous ON ERROR statement This is important because any other error that might occur would otherwise be routed to line 100 Because you can use this procedure to both read and write to the phonebook file you must access the file in UPDATE mode By prompting for one of three conditions add access or done you can channel control to any of these conditions By placing this control structure within a REPEAT loop you may add and access entries in the same session By adding REPEAT loops within add and access sections of the code you may add or access as many records as desired The SEEK statement allows access to the records In the add loop the file pointer is moved to the end of file with the following command SEEK file FILSIZ file The SEEK command positions the file pointer directly after the specified number of bytes The FILSIZ function returns the
52. result must be compatible with the corresponding format specification If there are fewer format specifications than items in the output list the format specification list is repeated again from its beginning as many times as necessary A format string has one or more format specifications separated by commas There are two kinds of specifications Those that control output editing of an item from the output list Those that cause an output function by themselves such as tabbing and spacing There are six basic output editing directives Each has a corresponding one letter identifier Name Description R RealFormat E Exponential Format qo 0 Integer Format H Hexadecimal Format S String Format B Boolean Format 12 17 Chapter 12 Files and Unified Input O utput 12 18 The identifier letter is followed by a constant number called the field width This number indicates the exact number of print columns the output is to occupy and must allow for the data and overhead character positions such as sign characters decimal points exponents etc Some formats have additional mandatory or optional parameters that control subfields or select editing options One of these options is justification to specify whether the output is to center or line up the output field on the left or right side Fields are commonly right justified in reports because it arranges them into columns with decimal points aligned in the
53. size of the file specified by its path Consequently by using both together the file pointer is positioned at the end of file In the access loop the SEEK command positions the file pointer at the beginning of the user specified record For simplicity this procedure uses numbers to specify records first record second record etc The BASIC function SIZE returns the size of the specified data structure By multiplying this size by one less than the desired record the file pointer is correctly positioned SEEK file SIZE Phonebook record 1 3 9 Chapter 3 Program Construction Complex Data Types and Subroutines Subroutines 3 10 The phonebook procedure is unnecessarily complex When you repeatedly use a portion of a procedure place it in a subroutine Generally subroutines clarify code or avoid repeating the same code throughout a procedure In the previous program you can place the add and access loops in subroutines to improve clarity The GOSUB statement accesses subroutines The syntax for this structure is as follows GOSUB lt line gt lt line gt subroutine RETURN The GOSUB statement unconditionally passes control to the specified line Basic continues to execute sequentially from that point until the RETURN statement is encountered Control is then returned to the line immediately following the GOSUB statement Basic supports a related statement that provides better us
54. structures and data types Powerful interactive debugging and editing features Integral full featured text editor Syntax error check upon line entry and procedure compile Trace mode reproduces original source statements Renumber command for line numbered procedures Microware Basic was conceived in 1978 as a high performance programming language to demonstrate the capabilities of the 6809 microprocessor to efficiently run high level languages Microware BASIC was developed at the same time as the 6809 under the auspices of the architects of the 6809 It was originally titled Basic09 The project covered almost two years and incorporated the results of research in such areas as interactive compilation fast floating point arithmetic algorithms storage management high level symbolic debugging and structured language design These innovations give Microware BASIC its speed power and unique flavor Microware BASIC was commissioned by Motorola Inc Austin Texas and developed by Microware Systems Corporation Des Moines Iowa Principal designers of Microware BASIC were Larry Crane Robert Doggett Ken Kaplan and Terry Ritter The first release was in February 1980 Excellent feedback thoughtful suggestions and carefully documented bug reports from Microware BASIC users all over the world have been invaluable to the designers in their efforts to achieve the degree of sophistication and reliability Microware BASIC has toda
55. the called procedure The called procedure must have a PARAM statement with variables of the same size and data type as the values passed Parameters may be any type of data structure The syntax for the PARAM statement is as follows PARAM lt declaration sequence gt lt type gt If a parameter is a constant or an expression it is passed by value This means the called procedure can change it but the changes are not returned to the calling procedure If a parameter is a variable array or data structure it is passed by reference This means that any changes made to the value of the parameter are returned to the calling procedure ByTE data types may only be passed by reference Commas separate items in the declaration sequence For example PARAM a b INTEGER You can declare multiple data types on the same line by using semicolons For example PARAM a b INTEGER c d REAL listing 10 BYTE Chapter 3 Program Construction Complex Data Types and Subroutines The following example passes an array of integers by reference Example creates the array and passes it to prin prin prints the array and passes it back to example example passes it to reverse which reverses the order of the array The reversed array is passed back to example prin is run once more to validate the reversal process PROCEDURE example DIM a intlist 10 INTEGER FOR a 1 TO 10 intlist a a EXT a UN prin 1 10 intlist UN reverse 1
56. the file A new file is created on a storage device by executing CREATE Once a file exists the OPEN command sets up a channel to the desired device and returns that path number to the BASIC program This channel number is then used in file access operations READ WRITE GET PUT SEEK etc When you are finished with the file you should close it to assure that the file system has updated all data back on to magnetic media A path is a description of a channel through which data flows to or from a given program or device When a path is created OS 9 returns a unique number to identify the path in subsequent file operations I O statements use this path number to specify the file to use Important In order for data to flow to or from a device there must be an associated OS 9 device driver For detailed information on device drivers consult the OS 9 Technical Manual Three path numbers have special meanings because they are standard I O paths representing BASIC s interactive input output These are automatically opened for you and should not be closed except in special circumstances The standard I O path numbers are Number Description 0 Standard Input Keyboard 1 Standard Output Terminal Display 2 Standard Error Status Terminal Display INPUT Chapter 12 Files and Unified Input O utput The following table summarizes the I O statements within BASIC and their general use This reflects typical use
57. to create an array having five storage spaces called AGES use the statement DIM AGES 5 INTEGER 5 tells BASIC how many spaces to reserve INTEGER indicates the array s data type To assign a value of 22 to the third storage space in the array use the statement LET AGES 3 22 9 1 Chapter 9 Data Types and Data Structures The Five Basic Data Types The BYTE Data Type 9 2 BASIC includes five basic data types Type Allowable values Memory requirement BYTE 5 Whole Numbers 0 to 255 One byte INTEGER Whole Numbers 2 147 483 648 to 2 147 483 647 Four bytes REAL Floating Point 4 2 2 10 308 to 1 8 10 308 Eight bytes STRING Letters digits punctuation One byte character BOOLEAN True or False One byte REAL numbers appear to be the most versatile data type They have the greatest range and are floating point Arithmetic operations involving them however are relatively slow by a factor directly related to the memory required when compared to the INTEGER or BYTE types Therefore using INTEGER values for loop counters indexing arrays etc can significantly speed up your programs While the BYTE type is not appreciably faster than INTEGER it conserves memory space in some cases and serves as a building block for complex data types in other cases If you neglect to specify the type of a variable BASIC automatically assumes the REAL data ty
58. Buffer loc buffer LOOP INPUT change sector offset rewrite EXITIF rewrite THEN RUN DumpBuffer loc buffer ENDEXIT EXITIF rewrite S OR rewrite s THEN ENDEXIT offset VAL rewrite 1 LOOP EXITIF offset gt 256 THEN ENDEXIT modloc loctoffset 1 PRINT USING h4 h2 modloc buffer offset INPUT rewrite Gl EXITIF rewrite THEN ENDEXIT IF rewrite lt gt THEN buffer offset VAL rewrite ENDIF offset offsettl NDLOOP ENDLOOP INPUT rewrite sector rewrite IF LEFTS rewrite 1 Y OR LEFTS rewrite 1 y THEN SEEK path loc PUT path buffer ENDIF NDLOOP CLOSE path BYE s I s continued on next page Appendix A Sample Programs patch continued PROCEDURE DumpBuffer Called by PATCH TYPE buffer char 4 INTEGER PARAM loc REAL line 16 buffer DIM i j INTEGER WHILE loc gt 65535 DO loc loc 65536 NDWHILE FOR j 1 TO 16 N PRINT USING h4 FIX INT loc j 1 16 PRINT FOR i 1 TO 4 PRINT USING X1 H8 line j char i NEXT i RUN printascii line j PRINT EXT j PROCEDURE PrintASCII TYPE buffer char 16 BYTE PARAM line buffer DIM as
59. EAN flag TRUE ON ERROR GOTO 100 CREATE file phonebook UPDATE flag FALSE 100 IF flag THEN OPEN file phonebook UPDATE ENDIF ON ERROR REPEAT PRINT Would you like to add or access entries PRINT Or are you finished for now INPUT Type add access or done answer IF answer add THEN SEEK file FILSIZ file PRINT If information not available hit return REPEA INPUT name Phonebook name INPUT phone number Phonebook phone INPUT street address Phonebook address street INPUT city state Phonebook address cityst INPUT zip code Phonebook address zip PUT file Phonebook PRINT If finished type done INPUT Otherwise hit the return done UNTIL done done ELSE IF answer access THEN REPEAT INPUT What number record would you like record SEEK file SIZE Phonebook record 1 GET file Phonebook PRINT name Phonebook name PRINT phone number Phonebook phone PRINT street address Phonebook address street PRINT city state Phonebook address cityst PRINT zip code Phonebook address zip PRINT If finished type done INPUT Otherwise hit the return done UNTIL done done ENDIF ENDIF UNTIL answer done CLOSE file 3 8 Chapter 3 Program Construction Complex Data Types and Subroutines Important The BASIC statement ON ERROR GOTO gives control to the specified line if an error
60. EG DELETE DIM DIGITS DIR DO ELSE END ENDEXIT ENDIF ENDLOOP ENDWHILE EOF ERR ERROR EXEC EXITIF EXP FALSE FILSIZ FIX FLOAT FOR GET GOSUB GOTO IF INKEY INPUT INT INTEGER KILL LAND LEFT LEN LET LNOT LOG LOG10 LOR LOOP LXOR MID MOD NEXT NOT ON OPEN OR PARAM PAUSE PEEK P POKE POS PRINT PROCEDURE PUT RAD READ REAL REM REPEAT RESTORE RETURN RIGHT RND RUN SEEK SGN SHELL SIN SIZE SQ SQR SQRT STEP STOP STR STRING SUBSTR TAB TAN THEN TO TRIM TROFF TRON TRUE TYPE UNTIL UPDATE USING VAL WHILE WRITE XOR 2 7 Chapter 2 Getting Started Variable Data Types BASIC recognizes five data types Type Description INTEGER Whole numbers no decimal ranging from 2 147 483 648 to 2 147 483 647 REAL Floating point numbers decimal point allowed ranging from 2 2 10 308 to 1 8 10 308 BYTE Whole numbers no decimal ranging from 0 to 255 STRING Letters digits and or punctuation BOOLEAN True or False Important Numbers may be INTEGER REAL or BYTE values While REAL numbers are the most versatile that is they have the greatest range and can represent decimals math operations involving them are relatively slow INTEGER and BYTE operations use less memory and are executed faster A STRING is a variable length sequence of characters An empty STRING is a special case and contains no characters A STRING may be declared to have a specified length by using the DIM statement This is useful fo
61. Examples REM this is a comment This is also a comment This is another kind of comment 11 26 Declaration Statements DIM Chapter 11 Program Statements and Structure The DIM PARAM and TYPE statements are called declaration statements because they define and or declare variables arrays and complex data structures DIM and PARAM are almost identical the difference being that DIM declares storage used exclusively within the procedure and PARAM declares variables received from another calling procedure You do not need to use DIM for simple variables of type REAL because this is the default format for undeclared variables You also do not need to use DIM for 32 character STRING type variables any name ending with a is automatically assigned this type Even though you do not have to declare variables in these two cases using DIM improves your program s internal documentation The things you must declare are any simple variables of type BYTE INTEGER or BOOLEAN any simple STRING variables shorter or longer than 32 characters arrays of any type complex data structures of any type The TYPE statement does not really create variable storage Instead it describes a new data structure type that can be used in DIM or PARAM statements in addition to the five basic data types built in to BASIC Therefore TYPE is only used in programs that use complex data structures Declare Variables Arrays
62. G 24 name p OPEN printer_path name WRITE PRINT printer_path Mary had a little lamb CLOSE printer_path DIM inpath INTEGER dev winchester INPUT name OPEN f inpath devS name READ OPEN path userdir READ DIR OPEN path name WRITE EXEC CREATE Chapter 12 Files and Unified Input O utput Create a New File Syntax CREATE lt path num pathlist access mode Function CREATE creates a new file on a multifile mass storage device such as disk or tape If the device is not of multifile type CREATE works like an OPEN statement The path number may be a variable The variable name receives the path number OS 9 assigned The variable must be of BYTE or INTEGER type The pathlist must be within quotes A string variable is allowed and is evaluated and passed to OS 9 as the descriptive pathlist The access mode defines the direction of subsequent I O transfers and should be either WRITE or UPDATE UPDATE mode allows the file to be either read or written OS 9 has a single file type that can be accessed either sequentially or at random Files are byte addressed so no explicit record length need be given see GET and PUT statements When a new file is created it has an initial length of zero Files are expanded automatically by PRINT WRITE or PUT statements that write beyond the current end of file Examples
63. IC that there is more to print on the same line When a PRINT statement contains multiple values it prints the values consecutively You must separate each of these values by a comma or a semicolon If the separator is a comma BASIC moves to the next 16 column tab stop before printing the next value If the separator is a semicolon no space separates the fields Important If you do not want to use the default tab stops refer to the description of the TAB command located in the command summary The END statement is optional It tells BASIC to stop executing the procedure and return to system mode BASIC returns to system mode after executing the last line of code within the procedure To list your procedure type I This edit mode command lists the procedure PROCE DURE myprogram 0000 0012 0017 0035 PRINT type your name INPUT name PRINT Hi name It s been nice talking to you END Chapter 2 Getting Started The DIM Statement Declaring Variables 2 4 Important The editor has added some information which you did not type The numbers to the left of the program are I code addresses These are the actual memory locations where each line begins relative to the start of the procedure These numbers may appear strange because they are in hexadecimal base 16 The I code addresses are important because when BASIC finds an error in a procedure it conveys as much information as it
64. ILE DO structure 9 9 11 274 11 30 TYPE U unified I O UPDATE 3 6 3 7 variables 9 7 assigning values 9 6 data types declaring declaring simple initializing naming 2 7 printing value vector 3 1 9 9 11 30 W WHILE DO workspace defined 1 2 deleting procedures in 1 2 1 4 displaying procedures i listing procedures in 1 2 1 3 loading procedures in requ WRITE 3 5 access modes WRITE 3 7 ALLEN BRADLEY WU 394 ROCKWELL INTERNATIONAL COMPANY With offices in major cities worldwide WORLD EUROPE MIDDLE HEADQUARTERS EAST AFRICA Allen Bradley HEADQUARTERS 1201 South Second Street Allen Bradley Europa B V Milwaukee WI 53204 USA Amsterdamseweg 15 Tel 414 382 2000 1422 AC Uithoorn Telex 43 11 016 The Netherlands FAX 414 382 4444 Tel 31 2975 60611 Telex 844 18042 FAX 31 2975 60222 Publication 1771 6 5 103 September 1992 As a subsidiary of Rockwell International one of the world s largest technology companies Allen Bradley meets today s challenges of industrial automation with over 85 years of practical plant floor experience More than 13 000 employees throughout the world design manufacture and apply a wide range of control and automation products and supporting services to help our customers continuously improve quality productivity and time to market These products and services not only control individual machines but integr
65. INPUT Phonebook x y EXT y NPUT If finished type done otherwise lt return gt flag F flag done THEN done TRUE ELSE m x Xx 1 ENDIF END WHILE END In this procedure the DATA and READ statements are used The READ statement reads sequentially from the DATA statements output list When the list is exhausted it starts reading from the beginning of the list again In this case Addphone uses the READ statement to change prompts for each element of the array For more information on the DATA and READ statements refer to the appropriate reference section Notice the INPUT statement following the FOR NEXT structure INPUT If finished type done otherwise return flag This INPUT statement prints out the character string instead of the regular question mark prompt This eliminates an extra PRINT statement Chapter 3 Program Construction Complex Data Types and Subroutines The TYPE Declaration External Files 3 4 While the Addphone procedure is adequate for storing names and phone numbers an array of varying data types and sizes is more efficient In the Phonebook array each element is thirty characters long regardless of the use of the field A phone number field rarely needs to be greater than twenty digits A zip code can be held in nine By using the TYPE declaration
66. Important Transcendental functions take a long time to return a value if passed an extremely large value for example SIN 100000000 Name Description SIN lt num gt Trigonometric sine of num Result 1 lt SIN lt num gt lt 1 C0S lt num gt Trigonometric cosine of num Result 1 lt COS num lt 1 TAN lt num gt Trigonometric tangent of lt num gt ASN lt num gt Trigonometric arcsine of num Result PI 2 lt ASN lt num gt lt P1 2 ACS lt num gt Trigonometric arcosine of num Result 0 lt ACS lt num gt lt PI ATN lt num gt Trigonometric arctangent of num Result P 1 2 lt ATN lt num gt lt P 1 2 LOG lt num gt Natural logarithm base e of lt num gt which must be positive LOG10 lt num gt Logarithm base 10 of num which must be positive SQR num Square root of num which must be positive SQRT lt num gt Square root of lt num gt same as SQR EXP lt num gt e 2 71828183 raised to the power num which must be a positive number FLOAT num num converted to type REAL from BYTE or INTEGER INT lt num gt Truncates all digits to the right of the decimal point of a REAL lt num gt Examples INT 0 21 2 0 INT 2 5 2 PI The constant 3 141592653589793 RND num If lt num gt 0 returns random x 0 2x 1 If lt num gt gt 0 returns random x 0 lt x lt num If
67. MERIC I Division UMERIC UMERIC Addition UMERIC UMERIC Subtraction UMERIC UMERIC NOT Logical Negation BOOLEAN BOOLEA AND Logical AND BOOLEAN BOOLEA OR Logical OR BOOLEAN BOOLEA XOR Logical EXCLUSIVE OR BOOLEAN BOOLEA Concatenation STRING STRING Equal to ANY BOOLEA lt gt 0r gt lt Not equal to ANY BOOLEA lt Less than NUMERIC STRING 1 BOOLEA lt 0r lt Less than or Equal NUMERIC STRING 2 BOOLEA gt Greater than NUMERIC STRING 3 BOOLEA gt 0r gt Greater than or E qual NUMERIC STRING 4 BOOLEA When comparing strings the ASCII collating sequence is used so that 0 lt 1 lt 9 A lt B lt Z a b z Important NUMERIC refers to either BYTE INTEGER or REAL types Chapter 2 Getting Started Conditional Control The The IF THEN ELSE structure is frequently used in programs The syntax IF THEN Structure is as follows IF lt boolean gt THEN lt statement gt ELSE lt statement gt ENDIF This executes certain statements only if specified conditions exist The following example demonstrates the IX THEN ELSE structure PROCEDURE MESSAGE PRINT Type your name INPUT name PRINT Would you like the message of the day name y n INPUT answers IF answer y THEN PRINT Space is the future ELSE PRINT Suit yourself ENDIF PRINT Bye name It s been nice talking to you END
68. N translate wordS Passes word by value When parameters are passed by value a temporary variable is created when the expression is evaluated The result is placed in temporary storage The address of this temporary storage is sent to the called procedure Therefore the value actually given to the called procedure is a copy of the result and the called procedure cannot change the variable s in the calling program Arrays Complex Data Types TYPE P Chapter 9 Data Types and Data Structures Important Expressions containing numeric constants are either INTEGER or REAL there is no type BYTE constant Thus BYTE type variables may be sent to a procedure as parameters but expressions will be of types INTEGER or REAL For example a RUN statement may evaluate an INTEGER as a parameter and send it to the called procedure If the called procedure is expecting a BYTE type variable it uses only the high order byte of the four byte INTEGER which if the value was intended to be in BYTE range is probably zero The DIM statement can create arrays of from one to three dimensions A vector is a one dimensional array A table is a two dimensional array A matrix is a three dimensional array The sizes of each dimension are defined when the array is typed for example DIM plot 24 80 BYTE by including the number of elements in each dimension Therefore a table dimensioned 24 80 has 24 rows 1 24 of 80 co
69. ND 2 23 Chapter 2 Getting Started Line Numbers and the GOTO Statement Now when you run this procedure your table will have a header You should experiment with the edit commands until you feel comfortable with them This makes creating and editing your procedures much easier As mentioned before the listing Basic displays is not in the exact format as the input There is a space between the I code address and the actual procedure This is reserved for line numbers Although line numbers are required in many versions of BASIC Microware BASIC does not require them Line numbers must be positive whole numbers in the range of 1 to 32767 They do not need to be used for every line They are generally used with a GOTO or GOSUB statement The GOTO statement transfers control unconditionally to the specified line For example PROCEDURE gotodemo PRINT This is a GOTO example GOTO 10 PRINT This line will never be printed 10 PRINT It works but it s dangerous END As you can see a GOTO statement could cause certain parts of a procedure s code to be excluded from execution There are generally better ways of obtaining the same results without ever using a GOTO statement The use of the GOSUB statement is discussed in detail in Chapter 3 Important If at all possible do not use line numbers or the GOTO statement Your procedures will be shorter faster and easier to ed
70. OR i 0 TO 10 tempt y IF i 0 THEN yi ytx ELSE y 1 ENDIF x temp PRINT i y NEXT i PROCEDURE fractions by T F Ritter ral finds increasingly close rational approximations E to the desired real value IM m INTEGER C wo uou LH desired PI last 0 FOR m 1 TO 30000 n INT 5 m desired trial n m IF ABS trial desired ABS last desired THEN PRINT n m trial PRINT difference trial desired PRINT last trial ENDIF NEXT m A 2 Appendix A Sample Programs PROCEDURE prinbi REM by T F Ritter REM prints t PARAM n INT DIM i INT EG EGER ER FOR i 31 TO 0 STEP IF n 0 THEN PRINT 1 ELSE PRINT 0 ENDIF nTn i RINT ja J PROCEDURE hanoi by T F Ritter amp amp See BYTE Magazine amp PARA EGER HEN RINT move 4 n from RUN hanoi n 1 from other to PRINT move 4 R n from UN hanoi n 1 other to from ENDIF Eri iw from to_ other he integer parameter value in binary move n discs in Tower of Hanoi game Oct 1980 pg 279 STRING 8 from C Da e TOS lIfTOomi CODD Ee A 3 Appendix A Sample Programs PROCEDURE roman R prints integer parameter as Roman Numeral PARAM x INTEGER
71. PRINT If information not available hit return INPUT name Phonebook name INPUT phone number Phonebook phone INPUT street address Phonebook address street INPUT city state Phonebook address cityst INPUT zip code Phonebook address zip PUT file Phonebook PRINT If finished type done INPUT Otherwise hit the return done UNTIL doneS done RETURN 300 REPEAT INPUT What number record would you like record SEEK file SIZE Phonebook record 1 GET file Phonebook PRINT name Phonebook name PRINT phone number Phonebook phone PRINT street address Phonebook address street PRINT city state Phonebook address cityst PRINT zip code Phonebook address zip PRINT If finished type done INPUT Otherwise hit the return done UNTIL doneS done RETURN 3 11 Chapter 3 Program Construction Complex Data Types and Subroutines Calling Procedures Procedures can often be used by other procedures BASIC allows procedures to call each other and a procedure can call itself The RUN statement calls an external procedure BASIC looks first in the workspace then the data directory and finally the execution directory If it is found outside the workspace BASIC loads and runs it The RUN statement syntax is as follows RUN lt proc name gt lt param gt lt param gt The RUN statement can include parameters a list of values to pass to
72. RR FALSE PEEK addr POS TRUE neg ok ok B 3 Appendix B Quick Reference Notes B 4 Appendix Basic Error Codes 10 Unrecognized Symbol 11 Excessive Verbage too many keywords or symbols 12 Illegal Statement Construction 13 I code Overflow need more workspace memory 14 Illegal Channel Reference bad path number given 15 Illegal Mode Read Write Update Dir only 16 Illegal Number 17 Illegal Prefix 18 Illegal Operand 19 Illegal Operator 20 Illegal Record Field Name 21 Illegal Dimension 22 Illegal Literal 23 Illegal Relational 24 Illegal Type Suffix 25 Too Large Dimension 26 Too Large Line Number 27 Missing Assignment Statement 28 Missing Path Number 29 Missing Comma 30 Missing Dimension 3 Missing DO Statement 32 Memory Full need more workspace memory 33 Missing GOTO 34 Missing Left Parenthesis 35 Missing Line Reference 36 Missing Operand 37 Missing Right Parenthesis 38 Missing THEN statement 39 Missing TO 40 Missing Variable Reference 4 No Ending Quote 42 Too Many Subscripts 43 Unknown Procedure 44 Multiply Defined Procedure 45 Divide by Zero 46 Operand Type Mismatch 47 String Stack Overflow 48 Unimplemented Routine 49 Undefined Variable Appendix C Basic Error Codes C 2 50 Floating Overflow 51 Line wit
73. THEN Function TRIMS response ENDIF continued on next page A 16 Appendix A Sample Programs makeproc continued INPUT Redirect Input IF response y OR re response Sponse Y THEN ReInput EI SE MReInput ti NDIF INPUT Redirect Outpu IF response y OR re ReOutput gt X ELSE DIF iral Z PRINT Options Op INPUT response IF response THEN Options TRIMS respo ENDIF DestDir TRIMS DestDir WRITE ProcPath t t response sponse Y THEN ReOutput tlonss 3 nse INPUT Destination Directory DestDir WRITE ProcPath TMode 1 pause READ DirPath DirLine INPUT Use all files m CopyAll response y WHILE NOT EOF 4DirPat READ DirPath DirLi i LEN TRIMS DirLine IF i 0 THEN j 1 WHILE j lt i AND MID DirLine j 1 lt gt DO j j 1 ENDWHILE FileName MIDS D continued on next page respons OR response Y h DO ne irLine k Jj k Appendix A Sample Programs makeproc continued IF NOT CopyAll THEN PRINT Use FileName INPUT response CopyFile response y OR response Y ENDIF IF CopyAll OR CopyFile THEN ProcLine Function 4 ReInput tSrcDir FileNam IF DestDir THEN
74. The computer s performance and even sometimes whether or not a computer can handle a particular problem depends on how the software stores data in memory and operates on it BASIC offers many possibilities for organizing and manipulating data There are many types of data You can have numerical data textual data etc but you can seldom mix data types Not only do they have different storage size requirements but they are logically incompatible For example it would be meaningless to multiply letters and punctuation Even within the same general kind of data there are different ways to represent data You can represent numbers in three different ways Each way has its own advantages and disadvantages You should use the way that fits your needs for each procedure To help you select the most appropriate way to store data variables BASIC provides five different basic data types BASIC also lets you create new customized data types based on combinations of the five basic types A data structure refers to storage for more than one data item under a single name Data structures can be composed of various data types Data structures are often the most practical and convenient way to organize large amounts of similar data The simplest kind of data structure is the array which is a table of values The table has a single name and the storage space for each individual value is numbered Arrays are created by DIM statements For example
75. a specific memory address The first expression is used as the absolute address to store the type BYTE result of the second expression POKE can alter any memory address so you must be careful when using it ATTENTION Using POKE with an invalid address causes BASIC to abort Chapter 11 Program Statements and Structure Examples POKE ADDR buffer 5 ASC A POKE 1200 14 POKE 1C00 FF POKE pointer PEEK pointer 1 same as alphabet ABCDEFGHIJKLMNOPQRSTUVWXYZ FOR i 0 to 25 POKE ADDR alphabet i 40 i NEXT i POKE ADDR alphabet 26 00 Control Statements Control statements affect the sequential execution of program statements They are used to construct loops or make decisions that alter program flow BASIC provides a selection of loop statements that allow you to create any kind of loop using sound structured programming style The control statements are IF THEN ELSE FOR NEXT WHILE DO REPEAT UNTIL LOOP ENDLOOP GOTO GOSUB RETURN ON GOTO RETURN ON GOSUB RETURN and ON ERROR GOTO IF THEN ELSE Control Statement Syntax IF lt bool expr gt THEN lt statements gt ELSE statements ENDIF IF lt bool expr gt THEN lt line gt Function The IF structure evaluates an expression to a BOOLEAN value If the result is TRUE the statement s immediately following the THEN are executed If an ELSE clause exists sta
76. able names as they appear in the input list The variables can be of any basic type and the input data must be of the same or compatible type The line is terminated by a carriage return There must be at least as many input items given as variables in the input list The length of the input line cannot exceed 256 characters Chapter 12 Files and Unified Input Output PRINT 12 4 If any error occurs type mismatch insufficient amount of data etc you must re enter the entire input line The following message is displayed followed by a new prompt INPUT ERROR RETYPE INPUT uses OS 9 s line input function READLN which performs line editing such as backspace delete end of file etc To perform input without editing use the GET statement To test if data is available from the keyboard without hanging the program use the INKEY function INKEy returns the number of characters in the data buffer Examples INPUT number nameS location INPUT 14 What is your selection choice INPUT What s your name name To read a single character without editing from the terminal DIM char STRING 1 GET 0 char Output to Path Syntax PRINT lt output list gt PRINT lt path num gt lt output list gt PRINT USING lt str expr gt lt output list gt PRINT lt path num gt USING lt str expr gt lt output list gt Function PRINT outputs the values of the items in
77. am Once you are in debug mode you can debug your program Usually after an error stops the program you should use the PRINT command to look at the present values of crucial program variables Bad values are usually quite apparent Perhaps you forgot to initialize a variable or forgot to increment a loop counter If examining variables is not fruitful you should place a PAUSE statement at the beginning of the suspected procedure or at a place within the code where you think things begin to go wrong Then rerun the program When the program hits the PAUSE statement it enters the debug mode Next turn the trace mode on and watch your program run Type D TRON Then press the carriage return key once for every statement you want to trace You will see the original source statement and if expressions are evaluated by the statement debug mode prints an equal sign and the result of the expression Notice that some statements such as FOR and PRINT may cause more than one expression to be evaluated Using this technique you can watch your program run one step at a time until you see where it goes wrong If in the process of tracing you encounter a loop that works but executes 200 statements repetitively you do not have to trace line by line In this case you may turn the trace off and use the STEP command to quickly run through the loop Then turn trace mode back on and resume single step debugging The command sequence for this i
78. am when you change from a WHILE DO loop to a REPEAT UNTIL loop by forgetting to change the conditional statement Chapter 2 Getting Started The LOOP ENDLOOP Loop The final type of loop structure available in BASIC is the LOOP ENDLOOP statement It has no built in control statement to test for exit so it uses an internal structure the EXITIF THEN statement The syntax for these two structures are as follows LOOP lt statements gt EXITIF lt boolean gt THEN lt statements gt ENDEXIT lt statements gt ENDLOOP The LOOP structure would execute endlessly without the EXITIF construct You can use the EXITIF structure as many times as needed within a LOOP In this way you may exit a loop for different reasons The following is an example of a LOOP ENDLOOP x 1 LOOP PRINT x is a small number x X 1 EXITIF x 3 THEN PRINT x is now greater than three ENDEXIT ENDLOOP The execution of this procedure is similar to the REPEAT UNTIL The loop is executed until x gt 3 Then the statement between the THEN and the ENDEXIT is executed PRINT The loop is then exited You can omit the statement to be executed in the EXITIF loop For example you could enter EXITIF x 3 THEN ENDEXIT This is known as a null statement because nothing occurs Chapter 2 Getting Started Editing Your Procedures 2 18 The EXITIF THEN
79. ame is a string variable of 40 characters maximum address and city are string variables of 32 characters each and zip is a real variable Array Declarations Arrays can have one two or three dimensions The DIM statement format is the same as for simple variables except each name is followed by a subscript s to indicate its size The maximum subscript size is 2 147 483 647 although memory may limit this You can mix simple variable and array declarations in the same DIM statement DIM a 10 b 20 30 c INTEGER x 5 5 5 STRING 12 In this example a is an array of 10 integers b is a 20 by 30 table of integers c is a simple integer variable and x is a matrix of 12 character strings Arrays can be any basic or user defined type By declaring arrays of user defined types structures of arbitrary complexity and shape can be generated PARAM Chapter 11 Program Statements and Structure The following is an example declaration that generates a doubly linked list of character strings Each element of the array consists of the string containing the data and two integer pointers YPE link_pointers fwd back INTEGER YPE element info STRING 64 ptr link_pointers DIM list 100 element index INTEGER make a circular list BASEO FOR index 0 TO 99 list index info secret message STRS index list index ptr fwd index l list index ptr back
80. ammers When a file is created it has a length of zero It expands automatically as you send data to it Closing Files When you open a path to a file you must close it Notice the line at the end CLOSE file The CLOSE statement closes the specified path number Never close a path that you did not open unless absolutely required A New Phonebook Example The following procedure creates a random access file to hold Phonebook records It assigns the prompted values to the individual Phonebook data fields one at a time It places the entire data structure into the file at one time Chapter 3 Program Construction Complex Data Types and Subroutines PROCEDURE Phonebook YPE rec street STRING 30 cityst STRING 30 zip STRING 9 YPE ENTRY name STRING 30 phone STRING 20 address rec DIM Phonebook ENTRY DIM file INTEGER CREATE file phonebook UPDATE PRINT Enter the information asked for by the prompt PRINT If information not available hit return REPEAT INPUT name Phonebook name INPUT phone number Phonebook phone INPUT street address Phonebook address street INPUT city state Phonebook address cityst INPUT zip code Phonebook address zip PUT file Phonebook PRINT If finished type done INPUT Otherwise hit the return doneS UNTIL done done CLOSE file
81. and produce Operators have precedence which means they are evaluated in a specific order for example multiplication is performed before addition You can use parentheses to override natural precedence The compiler however may remove extraneous parentheses The legal operators are listed below in order from highest to lowest Table 2 D Legal Operators Highest Precedence NOT negate AN l lt c AND Lowest precedence OR XOR Operators of equal precedence are shown on the same line and are evaluated left to right in expressions The only exception to this rule is exponentiation which is evaluated right to left Raising a negative number to a power is not legal in BASIC Chapter 2 Getting Started In the examples below BASIC expressions on the left are evaluated as indicated on the right You may enter either form but the compiler always generates the simpler form on the left BASIC representation Equivalent form a b c 2 d a b c 2 d a b gt c AND d gt e OR c e a b gt c AND d gt e OR c e a b c d e a b c d e a b c d e a b c d e a b 2 a z b 2 a b c a b c returns BOOLEAN value Operator Function Operand type Result type Negation UMERIC UMERIC ROAF Exponentiation UMERIC positive UMERIC Multiplication UMERIC U
82. and tends to hide the structure of the program The number of characters on a line is dependent on the content of the line In general lines should be limited to 128 characters or less to avoid the generation of errors when BASIC decompiles the I code for listing purposes or at run time Loop nesting is limited to 39 levels Nested procedure and subroutine calls are only limited by stack space Program readability is improved if all variables are declared with DIM statements at the beginning of the procedure but this is not mandatory Chapter 11 Program Statements and Structure Assignment Statements LET 11 2 Line numbers are optional They can be any integer number in the range of 1 to 32767 Only use line numbers where absolutely necessary such as with GOSUB They make programs harder to understand use additional memory space and increase compile time considerably Line numbers are local to procedures That is the same line number can be used in different procedures without conflict You can terminate programs with END or STOP statements These statements are optional Assignment statements are used for computing or initializing of variables The two assignment statements available with BASIC are LET and POKE Assignment State Syntax LET lt var gt lt expr gt LET lt var gt lt expr gt LET lt struct gt lt struct gt LET lt struct gt lt struct gt Functi
83. are Name Function Page Fibonacci Computes first eleven Fibonacci numbers A 2 Fractions Finds rational approximations for real values A 2 Prinbi Prints integer value in binary A 3 Hanoi Moves n discs in Tower of Hanoi game A 3 Roman Prints integer value as a Roman numeral A 4 Eightqueens Finds the arrangement that eight queens may be A 5 placed on a chess board without conflict Electric Prints pictorial representation of the electrical field A 6 around charged points Structst Example of intermixed array and record structures A 8 Wordlook Displays word at given address by use of A 9 Subroutines Prinbyte prints byte as binary Qsortl Example quicksort with use of subroutine A 10 Exchange exchanges values of two variables Sortest Procedure to test Qsortl with use of subroutine A 11 Prin prints an array of 1000 integers Upadd Upsub Demonstrates multiple precision arithmetic using A 12 Uprint Upinput five integers to represent a forty decimal digit Uptoreal Ultra number with eight fractional places Patch Examines and patches any byte of a disk file using A 14 the subroutine PrintAS CIl MakeP roc Generates an OS 9 command file to apply A 16 a command SysCall Subroutine to use OS 9 system calls A 19 Appendix A Sample Programs PROCEDURE fibonacci R computes the first eleven Fibonacci numbers DIM x y i temp INTEGER E x 0 y 0 F
84. ate the manufacturing process while providing access to vital plant floor data that can be used to support decision making throughout the enterprise ASIA PACIFIC CANADA LATIN AMERICA HEADQUARTERS HEADQUARTERS HEADQUARTERS Allen Bradley Hong Kong Allen Bradley Canada Allen Bradley Limited Limited 1201 South Second Street Room 1006 Block B Sea 135 Dundas Street Milwaukee WI 53204 USA View Estate Cambridge Ontario NIR Tel 414 382 2000 28 Watson Road 5X1 Telex 43 11 016 Hong Kong Canada FAX 414 382 2400 Tel 852 887 4788 Tel 519 623 1810 Telex 780 64347 FAX 519 623 8930 FAX 852 510 9436 PN 955113 16 Printed in USA
85. ax CHAIN lt SHELL command line gt Function CHAIN performs an OS 9 chain operation on the shell passing the specified command line as a parameter CHAIN causes BASIC to be exited unlinked and its memory returned to OS 9 The command line should evaluate to the name of an executable module such as BASIC passing parameters if appropriate CHAIN can begin execution of any module not just BASIC It executes the module indirectly through the shell This allows CHAIN to use the shell s parameter processing This leaves an extra active shell Programs that repeatedly chain to each other eventually find all memory filled with waiting shells To prevent this use the shell s ex option Consult Using Personal OS 9 or Using Professional OS 9 for more details on the capabilities of the shell Important If it is necessary to pass an open path to another program using the CHAIN command use the shell s ex option Examples CHAIN ex BASIC menu CHAIN BASIC 10k sort datafile tempfile CHAIN DIR DO CHAIN Dir Echo Copying Directory ex basic09 copydir 11 19 Chapter 11 Program Statements and Structure SHELL 11 20 Create a Shell Process Syntax SHELL lt SHELL command line gt Function SHELL allows BASIC programs to run any OS 9 command or program SHELL gives access to virtually any OS 9 function including multiprogramming utility commands
86. cified number of lines before the current line are delete The forms d or d are also allowed They delete all lines before or after the current line respectively d deletes the entire procedure I lt number gt Lists the specified number of lines from the current edit pointer If the number is negative the specified number of lines before the current line is displayed I lists the entire procedure q Quits the editor and returns to system mode r lt number gt Renumbers the numbered lines in a procedure The r command lt increment gt begins at the current line and renumbers the first numbered line found with the specified number After that it increments the line number by the specified increment If an asterisk is used the renumbering begins with the start of the procedure This also renumbers any references to line numbers GOTO or IF THEN statements The default values for renumbering are a starting value of 100 with an increment of 10 s lt del gt lt string gt lt del gt Searches for the indicated string on the current line If an asterisk is used the entire procedure is searched and the pointer is moved to the first matching string Delimiters del follow the same rules as the c command escape Quits the editor Chapter 2 Getting Started Using the Edit Mode Commands To use the editor you must be in edit mode You can use these commands to crea
87. cii STRING nextchar BYTE i INTEGER ascii wi FOR i 1 TO 16 nextchar line char i IF nextchar gt 127 THEN nextchar nextchar 128 ENDIF IF nextchar lt 32 OR nextchar gt 125 THEN ascii asciit ELSE ascii ascii CHRS nextchar ENDIF NEXT i PRIND N 35041 Appendix A Sample Programs PROCEDURE MakeProc Generates an OS 9 command file to apply a command Such as copy del etc to all files in a directory or directory system Author L Crane DIM DirPath ProcPath i j k INTEGER DIM CopyAll CopyFile BOOLEAN DIM ProcName FileName ReInput ReOutput response STRING DIM SrcDir DestDir DirLine STRING 80 DIM Function Options STRING 60 DIM ProcLine STRING 160 ProcName CopyDir Function Copy Opt ions b 32k REPEAT PRINT Proc name ProcName PUT response IF response THEN ProcName TRIMS response DIF s ON ERROR GOTO 100 ELL del ProcName n I LH 100 ERROR PUT Source Directory SrcDir rcDir TRIMS SrcDir ERROR GOTO 200 HELL del procmaker dir n ON H O 200 ON ERROR SHELL dir u SrcDir gt procmaker dir OPEN DirPath procmaker dir READ CREATE ProcPath ProcName WRITE PRINT Function Function 3 INPUT response IF response
88. d Structure Generate Error Syntax ERROR lt integer expr gt Function ERROR generates an error having the error code specified by the result of evaluation of the expression ERROR is often used for testing error routines Also see the ON ERROR description Suspend Execution Syntax PAUSE lt output list gt Function PAUSE suspends execution of the procedure and causes BASIC to enter debug mode If an output list is specified it also executes as a PRINT statement When a PAUSE is encountered the following is displayed lt output list gt BREAK IN PROCEDURE lt procedure name gt You can use the debug mode CONT command to resume procedure execution at the following statement Examples PAUSI PAUSI now outside main loop 11 23 Chapter 11 Program Statements and Structure CHD CHX DEG RAD 11 24 Change Directories Syntax CHD lt pathlist gt CHX lt pathlist gt Function CHD and cxx change the current default data or execution directories respectively The pathlist must refer to a file which has the DIR attribute For more information on the OS 9 directory structure consult Using Personal OS 9 or Using Professional OS 9 Set Angle Units to Degrees or Radians Syntax DEG RAD Function DEG and nap set the procedure s state flag to assume angles stated in degrees or radians in SIN COS TAN ACS ASN and ATN functions This flag applie
89. discarded Values outside the INTEGER range are converted to REAL values Consequently they return an input error when passed to a procedure as integers Additionally certain functions LAND LNOT LOR LXOR use integer values but produce results on a non numeric bit by bit basis The REAL data type is the default type for undeclared variables However a variable may be explicitly typed REAL for example twopi REAL to improve a program s internal documentation REAL type values are always printed with a decimal point and only those constants which include a decimal point are actually stored as REAL values REAL numbers are stored in eight consecutive memory bytes The representation is based on the double precision format of IEEE Draft Standard 754 Bit 7 of the first byte is the sign of the mantissa Bits 0 6 of the first byte and bits 4 7 of the second byte form the exponent The exponent is biased by 1024 The remaining 52 bits comprise the mantissa The mantissa has an implied leading one bit 9 3 Chapter 9 Data Types and Data Structures Internal Representation of REAL Numbers BYTE 0 1 2 3 4 6 s lt exponent gt lt mantissa gt t Mantissa Sign The exponent covers the range 2 2 10 308 24 1022 through 1 8 10 308 2 1024 as powers of 2 Operations which result in values out of the representation range cause overflow or underflow errors which may be handled au
90. dure EDIT Enters edit mode to create or change a procedure Important You cannot directly enter debug mode from system mode Description Chapter 5 System Mode Shell Command Syntax lt text gt Function This command calls the OS 9 shell command interpreter to process an OS9 command or to run another program Running the shell command does not disturb BASIC or its workspace If the dollar sign is followed by text the shell is called to process the text as a single OS 9 command line After the command is executed BASIC is immediately re entered If no text is specified BASIC is suspended and the OS 9 shell is called to process multiple command lines individually entered from the keyboard BASIC regains control when an end of file character usually escape is entered The contents of the BASIC workspace are not affected This is a convenient way to temporarily leave BASIC to manipulate files or perform other housekeeping tasks This command is the gateway from BASIC to OS 9 It allows access to any OS 9 command or to other programs It also permits creation of concurrent processes and other real time functions Examples Command Description B copy file1 file2 Calls the OS 9 copy command B 168 sourcefile amp Calls the assembler as a background task B basic fourier 20 amp Starts another concurrent BASIC program 5 3 Chapter 5 System Mode BYE or lt eof gt character
91. dure Syntax LIST lt procname gt lt procname gt gt lt pathlist gt LIST lt pathlist gt Function LIST prints a formatted listing of one or more procedures LIST prints a formatted listing of all procedures in the workspace The listing includes the relative I code storage addresses in hexadecimal format in the first column The second column is reserved for program line numbers if line numbers are used If a pathlist is given the listing is output to that file or device This option is commonly used to print hard copy listings of programs LIST prints on the OS 9 standard error path 2 if no pathlist is given Important If an asterisk is used the file name lt pathlist gt follows immediately without a greater than sign gt before it Examples LIST p LIST prog2 prog3 gt p LIST prog5 gt temp 5 7 Chapter 5 System Mode LOAD MEM 5 8 Load Procedure into Workspace Syntax LOAD lt pathlist gt Function LOAD loads all procedures from the specified file into the workspace As procedures are loaded their names are displayed If any of the procedures being loaded have the same name as a procedure already in the workspace the existing procedures are erased and replaced with the procedure being loaded If the workspace fills up before the last procedure in the file is loaded an error 32 is given In this case not all procedures may have been loaded and the
92. e of subroutines ON GOSUB The syntax for this statement is as follows ON lt int expr gt GOSUB lt line gt lt line gt subroutine E TURN lt line gt subroutine ETURN lt line gt Don WON ON GOSUB evaluates the lt int expr gt and transfers control to the corresponding line number in the list following GOSUB If the integer is greater than the number of line numbers in the list no subroutine is executed When used with a previous input statement ON GOSUB can run menu type subroutines Chapter 3 Program Construction Complex Data Types and Subroutines The following is the Phonebook procedure written with subroutines PROCEDURE Phonebook YPE rec street STRING 30 cityst STRING 30 zip STRING 9 YPE TRY name STRING 30 phone STRING 20 address rec DIM Phonebook ENTRY flag BOOLEAN file answer record INTEGER flag TRUE ON ERROR GOTO 100 CREATE file phonebook UPDATE flag FALSE T 100 IF flag THEN OPEN file phonebook UPDATE ENDIF ON ERROR REPEAT PRINT TYPE 1 for add new entries PRINT 2 for access previous entries PRINT 3 for exit procedure INPUT answer ON answer GOSUB 200 300 UNTIL answer 3 CLOSE file END 200 SEEK file FILSIZ file REPEAT
93. eain ft EE E Ne ex E ete IE BASEBO BASB T eerie epe RR RR ERU ER X AES ee TRON TROEF 1i 5 uos ROI eR OO G RD ha VES SG GU Comment Statements 0 0 cece een REMIC ux uid aeui tacts ute ieee te 3 Am Tace i web he EA Table of Contents 05 9 BASIC User Manual Files and Unified Chapter 12 Input Output Files and Unified Input Output 0000 0 I anccul mq CLOSE i1 225b5ReeneBlbATaoe db dl eae need hoa curd dried a GBT BUT iue heed eR bI rd ee RI AT ERE EG Ra DATA READ RESTORE sssecasea hh e hend Formatted Output The Print Using Statement Real Bormat iuo br EPAEL pee UU as Rude diese ud us Y Exponential Format 0 0 0 eee eee ened Integer Format 55254 eR BiG RRS RA RS oS PRES HES RAR PS Hexadecimal Format ic cent ida keok dae chad iba e teed ed String Format gt ees 66 2 she Se Se ee ee ee Ed eed Boolean Format 112v tert ed deed eeu leas ea age aes Control Specifications 0 0 eee eee eee ees Repeat Groups s e doriy diaa e A E e een ened Sample Programs Appendix A Quick Reference Appendix B Basic Error Codes Appendix C JJ c UJ Appendix D The BASIC Tutorial This section of the manual describes a how new Microware BASIC users can become comfortable with programming BASIC how users get started programming BASIC complex data types and subroutines that you can use with Microware BASIC
94. edure in a file with the specified name name Type SAVE and a file This saves all procedures in your workspace in the specified file name Type SAVE followed by This saves the specified procedures in the specified file one or more procedures followed by a followed by a file name Important If you exit from BASIC your programs will not automatically be saved You must save them using one of these methods or they will be lost Naming Your Procedure Getting Started Programs in BASIC are called procedures A procedure contains BASIC instructions as specified by the BASIC language Procedures are created in edit mode To enter edit mode type e and the name of the procedure you want to create B e myprogram Procedure names may contain from 1 to 28 upper or lower case letters numbers or special characters as listed below While the file name may begin with any of the following characters or digits the file name must contain at least one number or letter Within these limits a name may contain any combination of the following Description Character upper case letters A Z underscores i lower case letters a Z dollar signs numbers 0 9 periods If you do not specify a procedure name BASIC assigns the name Program to the new procedure BASIC responds with the following B e myprogram PROCEDURE myprogram mi BASIC prints the word PROCEDURE and
95. either case paramcheck examines str1 By isolating the parameter checking the program keeps its integrity and allows for easy maintenance A question mark option is added to print a help message The help message explains how to use the procedure PROCEDURE Phonebook PARAM pstrl string YPE rec street STRING 30 cityst STRING 30 zip STRING 9 YPE ENTRY name STRING 30 phone STRING 20 address rec DIM Phonebook ENTRY flag BOOLEAN file answer INTEGER DIM strl string record 0 flag TRUE strl oops ON ERROR GOTO 5 strl pstrl 5 RUN paramcheck strl answer record ON ERROR ON ERROR GOTO 100 CREATE file phonebook UPDATE flag FALSE IF flag THEN OPEN file phonebook UPDATE ENDIF ON ERROR REPEAT IF answer lt 1 THEN PRINT TYPE for add new entries PRINT 2 for access previous entries PRINT 3 for exit procedure INPUT answer ENDIF ON answer GOSUB 200 300 UNTIL answer 3 CLOSE file END SEEK file FILSIZ file REPEAT PRINT If information not available hit lt return gt INPUT name Phonebook name INPUT phone number Phonebook phone INPUT street address Phonebook address street INPUT city state Phonebook address cityst INPUT zip code Phonebook address zip PUT fi
96. ement have been evaluated the next DATA statement is used If there are no more DATA statements following processing wraps around to the first data statement in the program The RESTORE statement used without a line number causes the first DATA statement in the program to be used next If it is used with a line number the data statement having that line number is used next Example DATA 1 2 3 4 DATA 5 6 7 8 100 DATA 9 10 11 12 FOR N 1 TO X READ ARRAY N NEXT N RESTORE 100 d EAD A B C D Formatted Output The Print Using Statement Chapter 12 Files and Unified Input O utput BASICOO has a powerful output editing capability useful for generating reports and other applications where formatted output is required The output editing uses the PRINT USING statement PRINT lt path gt USING str expr gt output list You can use the optional path number expression to specify the path number of any output file or device If it is omitted the output is written to the standard output path The string expression is evaluated and used as a format specification This contains specific formatting directives for each item in the output list Blanks are not allowed in format strings The items in the output list can be constants variables or expressions of any type As each output item is processed it is matched up with a specification in the format list The type of each expression
97. erstanding of the problem The result is likely to be hard to understand and hard to update if program specifications change The identification of efficient algorithms and their clear structured expression is indicative of professionalism in software design BASIC Reference Guide This section of the manual describes BASIC s four command modes Mode Description SYSTEM Used for executing system commands EDIT Used for creating editing procedures EXECUTION Used for running procedures DEBUG Used for testing procedures for errors Certain commands in each mode will change BASIC s mode The following is a graphic representation of which commands accomplish this and what mode they are carried out in BASIC Mode Changes 0S 9 SYSTEM MODE EDIT MODE CHD t C eof CHX z d L BYE EDIT 43 5 lt r DIR KILL space r LIST LOAD q S MEM PACK escape BASIC RENAME SAVE a gt DIGITS RUN DEBUG MODE TRON FQ TROFF EXECUTION MODE zl DEGRAD bin END PAUSE gt BREAK CONT lt crtl E gt ERROR gt LET STATE RUNB STOP ctl C gt PRINT BASIC r BYE LIST AUTORUN STEP Chapter 16 Batch Processing Overview Syntax Notation Used in System Command Descriptions Individual descriptions of the available commands in each mode follow In order to precisely describe their formats
98. f Debug Mode Debug Mode Symbolic debugging is the testing and manipulation of programs using the actual names and program statements used in the program This is accomplished by BASIC s powerful symbolic debugging commands BREAK CONT DEG RAD DIR LET LIST PRINT Q STATE This chapter discusses how the debug mode can let you watch your program run in slow motion This allows you to observe each statement as it is executed This chapter also includes how to use the debug mode as a calculator Debug mode is entered from execution mode in one of three ways when an error occurs during execution of a procedure that is not intercepted by an ON ERROR GOTO statement within the program when a procedure executes a PAUSE statement when a keyboard interrupt ctr1 c occurs When any of the above happen debug mode displays the suspended procedure name like this BREAK PROCEDURE test5 D Important Debug mode displays a D prompt when it is waiting for a command You can then use any debug mode command to examine or change variables turn trace mode on off etc Depending on which commands are used execution of the program can be terminated resumed or executed one source line at a time 8 1 Chapter 8 Debug Mode Shell Command Syntax text Function calls OS 9 s shell command interpreter to run a program or OS 9 command This command execute
99. fast I code interpretation often results in many MPU instruction cycles such as execution of floating point arithmetic operations Also BASIC Icode instructions that reference variable storage statements labels etc contain the actual memory addresses so no table searching is ever required In addition BASIC fully exploits the power of the 68000 s instruction set which was optimized for efficient execution of compiler produced code BASIC I code is interpreted Therefore a variety of entry time tests run time tests and development aids are available to help in program development aids not available on most compilers The editor reports errors immediately when they are entered The debugger allows debugging using the original program source statements and names The I code interpreter performs run time error checking of things such as array bound errors subroutine nesting arithmetic errors and other errors that are not detected and usually crash native compiler generated code 4 1 Chapter 4 Program Optimization Optimum Use of Numeric Data Types Looping Quickly 4 2 BASIC includes several different numeric representations REAL INTEGER and BYTE and performs automatic type conversions between them You can easily write expressions or loops that take at least ten times longer to execute than is necessary Some BASIC numeric operators and control structures FOR NEXT include versions
100. file N 1 address 3 New York NY customer file X balance 125 98 The complex structure allows you to create appropriate data types by providing more natural organization and association of data Additionally the position of the desired element is known and defined at compilation time and need not be calculated at run time unlike arrays Therefore they can be accessed faster than arrays Type Structure Size Occasionally you need to know the exact size of a data structure Each basic data type is stored in a certain format Type Memory format BYTE One Byte INTEGER Four Bytes REAL Eight Bytes STRING One Byte Character BOOLEAN One Byte While it would seem easy to just add the components sizes together to find the size of the entire structure it is not that simple BASIC only starts INTEGERS REALS and complex data structures on an even word boundary Additionally complex data structures are of even word length Therefore BASIC pads certain structures with an empty byte For example the size of the following structure s individual components add up to nine bytes TYPE junk a BYTE b c INTEGER The actual size of this structure is ten bytes BASIC inserts a byte between a and b 11 31 Chapter 11 Program Statements and Structure 11 32 The following examples show different data structures and their corresponding size Structure TYPE demo a BYTE b REAL
101. g information the name of the item a 25 byte character string the item s list price and cost both real numbers and the quantity on hand an integer First use TYPE to define a new data type that describes such a record TYPE inv item name STRING 25 list cost REAL qty INTEGER 12 13 Chapter 12 Files and Unified Input Output 12 14 This statement describes a new record type called inv_item but does not assign variable storage for it Next create two data structures an array of 100 records of type inv_item called inv_array and a single working record called work_rec DIM inv array 100 inv item DIM work rec inv item To calculate the total size of each record you can manually count the number of bytes assigned for each type or use the built in SIZE function SIZE returns the number of bytes assigned to any variable array or complex data structure The syntax is as follows SIZE lt name gt For this example SIZE work_rec returns the number 46 and SIZE inv_array returns 4600 srz amp is often used with SEEK to position a file pointer to a specific record s address The following procedure creates a file called inventory and initializes it with zeroes and nulls PROCEDURE makefile TYPE inv item name STRING 25 list cost REAL qty INTEGER DIM inv array 100 inv item DIM work rec inv item DIM path byte CREATE path inventory
102. ge the value of the conditional within the loop If you do not the loop never exits For example the following is an endless loop because the internal commands do not affect the conditional statement a 5 WHILE a lt 10 DO PRINT This is an endless loop ENDWHILE Chapter 2 Getting Started The REPEAT UNTIL Loop Another loop statement is REPEAT UNTIL It is similar to the WHILE DO statement The syntax is as follows REPEAT UNTIL lt boolean gt The major difference is that in a REPEAT UNTIL statement the conditional statement is tested at the bottom of the loop This means that the statements within the loop are executed at least once even if the conditional statement is false the first time The following is an example of a loop using REPEAT UNTIL xe REPEAT PRINT x x x 1 UNTIL x gt 10 Notice again that x is initialized outside of the loop If it were initialized inside of the loop the loop would never end The next statement REPEAT begins the loop The statements within the loop are always executed during the first pass The UNTIL statement tests the conditional value If the statement is false the loop executes again If the statement is true the loop is not executed again Because the variable is tested at the bottom of the loop it usually has an opposite test from one you would find in a WHILE loop You can easily introduce errors into your progr
103. gns the numeric value of each character in the string to the corresponding element of the byte array Define Data Types Syntax TYPE lt typename gt lt type decl gt Function TYPE defines new data types New data types are defined as a vector a one dimensional array of previously defined types This structure differs from an array in that the various elements may be of different types and the elements are accessed by field name instead of an array index The syntax of the type decl gt conforms to the syntax of the DIM and PARAM statements For example TYPE cust_recd name address 3 STRING balance This example creates a new data type called cust_recd which has three named fields afield called name which is a string afield called address which is a vector of three strings a field called balance which is a default REAL value TYPE can include previously defined types so that you can create complex structures such as lists and trees TYPE does not create any variable storage itself the storage is created when the newly defined type is used in a DIM statement The following example creates an array having 250 elements of type cust recd cust recd is defined above DIM customer file 250 cust recd Chapter 11 Program Statements and Structure To access elements of the array in assignment statements the field name and the index are used nameS customer file 35 name customer_
104. gt lt str gt with trailing spaces removed The following functions return BOOLEAN values Name Description TRUE Always returns TRUE FALSE Always returns FALSE EOF num End of file test on disk file path num returns TRUE if end of file condition exists 10 6 Program Structure Program Statements and Structure A BASIC program can be written as a single procedure or it may be divided into a number of smaller procedures each of which performs a specific function Single procedure programs may be useful when the program is relatively small However large complex programs are generally much easier to develop test and maintain when the program is divided into several procedures To do this you should create a main routine which calls other BASIC procedures to perform specific functions as subroutines These BASIC procedures may in turn call other BASIC procedures in the same manner These techniques reflect sound structured programming practice A procedure consists of any number of program statement lines Each line can have an optional line number More than one program statement can be placed on the same line if separated by backslash characters For example the following statements are equivalent GOSUB 550 PRINT X Y RETURN GOSUB 550 PRINT X Y RETURN While these statements are functionally equivalent the second is generally considered preferable The first method runs no faster
105. h Compiler Error 52 Value out of Range for Destination 53 Subroutine Stack Overflow 54 Subroutine Stack Underflow 55 Subscript out of Range 56 Parameter Error 57 System Stack Overflow 58 I O Type Mismatch 59 I O Numeric Input Format Bad 60 I O Conversion Number out of Range 61 Illegal Input Format 62 I O Format Repeat Error 63 I O Format Syntax Error 64 Illegal Path Number 65 Wrong Number of Subscripts 66 Non Record Type Operand 67 Illegal Argument 68 Illegal Control Structure 69 Unmatched Control Structure 70 Illegal FOR Variable 71 Illegal Expression Type 72 Illegal Declarative Statement 73 Array Size Overflow 74 Undefined Line Number 75 Multiply Defined Line Number 76 Multiply Defined Variable 77 Ilegal Input Variable 78 Seek Out of Range 79 Missing Data Statement 80 Print Buffer Overflow Error codes above 80 are those used by OS 9 or other external programs Consult Using Personal OS 9 or Using Professional OS 9 for a list of error codes and explanations Appendix C Basic Error Codes Notes C 3 Appendix RUNB Runb is the BASIC run time package It is similar to BASIC with the following exceptions Runb is about half the size of BASIC and no file editing or debugging can be done The main purpose of Runb is to save space and to execute packed modules It should be noted tha
106. han sign gt before it Examples SAVE proc2 proc3 proc4 gt monday work SAVE newprogram SAVE SAVE gt testprogram Edit Mode Edit Mode Commands You use the edit mode the editor to create or modify BASIC procedures To enter edit mode from system mode use the EDIT or E command When you enter edit mode the prompt E is displayed If you have used a text editor before you will find the BASIC editor similar to many others except for these two differences The editor is both string and line number oriented Using line numbers is optional and you can correct text without re typing the entire line The editor is interfaced to the BASIC compiler and decompiler This lets BASIC perform continuous syntax error checking and allows programs to be stored in memory in a more compact compiled form The editor includes the following commands Each command is described in detail later in this chapter Command Description r Movethe edit pointer forward one line lt number gt Moves the edit pointer forward lt number gt Moves the edit pointer backward lt space gt lt text gt Inserts an unnumbered line lt space gt lt line gt lt text gt Inserts or replaces a numbered line lt line gt lt cr gt Finds a numbered line C Changes a string d Deletes a line Lists line s q Quits editing r Renumbers line S Searches for string esc Quits editing
107. has concerning the error One such piece of information is the I code address Basic automatically supplies I code addresses Now run the procedure To run a procedure you must be in system mode You can exit the editor and return to system mode by typing q Ua EADY w m n Now type run myprogramor run If you enter the RUN command without a procedure name BASIC executes the last edited procedure B RUN myprogram type your name Ellen Hi Ellen It s been nice talking to you READY Bs Important The question mark prompt tells you that the program is waiting for input Congratulations You have just written and executed your first program with Microware BASIC Procedures use variables to hold values during the execution of the procedure The value of a variable may change during execution In the example myprogram name was used as a variable to hold the value Ellen There are two ways of declaring a variable the DIM statement inferred declaration The DIM statement declares the variable name and the type of data that is assigned to it during the course of the procedure The DIM statement must occur before you use the variable in the program This prevents a variable from being defined with a default data type inferred declaration By standard convention the DIM statement is used in the first few lines of a procedure Chapter 2 Getting Started The syntax for the DIM statement is a
108. he result to select a corresponding line number from an ordered list Control is then unconditionally transferred to that line number in ON GOTO statements or as a subroutine in ON GOSUB statements These statements are similar to CASE statements in other languages Each lt line gt in the ordered list is given a value beginning with 1 2 3 integer expr gt must evaluate to a positive INTEGER result having a value between 1 and N N being the highest line number in the list N is limited by input line length and the number of digits in each line number The best case limit for N is 60 Important If the expression has a result that does not correspond with the ordered list no GOSUB statement is selected and the next sequential statement is executed Chapter 11 Program Statements and Structure Example spell out the digits 0 to 7 DIM digit INTEGER A one digit only please INPUT type in a digit digit ON digit l GOSUB 10 11 12 13 14 15 16 17 PRINT AS STOP names of digits 0 AS ZERO RETUR 11 AS ONE RETUR 12 AS TWO RETUR 13 A THREE RETUR 4 AS FOUR RETUR 15 AS FIVE RETUR 16 AS SIX RETUR 17 AS SEVEN RETUR ON ERROR GOTO Control Statement Syntax ON ERROR GOTO line gt Function This statement sets a tra
109. iew BYE Exiting BASIC When you have finished using BASIC and have saved all procedures that you want to save you can exit BASIC by typing the command BYE at the system prompt B BYE You are returned to your OS 9 shell prompt DIR Listing Procedure Names in Your Workspace The DIR command displays the names and sizes of all procedures in your workspace You can also use a carriage return while in system mode DIR displays a table of all procedure names with two numbers next to each name The first column proc size is the size of the corresponding procedure The data size column shows the amount of memory that the procedure requires for its variables For example B DIR Name Proc Siz Data Siz testprog 226 66 prog2 162 82 exloop 220 74 readit 224 66 4266 free Ready Bs The last line shows the amount of free bytes of workspace memory remaining You may use this information to estimate how much memory your program needs to run You must have at least as much free memory as the data size of the procedure s to be run If a data size number is followed by a question mark you need more memory EDIT Entering Edit Mode When you enter the EDIT or E command you exit system mode and enter edit mode To enter edit mode type EDIT or E and the name of a procedure file to edit e myprocedure Chapter 1 Overview If you do not enter a procedure file BASIC assigns the name Program to your procedure The EDIT c
110. is that Important If a string parameter is in expression format as above or could be construed as a numeric parameter 12 or 1 5 the parameter must be within double quotes If you run a program from BASIC you must use parentheses as if the procedure was being called from another procedure For example run filter zzmyfiles p 1 11 Optional Parameters A parameter passing error only occurs if a parameter is accessed that has not been passed to a procedure No error occurs however if too few or too many parameters are passed as long as the missing parameters are not accessed The variables expecting parameters are not initialized if no matching parameters are passed Consequently you should create some sort of parameter handling subroutine for procedures receiving fewer parameters than expected By adding a command line parameter to the Phonebook procedure you can create a help message for a first time user and an immediate access to records The key to this type of strategy is finding whether a parameter has been passed and if so which one A second variable str1 is declared to trap the parameter It is initialized to the string oops If the parameter is not passed the ON ERROR routine passes control to the paramcheck routine If a parameter is passed str1 is set to pstr1 and the paramcheck routine is run 100 200 Chapter 3 Program Construction Complex Data Types and Subroutines In
111. it There is less chance of error If you must use a GOTO statement use it sparingly and always document the code with a comment Putting It All Together PROC EDURE s DI DI DI PRI INP PRI PRI PRI INP Chapter 2 Getting Started With the various control statements and editing commands presented in this chapter you should be able to write some fairly advanced procedures For example the following program was written using just what you have learned in this chapter multable less BOOLEAN answer STRING 1 a b c INTEGER NT Type your name UT names NT Hi name Ye NT Would you like to print a multiplication table NT Type y for yes Type any other key for no UT answer IF answer y THEN PRINT What is the number you want to multiply PRINT please specify a number between 1 and 100 INPUT a PRINT What is the range of the multiplication table PRINT type 2 numbers between 1 and 50 separated by a space INPUT b c WHILE b c DO PRINT Please specify two different numbers for the range INPUT b c ENDWHILE D c REPEAT PRINT Thank you name ount 1 PRINT b r5 as S b a F POS gt 55 THEN PRINT Bd H IF b c THEN b b 1 less FALSE b b 1 ENDIF UNTIL b c 1 AND less OR b c 1 AND NOT less ELS E PRINT Your loss
112. le Phonebook PRINT If finished type done INPUT Otherwise hit the return done UNTIL done done answer 0 RETUR 3 15 Chapter 3 Program Construction Complex Data Types and Subroutines 300 REPEAT IF record 0 THEN H PUT What number record would you like record DIF SEEK file SIZE Phonebook record 1 GET file Phonebook hel PRINT name Phonebook name PRINT phone number Phonebook phone PRINT street address Phonebook address street PRINT city state Phonebook address cityst PRINT zip code Phonebook address zip PRINT If finished type done INPUT Otherwise hit the return done record 0 UNTIL doneS done answer 0 RETURN PROCEDURE Paramcheck PARAM strl1 STRING answer record INTEGER IF strl THEN PRINT Syntax phonebook lt opt gt PRINT Function This is a little black book for phone numbers PRINT lt opt gt prints this message PRINT a add mode allows you to add phone numbers PRINT r rec specifies the phone number desired PRINT rec the record number of the phone address STOP ELSE IF stri a THEN answer 1 ELSE IF LEFT strl 3 2 rz THEN record VAL MID str1 4 LEN str1 3 answer 2 ELSE answer 0 ENDIF ENDIF
113. lied to only that procedure This example displays the procedure named justin LIST justin The asterisk is a special name that indicates all procedures in the workspace Therefore if you enter the following command all procedures in the workspace are displayed LIST If you do not enter a name with the command the current working procedure is used The current working procedure is the procedure specified for the last command The DIR command prints an asterisk before the current working procedure s name This allows you to check which procedure is current 5 1 Chapter 5 System Mode 5 2 If you have not yet given a name in any command BASIC automatically uses the name Program Some commands require a file name and one or more procedure names They usually require that a greater than sign gt precede the file name so that it is not mistaken for a procedure name If you omit the file name the name of the first procedure is used Important In this manual the phrase file name means an OS 9 pathlist which describes either a file or device Here are some examples SAVE tom bill gt myfile SAVE big_file SAVE tic tac toe same as SAVE tic tac toe gt tic The RUN and EDIT commands use only one procedure name or the current working name if a name is omitted These commands change BASIC s mode by exiting the command mode and entering another mode Command RUN Enters execution mode to run a proce
114. lt statements gt ENDEXIT Function LOOP ENDLOOP and EXITIF ENDEXIT are inherently related They can be used to construct loops with tests located anywhere in the body of the loop The LOOP and ENDLOOP statements define the body of the loop EXITIF clauses can be inserted anywhere inside the loop to leave the loop if the result of its test is true Important If there is no exit clause you will create an endless loop EXITIF ENDEXIT allows control to be passed to the next statement outside the structure containing the EXITIF statement this includes IF THEN statements EXITIF evaluates an expression to a boolean result If the result is TRUE the statements between the THEN and the ENDEXIT are executed and control is transferred outside the binding structure Otherwise the statement following ENDEXIT is executed This exit clause is often used to perform some specific function upon termination of the loop which depends on where the loop terminated EXITIF statements are almost always used when LOOP ENDLOOP is used but they can also be useful in any type of loop or conditional construct Chapter 11 Program Statements and Structure GOTO 11 10 Examples LOOP is equivalent to count count 1 EXITIF count gt 100 THEN done TRUE ENDEXI PRINT count ENDLOOP INPUT x y LOOP PRINT EXITIF x 0 THEN PRINT x became zero firs
115. lumns 1 80 when accessed in the default BASE 1 mode You may elect to access the elements of an array starting at zero BASE 0 in which case there are still 24 rows now 0 23 and 80 columns now 0 79 Arrays may be composed of basic data types complex data types or other arrays The TYPE statement defines a new data type as a vector a one dimensional array of any basic or previously defined types For example mployee rec name STRING number 2 INTEGER malesex BOOLEAN This structure differs from an array in that the various elements may be of mixed types and the elements are accessed by a field name instead of an array index For example DIM employee file 250 employee rec employee file 1 name Tex employee file 20 number 2 115 9 9 Chapter 9 Data Types and Data Structures The complex structure allows you to store and manipulate related values that are of many types to create new types in addition to the five defined data types or to create data structures of unusual shape or size The position of the desired element in complex type storage is known and defined at compile time and need not be calculated at run time Therefore complex structure accesses may be slightly faster than array accesses The elements of a complex structure may be copied to another similar structure using a single assignment operator An entire structure may be written to or read from mass storage
116. most often used to call a procedure inside the workspace but it can also be used to call a previously compiled procedure or a 68000 machine language procedure outside the workspace The name can be optionally taken from a string variable Parameter Passing RUN can include a list of parameters enclosed in parentheses to be passed to the called procedure The called procedure must have PARAM statements of the same size and order to match the parameters passed to it by the calling procedure The parameters can be variables constants or the names of entire arrays or data structures They can be of any type except variables of type BYTE However BYTE arrays are allowed If a parameter is a constant or expression it is passed by value A parameter passed by value is evaluated and placed in a temporary storage location and the address of the temporary storage is passed to the called procedure Parameters passed by value can be changed by the receiving procedure but the changes are not reflected in the calling procedure If the parameter is the name of a variable array or data structure it is passed by reference When passed by reference the address of that storage is sent to the called procedure and the value in that storage may be changed by the receiving procedure These changes are reflected in the calling procedure 11 15 Chapter 11 Program Statements and Structure 11 16 Calling External Procedures If the procedure
117. most statements can be used with any I O device or file Sometimes certain statements are used in unusual ways by advanced programmers to achieve certain special effects Statement Generally used with Data format file type INPUT Keyboard interactive input Text Sequential PRINT Terminals Printers Text Sequential OPEN Disk Files and I O Devices Any CREATE Disk Files and I O Devices Any CLOSE Disk Files and I O Devices Any DELETE Disk Files Any SEEK Disk Files Binary Random READ Disk Files Text Sequential WRITE Disk Files Text Sequential GET Disk Files and I O Devices Binary Random PUT Disk Files and 1 0 Devices Binary Random Accept Input Syntax INPUT lt path num prompt input list Function INPUT accepts input during the execution of a program Input is normally read from the standard input device terminal unless an optional path number is specified When the INPUT statement is encountered execution is suspended and a question mark prompt prompt is displayed INPUT is both an input and output statement If the optional prompt string is specified it is displayed instead of the normal prompt Therefore if a path other than the default standard input path is used open the path in update mode This makes INPUT dangerous if used on disk files Unless you like prompts in your data use READ The entered data is assigned in order to the vari
118. n happen if the original program had extraneous spaces between keywords unnecessary parentheses in expressions etc BASIC keywords are always automatically capitalized When you finish editing the procedure use the q for quit command to exit edit mode and return to system mode When you enter the q command the compiler passes over the entire procedure again At this time syntax that extends over multiple lines is checked and errors reported Examples of these errors are 1 GOTO or GOSUB to a non existent line missing variable or array declarations improperly constructed loops These errors are reported using an error code and the hexadecimal I code address of the error For example OlFC ERR 000 043 Line Number Oriented Editing Chapter 6 Edit Mode This message means that error number 43 was detected in the line that included I code address 01FC hexadecimal The LIST command gives the I code addresses so you can locate lines with errors reported during the compiler s second pass The editor can work on programs with or without line numbers If you use line numbers they must be positive whole numbers in the range of 1 to 32767 If you have used another version of the BASIC language this is the kind of editing you probably used However well structured programs seldom really need line numbers Do not use line numbers unless they are necessary By not using line number your programs will be shorter faster
119. n to the file device specified in OS 9 memory module format suitable for loading in ROM or RAM outside the workspace BASIC automatically loads the packed procedure when you try to run it later Here is an example sequence that demonstrates packing a procedure PACK sort Packs procedure sort and creates a file KILL sort Kills procedure inside the workspace RUN sort Run sort is loaded outside of the workspace KILL sort Done delete sort from outside memory The last step does not have to be done immediately if you will be using the procedure again later but you should kill it when you are done so its memory can be used for other purposes Important The packed file cannot be loaded into the workspace later on Always perform a regular SAVE before packing a procedure Example PACK procl proc2 gt packed programs 5 9 Chapter 5 System Mode RENAME RUN Rename a Procedure Syntax RENAME lt procname gt lt new procname gt Function RENAME Changes the name of a procedure It can be used to allow two copies of the same procedure in the workspace under different names Example RENAME thisproc thatproc Execute a Procedure Syntax RUN lt procname gt lt expr gt lt expr gt J Function RUN executes the specified procedure BASIC leaves system mode and enters execution mode You can use a parameter list to pass expected parameters to the procedure
120. nal it is not required at the bottom of a procedure Examples END END I have finished execution Stop Procedure Execution Syntax STOP lt output list gt Function STOP immediately terminates execution of all procedures and returns to the command mode If an output list is specified it also executes like a PRINT statement 11 21 Chapter 11 Program Statements and Structure BYE DIGITS 11 22 End Procedure Execution and BASIC Syntax BYE Function BYE ends execution of the procedure and terminates BASIC Any open files are closed and any unsaved procedures or data in the workspace is lost You can use BYE to create packed programs and or programs to be called from OS 9 procedure files ATTENTION Bye causes BASIC to abort Only use it if the program has been saved before it is tested Set Precision Syntax DIGITS lt int expr gt Function DIGITS controls the precision of real numbers displayed by a PRINT statement If no lt int expr gt is specified DIGITS returns the current precision DIGITS also controls the precision of transcendental functions If the result of the expression is not between 1 and 15 the result is brought into that range with no error Example PROCEDURE DIGITDEMO DIM a b REAL DIGITS 2 a 9 2 b 0 11 PRINT a b a b RUN DIGITDEMO 9 52 Ld T ERROR PAUSE Chapter 11 Program Statements an
121. named by RUN cannot be found in the workspace BASIC checks to see if it was loaded by OS 9 outside the workspace If it is not found there BASIC tries to find a disk file having the same name in the current execution directory loads it and runs it In either case BASIC checks to see if the called procedure is a BASIC I code module or a 68000 machine language module and executes it accordingly If it is a 68000 machine language module BASIC executes a JSR instruction to its entry point and the module is executed as 68000 native code The machine language routine can return to the original calling procedure by executing an RTS instruction The diagram on the next page shows what the stack frame passed to machine language subroutines looks like Machine language modules return error status by setting the carry bit of the MPU condition codes register and by setting the low order word of register D1 to the appropriate error code For an example of a machine language subroutine SYSCALL see Appendix A After an external procedure has been called but is no longer needed the KILL statement should be used to get rid of it so its memory space can be used for other purposes Example PROCEDURE trig_table numl 0 num2 0 REPEAT RUN display numl SIN numl RUN display num2 COS num2 PRINT UNTIL numl gt 1 END PROCEDURE display PARAM passed funcval PRINT passed funcval
122. ng a negative number to a power is not legal in BASIC In the following examples BASIC expressions on the left are evaluated as indicated on the right Either form may be entered but the decompiler always generates the form on the left BASIC representation Equivalent form a b c 2 d a b4 c 2 d a b gt c AND d gt e OR c e a b gt c AND d gt e OR c e a b c d e a b4c 4d e a b c d e a b c d e a b 2 a b 2 a b c a b c returns BOOLEAN value Chapter 10 Expressions Operators and Functions Functions 10 4 Functions accept one or more arguments enclosed in parentheses perform some operation and return a value They may be used as operands in expressions Functions expect that the arguments passed to them are expressions constants or variables of a certain type and return a result of a certain type Giving a function an argument of an incompatible type results in an error In the descriptions of functions that follow the following notation describes the type required for the parameter expressions Name Description lt num gt Specifies any numeric result expression lt str gt Specifies any string result expression lt int gt Specifies any integer result expression The functions below return REAL results Accuracy of transcendental functions is 8 decimal digits Angles can be either degrees or radians see DEG RAD statement descriptions
123. number and it may be either an integer or a real If it is a real data type for example STEP 5 the control variable must also be a real data type The following is an example of a real data type for the STEP value DIM x REAL FOR x 1 TO 5 STEP 5 PRINT x EXT x END This example prints the value of x for each pass through the loop Chapter 2 Getting Started The WHILE DO Loop The WHILE DO loop tests for a control variable before executing any code It continues to loop as long as the control statement located in the WHILE statement remains true If the control statement in the WHILE statement is false the first time it is encountered the loop is not executed The WHILE DO loop has the following syntax WHILE lt boolean gt DO ENDWHILE boolean may be an expression such as x 5 or merely a BOOLEAN variable such as WHILE red DO The following is an example of a WHILE DO loop x 1 WHILE x 5 DO PRINT x x x 1 ENDWHILE The first line is outside of the WHILE DO loop but it is important for this loop because it initializes the value of x The next line begins the loop It tells BASIC to test the value of x If x is less than five then the statements inside the loop are executed If the value of x is five or greater the statements inside the loop are not executed Therefore the output from this loop looks like this BW NH Important You must chan
124. ny initial value if needed ATTENTION BASIC does not automatically initialize Procedures may pass variables to other procedures When this occurs the variables passed to the called procedure are referred to as parameters Parameters may be passed in two ways Name Description by reference This allows values to be returned from the called procedure to calling procedure variables by value This protects the values in the calling procedure so that the called procedure cannot change them Parameters are usually passed by reference This is done by enclosing the names of the variables to be sent to the called procedure in parentheses as part of the RUN statement The storage address of each parameter variable is evaluated and sent to the called procedure which then associates those addresses with names in a local PARAM statement The called procedure uses this storage as if it had been created locally although it may have a new name and can change the values stored there Parameters passed by reference allow called procedures to return values to their callers Parameters may be passed by value by writing the value to be passed as an expression which is evaluated at the time of the call Useful expression generators that do not alter values are 0 for numbers or for strings For example 6699 RUN inverse x Passes x by reference RUN inverse x 0 Passes x by value RUN translate word Passes word by reference RU
125. of Workspace Syntax DIR lt pathlist gt Function DIR displays the name size and variable storage requirement of each procedure presently in the workspace The current working procedure has an asterisk before its name All packed procedures have a dash before their name see PACK The available free memory within the workspace is also given If a pathlist is specified output is directed to that file or device 5 5 Chapter 5 System Mode EDIT E KILL KILL 5 6 A question mark next to a data storage size means the workspace does not have enough free memory to run that procedure Important Do not confuse this command with the OS 9 dir command They have completely different functions Enter Edit Mode Syntax EDIT lt procname gt E lt procname gt Function EDIT E exits system mode and enters edit mode If the specified procedure does not exist a new one is created See the next chapter for a complete description of how edit mode works Examples E newprog EDIT newprog Delete Procedure from Workspace Syntax KILL lt procname gt lt procname gt KILL Function KILL deletes the procedure s specified by lt procname gt KILL clears the entire workspace This process may take some time if there are many procedures in the workspace Examples KILL formulas KILL progl prog2 prog7 LIST LIST Chapter 5 System Mode Display Listing of Proce
126. ommand is discussed in more detail in the next chapter KILL Deleting Procedures in Your Workspace At any time you may permanently erase one or all of your procedures in your workspace by using the KILL command KILL followed by a procedure name erases the specified procedure KILL erases all procedures in the workspace For example Command Description B KILL progl Erases progl from workspace B KILL Erases all procedures from workspace LOAD Loading Procedures To retrieve a procedure from your current data directory you can use the LOAD command followed by the name of the file B LOAD oldprog This command loads the file oldprog into your workspace If you have a procedure in your workspace with the same name as one in the file BASIC uses the procedure loaded from the file MEM Displaying or Requesting Workspace Memory When you enter BASIC OS 9 automatically allocates approximately 4K of workspace memory for BASIC If you need more memory you can use the MEM command to get additional memory if the additional memory is available To use the MEM command type MEM and the amount of memory you want in bytes For example MEM 20000 This command line requests 20K of memory BASIC always rounds the amount you request up to the next highest multiple of 256 bytes If MEM displays the following the requested amount of memory is not available What Chapter 1 Overview You can also use OS 9 s lt memor
127. on LET evaluates an expression and stores the result in lt var gt lt var gt may be a simple variable or data structure element The result of the expression lt expr gt must be of the same or compatible type as lt var gt BASIC accepts either or as an assignment operator However the second form is preferred because it distinguishes the assignment operation from a comparison the test for equality The operator is also used in PASCAL You can also use the assignment statement to copy the entire value of an array or complex data structure to another array or complex data structure The data structures do not have to have the same type or shape The only restriction is that the size of the destination structure be the same or larger than the source structure You can use this type of assignment to perform unusual type conversions For example a string variable of 80 characters can be copied to a one dimensional array of 80 bytes Chapter 11 Program Statements and Structure Examples A 0 1 value temp sin x DIM array1 100 array2 100 arrayl array2 LET AUTHORS FIRST NAMES LAST NAMES DIM truth lie BOOLEAN lie 100 lt 1 truth NOT lie count total adjustment matrix 2 coefficient n 2 matrix 1 coefficient n POKE Store Data at Specific Memory Address Syntax POKE integer expr gt byte expr gt Function POKE allows a program to store data at
128. one being loaded when the workspace became full may not be completely loaded You should KILL the last procedure use the MEM command to get more memory or KILL unnecessary procedure s to free up space and then LOAD the file again Example LOAD quadratics Display or Request Workspace Memory Syntax MEM lt number gt Function MEM used without a number displays the present total workspace size in decimal bytes If a number is given BASIC asks OS 9 to expand or contract the workspace to that size A hex value can be used if preceded by a dollar sign If MEM responds with What you either asked for more memory than is available tried to give back too much memory there has to be enough to store all procedures in the workspace or gave an invalid number PACK PACK Chapter 5 System Mode Example MEM 18000 Pack Procedure Syntax PACK lt procname gt lt procname gt gt lt pathlist gt PACK lt pathlist gt Function PACK Causes an extra compiler pass on the specified procedure s This removes names line numbers non executable statements etc The result is a smaller faster procedure s that cannot be edited or debugged but can be executed by BASIC or by the BASIC run time only program called RunB If a pathlist is not specified the name of the first procedure in the list is used as the file name The packed file is stored in your execution directory The procedure is writte
129. oping structure It is usually during these passes when a procedure produces errors which can halt execution BASIC supports four ways of adding loops into your program Type of loop Description FOR NEXT Executes code an exact number of times WHILE DO Tests for a control variable before executing any code and performs only as long as the control statement remains true REPEAT UNTIL Executes the code at least once regardless of the initial conditions and repeats the code as long as a control statement remains valid LOOP ENDLOOP Tests one or more control variables anywhere within the loop and perhaps more than once Each loop structure is discussed in greater detail When you write your programs you should use the most appropriate loop for what you want to accomplish each loop structure has its own advantages As a general comment about loops the initialization placement is very important You can easily create an endless loop a loop that does not end by forgetting to initialize variables or by placing the initialization in the wrong place This is especially true when changing from one type of loop structure to another You should make sure that you know what happens at the beginning and end of each loop sequence This helps reduce the chance of creating an endless loop The FOR NEXT Loop The FOR NEXT loop executes a set of statements a specific number of times A FOR NEXT loop begins with the FOR sta
130. or executing system commands Edit Mode Used for creating and editing procedures Execution Mode Used for running procedures Debug Mode Used for testing procedures for errors You must remember that BASIC does have different modes You should be aware that some commands only operate in one mode Therefore if you execute a command that you feel should work and it does not check that you are in the proper mode These modes are all discussed in more detail in the appropriate sections A full description of each mode is located in the reference section of this manual When you create procedures in BASIC they are created in BASIC s workspace The workspace is the memory area where procedures are created or loaded edited and executed The procedures in this area are not automatically saved when you exit BASIC Therefore you must save any files in your workspace before you exit BASIC Fundamental Commands There are several commands that you should know before beginning to program in BASIC These commands are as follows Command Description BYE E xt BASIC DIR Lists procedures currently in your workspace EDIT Enters edit mode KILL Deletes a procedure from your workspace LOAD Loads files from the OS 9 file system to your workspace MEM Displays or requests workspace memory PACK Compresses a BASIC procedure into BASIC intermediate code SAVE Saves your procedures in the OS 9 file system Chapter 1 Overv
131. original source lines as they are executed Important Because compiled I code contains actual statement memory addresses the top or bottom statements of loop structures are usually executed just once For example in FOR NEXT loops the FOR statement is executed once so the statement that appears to be the top of the loop is actually the one following the FOR statement Turn On Off Trace Mode Syntax TRON TROFF Function These commands turn the suspended procedure s trace mode on and off In trace mode the compiled code of each equivalent statement line is reconstructed to source statements and displayed before the statement is executed If the statement causes the evaluation of one or more expressions an equal sign and the expression result s are displayed on the following line s Trace mode is local to a procedure If the suspended procedure calls another no tracing occurs until control returns to the calling procedure unless the called procedure has trace mode on Debugging Techniques Chapter 8 Debug Mode If your program does not do what you expect it is sure to show one of two symptoms premature termination due to an error incorrect results The first case automatically sends you into debug mode In the second case you have to force the program into debug mode either by pressing Ctrl C assuming you have time to do so or by using edit mode to put one or more PAUSE statements in the progr
132. ou can write a simple procedure myprogram This procedure asks you for your name and prints a message The first line of the procedure asks you to enter your name E PRINT type your name You must enter a space before the PRINT statement If you forget to do this BASIC will not save your command If entered correctly when you execute myprogram the characters between the quotes will be printed on the terminal screen Important If you make a mistake while entering this procedure line skip ahead to the section in this chapter on editing procedures Because the user will try to enter their name the next statement reads their input E INPUT name Chapter 2 Getting Started Once again you must enter a space before the INPUT statement to save the line When this procedure is executed this command causes Basic to wait for a line of text to be received from the keyboard BASIC accumulates text from the keyboard character by character until a Return ends the line This text is saved in the memory reserved for the variable name Important Variables are discussed in more detail in a later section To finish this program enter the final two lines E PRINT Hi name It s been nice talking to you E END The semicolon following the quote after Hi tells BASIC that something else is to be printed on this line BASIC inserts the text that the variable name represents The next semicolon informs BAS
133. ou to change or locate a portion of a statement without having to type the entire statement 6 5 Chapter 6 Edit Mode In the editor strings must be surrounded by delimiters Delimiters are two matching characters located at the beginning and the end of a string The editor uses delimiters to locate the beginning and the end of strings The characters used for delimiters are not considered part of the string Therefore the character you use for a delimiter must not appear within the string Do not confuse the strings used by the editor with BASIC s data type which is also called STRING Although they have the same name they are quite different You can use the s command to locate the next occurrence or all occurrences of a string The format for this command is as follows s lt delim gt lt match str gt lt delim gt CR s lt delim gt lt match str gt lt delim gt CR The first format searches for the lt match str gt starting with the current line If any line at or following the edit pointer includes a sequence of characters that match the search string the edit pointer is moved to that line and the line is displayed If the string cannot be located the following message is displayed and the edit pointer remains at its original position CAN T FIND lt match str gt The s variation searches for all occurrences of the string in the procedure starting at the present edit pointer and displays all
134. p that transfers control to the specified line number when a non fatal run time error occurs If no ON ERROR GOTO has been executed in a procedure before an error occurs the procedure stops and enters DEBUG mode You can turn off the error trap by executing ON ERROR without a GOTO This statement is often used with the ERR function which returns the specific error code and the ERROR statement which artificially generates errors 11 13 Chapter 11 Program Statements and Structure Important ERR automatically resets to zero any time it is called Example List a file DIM path errnum INTEGER name STRING 45 DIM line STRING 80 ON ERROR GOTO 10 INPUT File name name OP path name READ LOOP READ path line PRINT line ENDLOOP hel 10 errnum ERR IF errnum 211 THEN end of file PRINT Listing complete CLOSE path END ELSE other errors PRINT Error number errnum 11 14 Execution Statements RUN Chapter 11 Program Statements and Structure Execution statements run procedures stop execution of procedures create shells or affect the current execution of the procedure Run Procedure Syntax RUN proc name gt lt param gt lt param gt Function RUN calls a procedure by name When that procedure ends control passes to the statement after the RUN statement It is
135. passed passed 0 1 END Figure 11 1 Chapter 11 Program Statements and Structure Stack Frame Passed to Machine Language Procedures more parameters higher addresses size of 2nd param addr of 2nd param 8 bytes size of 1st param return address addr of 1st param parameter count lt 68000 Stack Register Pointer Register Value 68000 Register D1 68000 Register DO 11 17 Chapter 11 Program Statements and Structure KILL 11 18 Stop Execution of Procedure Syntax KILL lt proc name gt Function KILL unlinks an external procedure possibly returning system memory and removes it from BASIC s procedure directory If the procedure is inside the workspace nothing happens and no error is generated KILL can be used with auto loading PACKed procedures as an alternative to CHAIN when program overlay is desired The procedure name may be optionally called from a string variable ATTENTION It can be fatal to OS 9 to KILL an active procedure When KILL is used with RUN both statements must use the same string variable which contains the name of the procedure See the first example below Examples LET procname average RUN procname KILL procname INPUT Which test do you want to run test RUN test KILL test CHAIN Chapter 11 Program Statements and Structure Execute Shell Command Line Synt
136. pe Arrays of any of these data types can be created using one two or three dimensions BYTE variables hold integer values in the range 0 through 255 which are stored as a single byte BYTE values are always converted to INTEGER values and or REAL values for computation thus they have no speed advantage over other numeric types However BYTE variables require only a quarter of the storage used by integers and an eighth of that used by reals Attempting to store an integer value outside the BYTE range to a BYTE variable results in the storage of the least significant 8 bits the value modulo 256 without error The INTEGER Data Type The REAL Data Type Chapter 9 Data Types and Data Structures INTEGER variables consist of four bytes of storage These bytes hold a numeric value in the range 2 147 483 648 through 2 147 483 647 as signed 32 bit data Decimal points are not allowed INTEGER constants may also be represented as hexadecimal values in the range 00000000 through FFFFFFFF to facilitate address calculations INTEGER values are printed without a decimal point INTEGER arithmetic is faster and requires less storage than REAL values Arithmetic which results in values outside the INTEGER range does not cause run time errors but instead wraps around modulo 4 294 967 296 for example 2 147 483 647 1 yields 2 147 483 648 Division of an integer by another integer yields an integer result and any remainder is
137. perators precedence precedence of 2 10 command line processing 11 19 commands processing 5 3 output formatted formatting numerical 5 5 output editing directives P PACK PARAM parameter passing parameters command line optional passing passing by reference 9 8 passing by value 9 8 path closing defined opening path number PAUSE POKE precedence for operators 10 3 of operators 2 10 PRINT D 2 8 1 PRINT USING procedures calling 3 12 calling external 11 16 changing 5 10 compressing creating 1 2 16 1 current working 5 1 stop execution 11 21 stopping execution 11 18 structure 11 1 testing 16 1 testing for errors 1 2 program optimization 4 1 PUT 5 Q Q 2 4l s 1 8 5 quitting BASIC 5 4 R random access files 3 4 3 5 using 3 8 random access files 12 1 READ REAL defined formatting real format recursion 9 7 REM RENAME repeat groups 12 25 REPEAT UNTIL RETURN RUN defined string format strings changing defined locating 6 6 replacing searching 6 1 searching for 2 18 substituting 6 6 subroutine 3 10 system commands T table 3 1 9 9 the FOR NEXT structure 2 13 the IF THEN structure 2 12 the LOOP ENDLOOP structure 2 13 the REPEAT UNTIL structure 2 13 the TYPE declaration the WH
138. pes are mixed in expressions because the result of some operator or function has a different type than its operands An example is the less than operator 24 lt 100 The less than operator lt operator compares two numeric operands The result of the comparison is of type BOOLEAN in this case the value TRUE BASIC allows you to mix the three numeric types because it performs automatic type conversion of operands If different types are used in an expression the result is the same type as the operand s having the largest representation As a rule any numeric type operand may be used in a expression that is expected to produce a result of type REAL Expressions that must produce BYTE or INTEGER results must evaluate to a value that is small enough to fit the representation BASIC has a complete set of functions that can perform compatible type conversion Type mismatch errors are reported by the second compiler pass when leaving edit mode Chapter 10 Expressions Operators and Functions Operators Operators excepting negation perform some operation on two operands This produces a result which is generally the same type as the operands The following table lists the operators available and the types they accept and produce Operator Function Operand type Result type Negation NUMERIC NUMERIC or Exponentiation UMERIC positi
139. r strings TRUE and FALSE BOOLEAN values result from comparing two compatible types BOOLEAN values are appropriate for logical flags and expressions For example result a AND b AND c 9 5 Chapter 9 Data Types and Data Structures Automatic Type Conversion Constants Numeric Constants 9 6 Do not confuse BOOLEAN operations AND OR XOR and NOT with the logical functions LAND LOR LXOR and LNOT Logical functions use integer values to produce results on a bit by bit basis Attempting to store a non BOOLEAN value in a BOOLEAN variable or the reverse causes a binding error or an error on the second compiler pass when leaving edit mode Expressions that mix numeric data types BYTE INTEGER or REAL are automatically and temporarily converted to the largest type necessary to retain accuracy In addition certain BASIC functions also perform automatic type conversions as necessary Therefore numeric quantities of mixed types may be used in most cases Type mismatch errors happen when an expression includes types that cannot legally be mixed These errors are reported by the second compiler pass which automatically occurs when you leave edit mode Type conversions can take time Therefore you should use expressions containing all values of a single type wherever possible Constants are frequently used in program statements and in expressions to assign values to variables BASIC has rules that allow you
140. r saving memory space when 32 characters are not needed the default STRING size is 32 characters To declare a STRING length type dim followed by lt variable name gt STRING len For example to declare the variable word with a length of five characters you would type DIM word STRING 5 The BOOLEAN variable is most often used in conditional statements to divert execution to certain parts of the procedure If something is true then do this otherwise continue Important For more information about data types refer to the chapter on data types and data structures Constants Constants are frequently used in procedures to assign values to variables BASIC has rules that allow you to specify constants that correspond to the five BASIC data types There are three basic types of constants numeric boolean string 2 8 Chapter 2 Getting Started Numeric Constants Numeric constants can be either REAL or INTEGER data types If a number constant includes a decimal point or uses the E format exponential form BASIC stores the number in REAL format regardless of whether the number could have been stored in INTEGER or BYTE format If you want a REAL constant use a decimal point for example 12 0 This is sometimes done if all other values in an expression are of type REAL so that BASIC does not have to do a time consuming type conversion at run time Numbers that do not have a decimal point but are too large
141. r1 c keyboard interrupt Important In the first two cases you return to system mode In the last two cases you enter debug mode Chapter 7 Execution Mode Execution Mode Technically Speaking 7 2 The RUN statement is simple and normally you do not need to know what is happening inside BASIC when you use it The technical description of execution mode that follows is given for the benefit of advanced BASIC programmers Execution mode is BASIC s state when you run any procedure It involves executing the Icode of one or more procedures inside or outside the workspace Many procedures can be in use because they can call each other or themselves and nest exactly like subroutines You can enter execution mode in two ways the RUN system command BASIC s auto run feature The auto run feature allows BASIC to get the name of a file to load and run from the same command line used to call BASIC The file can be either a SAVED file in the data directory or a PACKED file in the execution directory The file may contain several procedures the one executed is the one with the same name as the file Parameters may be passed following the specified pathname When using the auto run feature upon finishing execution control returns to BASIC s command mode For example the following OS 9 command lines use this feature BASIC printreport Past Due Accounts BASIC evaluate COS 7 8814 12 075 22 5 129 055 Overview o
142. r_path The result is PRINT what is name s age PRINT index i TAB 25 value value print an 8 character line of all dashes REPEAT PRINT UNTIL POS gt 80 PRINT 12 5 Chapter 12 Files and Unified Input Output OPEN Open Path Syntax OPEN lt path num pathlist access mode gt Function OPEN issues a request to OS 9 to open an I O path to an existing file or device The specified path number can be a variable If so it must be dimensioned as type INTEGER or BYTE It receives the path number OS 9 assigned to the path The path number references the specific file device in subsequent input output statements The pathlist must be within quotes A string variable is allowed It is evaluated and passed to OS 9 as the descriptive pathlist oPEN may also specify the path s desired access mode which can be READ WRITE UPDATE EXEC or DIR The access mode defines which direction I O transfers occur If no access mode is specified UPDATE is assumed and both reading and writing are permitted The DIR mode allows OS 9 directory type files to be accessed but should not be used with WRITE or UPDATE modes The EXEC mode causes the current execution directory to be used instead of the current data directory For more information on files access modes refer to Using Personal OS 9 or Using Professional OS 9 Examples DIM printer path BYTE name STRIN
143. rectives Each has a corresponding one letter identifier Identifier Description R RealFormat E Exponential Format Integer Format H Hexadecimal Format S String Format B Boolean Format The letter is followed by a positive constant number called the field width This number indicates the exact number of columns in which to print the output It must allow for the data and overhead character positions such as sign characters decimal points exponents etc The field width must be between 1 and 255 3 17 Chapter 3 Program Construction Complex Data Types and Subroutines Some formats have additional mandatory or optional parameters that control subfields or select editing options Real and exponential formats use the fraction field to specify the number of digits to the right of the decimal point The fraction field is separated from the field width by a decimal point For example a field width of 10 and a fraction field of 6 is represented by 10 6 All formats can use the justification option This option specifies whether the output is to be centered left or right justified within the output field Fields are commonly right justified in reports because it arranges them into columns with decimal points aligned in the same position The symbols used in the justification specifications are lt left gt right center In the previous prin procedure the following print statement
144. rm I O functions than in other BASIC languages tis versatile By creating the appropriate data structures you can read or write almost any kind of data in any file including files created by other programs or languages These advantages are possible because a single GET or PUT statement can move any amount of data organized any way you want 12 15 Chapter 12 Files and Unified Input Output DATA READ RESTORE 12 16 Internal Data Statements Syntax DATA lt expr gt lt expr gt READ lt input list gt RESTORE line number Function These statements provide an efficient way to build constant tables within a program DATA statements provide values READ Statements assign the values to variables RESTORE statements set which data statement is read next The DATA statements have one or more expressions separated by commas They can be located anywhere in a program The expressions are evaluated each time the data statements are read and can evaluate to any type The following examples demonstrate DATA DATA 1 1 1 5 9999 CAT DOG DATA SIN temp 25 COS temp PI DATA TRUE FALSE TRUE TRUE FALSE The READ statement has a list of one or more variable names When executed it reads input by evaluating the current expression in the current data statement The result must match the variable type When all the expressions in a DATA stat
145. rpreter a high level interactive debugger and a system executive Each of these components is carefully integrated so you see a friendly highly interactive programming resource It provides all the tools and helpful facilities needed for fast accurate creation and testing of structured programs These features make Microware BASIC an ideal language for many applications scientific business industrial control and education Structured recursive BASIC with Pascal type enhancements allows multiple independent named procedures procedures called by name with parameters multi character upper or lower case identifiers variables and line numbers local to procedures line numbers optional automatic linkage to ROM or RAM library procedures PACK command compacts program and provides security PRINT USING with FORTRAN like format specifications Preface Introduction The History of Microware BASIC Extended Control Structures with Unique Closure Elements IF THEN ELSE ENDIF FOR TO STEP NEXT a REPEAT UNTIL WHILE DO ENDWHILE LOOP ENDLOOP EXITIF THEN ENDEXIT High speed high accuracy math 14 decimal digit 64 bit binary floating point Full set of transcendentals SIN ASN ACS LOG etc Extended data structures Five Basic data types BYTE INTEGER REAL BOOLEAN and STRING One two or three dimensional arrays User defined complex
146. s D TROFF D STEP 200 D TRON Chapter 8 Debug Mode Debug Mode as a Desk Calculator 8 8 Important Trace mode is local to one procedure only If the procedure being tested returns to another procedure you need to use the BREAK command or put a PAUSE statement in the procedure to enter debug mode If you call another procedure from the procedure being debugged tracing stops when it is called until it returns If you also want to trace the called procedure it needs its own PAUSE statement The simple program listed below turns debug mode into a powerful calculator Calculator declares 26 working variables then goes into debug mode This allows you to use interactive PRINT and LET statements PROCEDURE Calculator DIM a b c d e f g h i j k l m DIM ny Oy Dy GQ rS Cp uly Vp Wy Re VEZ PAUSE END Recall that while in debug mode you cannot create new variables Therefore DIM pre defines 26 working variables for you You can use more or fewer variables PAUSE causes you to enter debug mode The following is a sample session B run calculator BREAK PROCEDURE Calculator D let x 12 5 D print sin pi 2 Ds D let y exp 4 0 5 D print x y 125 90 0171313 D Q B Important The debug mode PRINT command can use PRINT USING to produce formatted output including hexadecimal Data Types Data Structures Data Types and Data Structures Computer programs process data
147. s BASEO BASEI 11 25 exit BASIC EXITIF ENDEXIT EXITIF THEN exiting BASIC 1 2 5 4 exponential format expression stack expressions evaluating external files 3 4 F field width file name defined 5 2 files closing creating loading FOR NEXT STEP format boolean 12 24 exponential 12 20 hexadecimal 12 22 formated output formatted output 3 17 fraction field 3 18 functions 10 G GET 3 5 GET PUT 12 13 GOSUB hexadecimal format 12 22 Du I code address listing 5 7 I code addresses 2 4 IF THEN ELSE INPUT 2 2 12 3 INTEGER defined integer format K KILL 12 4 5 1 5 9T 11 18 L 6 5 lines deleting 2 18 6 1 6 5 inserting 2 18 6 1 6 4 listing 6 6 1 sal load files LOOP ENDLOOP LOOP ENDLOOP 11 9 looping defined 2 13 endless 2 13 LOOP ENDLOOP D 17 nesting 2 13 REPEAT UNTIL 2 16 speed 4 2 the FOR NEXT structure 2 13 the LOOP ENDLOOP structure 2 13 the REPEAT UNTIL structure the WHILE DO structure 2 13 WHILE DO 2 15 loops 11 6 nesting 11 1 M matrix MEM memory display re 5 8 request 1 2 1 4 mode debug 1 2 16 1 edit 1 2 execution 1 2 16 1 system EN 16 1 I IV modes debug 8 1 execution N nested loops limitations 11 1 numeric data types 4 2 O ON ERROR GOTO 3 9 11 13 ON GOSUB ON GOTO OPEN o
148. s follows DIM lt variable gt lt variable gt lt data type gt If you declare more than one variable as the same data type separate the variables with commas If you declare more than one data type in the same DIM statement separate the lt var gt lt type gt statements with semicolons For example DIM x y z INTEGER a b c REAL In this example the variables x y and z are defined as integer values and a b and c are defined as real values If the DIM statement is not used and variables are present in a procedure the variables are declared with default data types All undeclared string variables must end in a dollar sign These variables are assigned a maximum length of 32 characters In the case of name in the example myprogram name was declared as a string variable with a length of 32 characters If the character string assigned to name is longer than 32 characters only the first 32 characters are accepted By default all other variables used are declared as REAL numbers regardless of the intent of the procedure Initializing Variables Generally you must initialize variables BASIC assigns a certain space in memory large enough to hold the declared type of data Consequently if the variables are not initialized the variable may contain just about any value This makes any operation depending on these variables to be very unreliable You can use either of two assignment statements to initialize variables
149. s only to the currently active procedure The default state is radians Example DIM a REAL DEG INPUT enter degree of angle a PRINT The sin of a degrees is SIN a END BASEO BASE1 TRON TROFF Chapter 11 Program Statements and Structure Set Low Array Index Syntax BASE 0 BASE 1 Function BASE 0 and BASE 1 indicate whether a particular procedure s lowest array or data structure index is zero or one The default is one These statements do not affect the string operations where the beginning character of a string is always index one Turn Trace Mode On Off Syntax TRON TROFF Function TRON and TROFF turn the trace mode on or off This is useful for debugging When trace mode is turned on each statement is decompiled and printed before execution The result of each expression evaluation is printed as it occurs 11 25 Chapter 11 Program Statements and Structure Comment Statements REM Comment Statement Syntax REM lt chars gt chars Function These statements are used to put comments in programs The second form of the statement is for compatibility with PASCAL programs Comments are retained in the I code but are removed by the PACK compile command The exclamation point character can be typed in place of the keyword REM when editing programs The compiler trims away extra spaces following REM to conserve memory space
150. s the same as the system mode command BREAK Set Breakpoint Syntax BREAK proc name Function BREAK sets a breakpoint at the specified procedure This command is used when procedures call each other and provides a way to re enter debug mode when returning to a specific procedure To illustrate how BREAK works suppose three procedures are in your workspace Procl Proc2 and Proc3 Assume that Procl calls Proc2 and Proc2 calls Proc3 While Proc3 is executing you type Ctr1 C to enter debug mode To use the BREAK command type D BREAK procl ok D Important BREAK responds with ok if the procedure was found on the current RUN stack You can use the STATE command to verify that the three procedures are nested as expected You can resume execution of Proc3 by typing cont After Proc3 terminates control passes back to Proc2 which eventually returns to Procl As soon as this happens the breakpoint you set is encountered Proc1 is suspended and debug mode is re entered 8 2 CONT DEG RAD Chapter 8 Debug Mode There are three characteristics of BREAK you should note The breakpoint is removed as soon as it occurs You can use one breakpoint for each active procedure You cannot put a breakpoint on a procedure unless it has been called but not yet re entered Therefore BREAK cannot be used on procedures that have not yet run Continue Execution Syntax CONT Function CONT contin
151. sists of a space followed by a BASIC statement line The statement is inserted just ahead of the edit pointer position The space itself is not inserted Chapter 6 Edit Mode Deleting Lines The d command deletes one or more lines d lt number gt CR d The first form deletes the specified number of lines starting at the edit pointer s current position If the number is negative that many lines before the current line are deleted If a line number is omitted only the current line is deleted The second form deletes all lines in the procedure The editor also accepts two variations of this command Command Description d4 Deletes all lines to the end of the procedure d Deletes all lines to the beginning of the procedure Important Be careful when using the d command You may delete lines unintentionally Listing Lines The command displays one or more lines 1 lt number gt CR 1 The first form displays the specified number of lines starting at the edit pointer s current position If the number is negative previous lines are listed The second form displays the entire procedure Neither form changes the edit pointer s position The line that is the current position of the edit pointer is displayed with a leading asterisk Search Finding STRINGS A string is a sequence of one or more characters This can include letters numbers or punctuation in any combination Strings allow y
152. st the current procedure PRINT STATE Chapter 8 Debug Mode Print Present Value of Variables Syntax PRINT lt expr gt USING lt expr gt lt expr list gt Function PRINT can be used to examine the present value of variables in the suspended program All variable names must be the same as in the original program You cannot use new variable names User defined data structures cannot be printed Quit Debug Mode Syntax Q Function Q terminates execution of all procedures and exits debug mode by returning to system mode Any open paths are closed at this point List Calling Order of Procedures Syntax STATE Function STATE lists the calling nesting order of all active procedures The highest level procedure is always shown at the bottom of the calling list and the lowest level procedure is always listed first Example D state PROCEDURE DELTA CALLED BY BETA CALLED BY ALPHA CALLED BY PROGRAM 8 5 Chapter 8 Debug Mode STEP TRON TROFF Single or Specified Line Execution Syntax STEP lt number gt or CR Function STEP executes the suspended procedure one or more source statements at a time For example step 5 executes the equivalent of the next five source statements A debug command line which is just a carriage return is considered the same as step 1 STEP is most commonly used with the trace mode on This allows you to see the
153. structure may be used in any of the looping structures to exit anywhere within the loop This allows greater freedom in building your procedures Once you have written a procedure you can change it by using the editor There are a number of commands available in edit mode for this purpose They are as follows Command Description lt return gt oves the edit pointer forward one line lt number gt ae the edit pointer forward the specified number of lines default is 0 oves the edit pointer to the end of the procedure lt number gt oves the edit pointer back the specified number of lines oves the edit pointer to the beginning of the procedure lt space gt lt text gt nserts a line directly before the current line space lt line gt lt text gt nserts or replaces a numbered line ines retum oves edit pointer to specified line c lt delim gt lt stringl gt lt delim gt lt string2 gt lt delim gt Replaces string1 with lt string2 gt in the current line If used with an asterisk the entire procedure is searched and replaced lt delim gt is a delimiter character that is not within either string For example c why why not c why why not Legal syntax Illegal syntax is in the string d line Deletes the specified lin elf no line is specified the current line is delete dif a negative number is specified the spe
154. t ENDEXI x x 1 ENDEXIT y y 1 ENDLOOP Control Statement Syntax GOTO lt line gt Function 100 EXITIF y lt 0 THEN PRINT y became zero first count count 1 IF count lt 100 THEN PRINT count GOTO 100 ELSE done TRUE ENDIF REM out of loop GOTO unconditionally transfers execution flow to the line having the specified number Important The line number is a constant not an expression or a variable Example GOTO 1000 Chapter 11 Program Statements and Structure GOSUB RETURN Control Statement Syntax GOSUB lt line gt lt line gt lt statements gt RETURN Function GOSUB transfers program execution to a subroutine starting at the specified line number The subroutine is executed until a RETURN statement is encountered which causes execution to resume at the statement following the calling GOSUB Subroutines may be nested to any depth Example FOR n 1 to 10 x SIN n GOSUB 100 NEXT n FOR m 1 TO 10 x COS m GOSUB 100 NEXT m STOP 100 x x 2 PRINT x RETURN 11 11 Chapter 11 Program Statements and Structure ON GOTO ON GOSUB 11 12 Control Statement Syntax ON lt integer expr gt GOTO lt line gt lt line gt ON lt integer expr gt GOSUB lt line gt lt line gt Function These statements evaluate an integer expression and use t
155. t Runb only executes packed modules Another feature of Runb is that ctr1 c and Ctr1 E can be trapped by ON ERROR GOTO where BASIC cannot When the name of a packed module is typed at the OS 9 prompt the shell determines that the module is packed BASIC I code The shell then loads and forks Runb and Runb links to and executes the named program To run packed modules in this way Runb must be in the commands directory Important Packed modules can be executed without Runb if they are still within the workspace but BASIC will have to be used and more space will be required Appendix D RUNB Notes Symbols 5 1 5 3 8 1 8 2 A access modes READ UPDATE WRITE 3 6 array 9 1 arrays po declaring assignment statement assignment statements 11 2 LET 11 2 POKE 11 3 B BASE 0 BASE conditional control constants 9 6 control specifications 12 25 control statements 11 4 FOR NEXT REPEAT UNTIL WHILE DO CREATE 3 6 3 7 12 7 creating procedures edit mode 2 1 16 1 fei current working procedure 5 11 5 5 D DATA data records DATA READ RESTORE 12 16 debug commands BREAK CONT 8 1 8 3 DEG RAD 8 1 8 3 STEP 8 6 TRON TROFF 8 6 debug moult 16 1 8 1 8 1 entering declaration statements 11 27 errors generating 11 23 EXEC 3 6 3 7 execution oe 1 2 21 16 1 7 a TRON TROFH 11 25 execution statemetn
156. t is negative the loop counts down Chapter 11 Program Statements and Structure The body of the loop the statements between the FOR and NEXT is executed until the NEXT variable a counter is larger than the terminating expression value For negative STEP values the loop executes until the loop counter is less than the termination value If the initial value of lt var gt is beyond the terminating value the body of the loop is never executed You can jump out of FOR NEXT loops ATTENTION When using REAL control and STEP A expressions there is a possibility of not completing the number of loops logically indicated For example the following loop would seem to complete x number of loops Due to the rounding nature of REAL numbers it may only complete x 1 loops FOR a 1 x TO 1 STEP 1 x next a To make sure that the loop is executed the correct number of times use INTEGER values for all expressions Examples FOR var min 1 TO mint max STEP increment adjustment PRINT var NEXT var FOR x 1000 TO 1 STEP 1 PRINT x NEXT x WHILE DO Chapter 11 Program Statements and Structure Control Statement Syntax WHILE lt bool expr gt DO lt statements gt ENDWHILE Function This loop tests its control expression at the top of the loop Statements within the loop are executed as long as lt bool expr gt is TRUE The body of the loop is not executed if the boolean e
157. te display and edit the procedure mtable This section goes step by step You should enter the commands on your own terminal First enter the command e mtable from the system mode B e mtable When you have pressed return the following is displayed PROCEDURE mtable Now enter the procedure Notice that you can type the procedure all in lower case characters When the procedure is displayed you will see that all reserved words have been converted to upper case letters Remember to add a space before each line E dim a b integer E print E while a 10 do E b 1 What The last two lines show what happens when you forget to add the lt space gt command before a line Just re type the line and continue E b 1 E while b lt 10 do E print a b a b tab mod b 5 13 E if pos gt 55 then print E ednif ednif Error 000 027 O00AE ERR ednif imi 2 19 Chapter 2 Getting Started The last six lines of this section show what happens if you make a mistake while typing in a command line If this happens enter an extra carriage return and re type the command line The line containing the error can be deleted later E endif E b b 1 E endwhile E print E a atl E endwhile E end Now that the procedure is entered type q to exit edit mode E q Ready To run the procedure type run mtable B run mtable Error 000 051 Ready
158. tement The FOR statement initializes the loop and the NEXT statement ends the loop The following is an example of a FOR NEXT loop FOR x 1 TO 3 PRINT Hi There NEXT x 2 13 Chapter 2 Getting Started This loop prints the string Hi There three times The first time BASIC encounters the FOR statement x equals 1 FOR x 1 BASIC executes the statement s within the loop which in this example is a PRINT statement When it reaches the NEXT statement it increments x and goes back to the FOR statement x now equals 2 so BASIC again executes the PRINT statement and goes to the NEXT statement Once again x is incremented X now equals 3 BASIC executes the PRINT statement and goes to the NEXT statement This time when the NEXT statement increments x x is greater than three Therefore BASIC does not execute the PRINT statement Instead it jumps to the statement that follows NEXT Using STEP Within a FOR NEXT Loop By default the NEXT statement increments the variable by one each time If you want to increment the variable by a value other than one you need to include a STEP declaration in the FOR statement For example FOR x 1 to 10 STEP 2 PRINT Hi There NEXT x The string Hi There is printed five times because each time BASIC comes to the NEXT statement x is incremented by two Therefore after the first pass through the loop x equals three instead of two The value to STEP may be a positive or negative
159. tements between the ELSE and ENDIF are skipped If the expression is evaluated to FALSE control is transferred to the first statement following the ELSE if present or to the statement immediately following the ENDIF FOR NEXT Chapter 11 Program Statements and Structure A special form of the IF statement transfers execution to the statement having a line number specified if the result of the expression is TRUE The line number follows immediately after THEN This is an implied GOTO statement Use this with caution as all GOTO statements should Examples IF a lt b THEN PRINT a is less than b PRINT as yas be sb ENDIF IF a lt b THEN PRINT a is less than b ELSE IF a b THEN PRINT a equals b ELSE PRINT a is greater than b ENDIF ENDIF IF payment lt balance THEN 400 Control Statement Syntax FOR lt var gt lt expr gt TO lt expr gt STEP lt expr gt NEXT lt var gt Function FOR NEXT creates a loop that usually executes a specified number of times while automatically increasing or decreasing a specified counter variable The first expression is evaluated and the result is stored in lt var gt lt var gt must be a simple integer or real variable The second expression is evaluated and stored in a temporary variable If you use STEP its expression is evaluated and used as the loop increment If the incremen
160. terminal and I O control Consult Using Personal OS 9 or Using Professional OS 9 for a detailed discussion of OS 9 standard commands SHELL requests OS 9 to create a new process This initially executes the shell which is the OS 9 command interpreter The shell can then call any program in the system The command line is evaluated and passed to the shell to be executed as a command line If no command line is specified BASIC is temporarily suspended and the shell process displays prompts and accepts commands in its normal manner When the shell process terminates BASIC becomes active again and resumes execution at the statement following the SHELL statement Examples SHELL copy filel file2 Sequential execution SHELL copy filel file2 amp Concurrent execution SHELL edt document Calling text editor SHELL asm source o obj spl amp Concurrent assembly SHELL Transfer control to SHELL END STOP Chapter 11 Program Statements and Structure End Procedure Execution Syntax END lt output list gt Function END stops execution of the procedure and returns to the calling procedure or to BASIC s command mode if it was the highest level procedure If an output list is specified END prints the list to standard output the same as a PRINT statement END is an executable statement You can use it several times in the same procedure END is optio
161. the name of the procedure This is followed by an asterisk signifying the current edit line in the procedure The last line displays the edit mode prompt E 2 1 Chapter 2 Getting Started Writing Your First Procedure 2 2 In edit mode the first character of each line is reserved for edit commands If you forget to type an edit command BASIC responds with the following prompt What The most important edit command is the Space character Placing a Space in the first character position saves the line of the procedure that immediately follows as a BASIC statement Important The edit commands are discussed later in this chapter There is also a chapter in the reference section which deals with the edit commands When writing your procedure you will probably want to receive and print data You can use the INPUT statement to receive data and the PRINT statement to print the data INPUT accepts data during the execution of a procedure The data is normally read from your terminal the standard input device PRINT outputs the text or the values given on the print line The output is normally sent to the terminal the standard output device Important Both input and output can be redirected This allows you to read data from a file or print a file to the printer For more information on redirecting input and output refer to either Using Personal OS 9 or Using Professional OS 9 With these two commands y
162. the output list to the standard output device path 1 the terminal unless you specify another path number Chapter 12 Files and Unified Input O utput The output list consists of one or more items separated by a comma or semicolon delimiter Each item can be a constant variable or expression of any basic type PRINT evaluates each item and converts the result to corresponding ASCII characters which are then displayed If the separator character following the item is a semicolon the next item is displayed without any intermediate spacing If a comma is used spaces are output so the next item starts at the next tab zone The tab zones are 16 characters in length starting at the beginning of the line If the line is terminated by a semicolon the usual carriage return following the output line is inhibited TAB lt expr gt can be used as an item in the output list This function causes the next item in the output list to start in the specified column lt expr gt If the output line is already past the desired tab position TAB is ignored A related function POS can be used in a program to determine the output position at any given time The output columns are numbered from one to a maximum of 255 The size of BASIC s output buffer varies according to stack size at the moment The PRINT USING form of this statement is described at the end of this chapter Examples PRINT value temp n 2 5 10cation n PRINT printe
163. the procedure 6 3 Chapter 6 Edit Mode String Oriented Editing 6 4 Most editor commands are string oriented which means that you can enter or change whole or partial lines without using line numbers String oriented editing is generally fast and convenient Because line numbers are not used the editor maintains an edit pointer to indicate which line is the present working location within the procedure String oriented commands work relative to this point The editor shows you the location of the edit pointer by displaying an asterisk at the left side of the program line where the edit pointer is presently located Moving the Edit Pointer Use the addition and subtraction commands to reposition the edit pointer Command Description lt number gt Moves backward lt number gt lines Moves to the beginning of the procedure Moves forward one line number Moves forward number lines Moves to the end of procedure The lt number gt indicates how many lines to move Backward means towards the first line of the procedure If the number is omitted one is used this is true of most edit commands A line consisting of a carriage return only moves the pointer forward one line which makes it easy to step through a program one line at a time Therefore the following commands all do the same thing CR CR 1 CR Inserting Lines The insert line function con
164. the specified place in your file The GET command retrieves the record The PUT and the GET statements have the same syntax PUT path no var data struct GET path no var data struct You can access data elements in a random access file individually The BASIC functions SEEK and SIZE can be used together to locate and place the file pointer at the beginning of any element Through proper use of these functions you can GET the record you want or PUT any record where you want it 3 5 Chapter 3 Program Construction Complex Data Types and Subroutines 3 6 Creating Files Before you can access a file you must first create it The syntax of the CREATE statement is as follows CREATE lt int or byte var gt lt path gt lt access mode gt For example the following command creates the file datafile in the h0 USR ELLEN directory CREATE A h0 usr ellen datafile WRITE This statement creates the specified file datafile and opens a path number to access it The CREATE statement assigns a path number to a variable The variable must be either an INTEGER or BYTE data type The access mode may be any of the following Access mode Description WRITE Only allows you to send WRITE PUT data to the file UPDATE Allows you to send and receive data WRITE PUT and READ GET EXEC Stores machine language code to be executed It is rarely used except by advanced BASIC progr
165. thlist You must have write permission for the file to be deleted See Using Personal OS 9 or Using Professional OS 9 for more information Examples DELETE D0 old junk nameS file55 DELETE name DELETE D2 name deletes file named D2 file55 Chapter 12 Files and Unified Input O utput SEEK 12 10 Seek to Address Syntax SEEK lt path num gt lt real expr gt Function SEEK Changes the file pointer address of a mass storage file which is the address of the next data byte s that are to be read or written Therefore SEEK is essential for random access of data in files using GET and PUT The lt path num gt may be an expression that specifies the path number of the file It must evaluate to a byte value The lt real expr gt specifies the desired file pointer address It must evaluate to an INTEGER or REAL value in the range 0 lt result lt 2 147 483 647 Any fractional part of the result is truncated Of course the actual maximum file size depends on the capacity of the device Although SEEK is normally used with random access files you can use it to rewind sequential files For example SEEK path 0 This is the same as a rewind or restore function This is the only form of the SEEK statement that is generally useful for files accessed by READ and WRITE These statements use variable length records
166. to be represented as integers are also stored in REAL format The following are examples of REAL constants Table 2 B REAL Constraints 1 0 9 8433218 1 95E 12 10000000000 01 999 000099 99999 9E 33 5655 34532 Numbers that do not have a decimal point and are in the INTEGER range are treated as INTEGER numbers BASIC also accepts integer constants in hexadecimal in the range 0 to FFFFFFFF Hex numbers must have a leading dollar sign The following are examples of INTEGER constants Table 2 C INTEGER Constraints BOOLEAN Constants The two legal BOOLEAN constants are TRUE and FALSE DIM flag state BOOLEAN flag TRUE state FALSE 2 9 Chapter 2 Getting Started Operators 2 10 STRING Constants STRING constants consist of a sequence of any characters enclosed by quotation marks To represent a quotation mark within the string use two consecutive quotation marks An empty string can also be represented by two consecutive quotation marks The following are examples of STRING constants This is a STRING constant wi a null string This is the real thing An operator combines or compares values of operands constants and variables Operators except negation take two operands and perform some operation to produce a result This result is generally the same type as the operands The table on the following page lists the operators available and the types they accept
167. to specify constants that correspond to the five basic data types Numeric constants can be either REAL or INTEGER If a number constant includes a decimal point or uses the E format exponential form BASIC stores the number in REAL format This is true even if the value could be represented by an INTEGER or BYTE data type For example 8 0 Therefore if you want to use a REAL constant include a decimal point This is sometimes done if all other values in an expression are of type REAL so BASIC does not have to do a time consuming type conversion at run time Numbers that do not have a decimal point but are too large to be represented as integers are also stored in REAL format The following are examples of REAL values 16 0 10 1234567 002 100000055 2 67E 12 458 9E 33 Boolean Constants String Constants Variables Chapter 9 Data Types and Data Structures Numbers that do not have a decimal point and are in the range of 2 147 483 648 to 2 147 483 647 are treated as INTEGER numbers BASIC also accepts integer constants in hexadecimal in the range 0 to FFFFFFFF Hexadecimal numbers must have a leading dollar sign The following are examples of INTEGER values 12 2771 49908 20 FEED 0A 0 The two legal boolean constants are TRUE and FALSE DIM flag state BOOLEAN flag TRUE state FALSE String constants consist of a sequence of any characters enclosed in quotation marks The binary val
168. tomatically by the ON ERROR command The mantissa covers the range from 1 0 through 1 99999999999999 in steps of 2 31 This means that REAL numbers can represent values on the number line about 0000000005 apart Operations which cause results between the representable points are rounded to the nearest representable number Floating point arithmetic is inherently inexact thus a sequence of operations can produce a cumulative error Proper rounding as implemented in BASIC reduces this effect but cannot eliminate it Programmers using comparisons on REAL quantities should use caution with strict comparisons or lt gt because the exact desired value may not occur during program execution The STRING Data Type A STRING is a variable length 0 or more sequence of characters A STRING of zero characters is called an empty STRING A variable may be defined as a STRING either explicitly DIM title STRING or implicitly by appending a dollar sign character to the variable name title My First Program The default maximum length allocated to each string is 32 characters but each string may be dimensioned less DIM A STRING 4 for memory savings or more DIM long STRING 2880 to allow long strings Important Strings are inherently variable length entities and dimensioning the storage for a string only defines the maximum length string which can be stored there 9 4 The BOOLEAN Data Type BYTE BYTE Chapter 9
169. ue of each character byte can be 1 to 255 Quotation marks can be included in the string by using two quotation marks in a row to represent one quotation mark The null string is important because it represents a string having no characters It is analogous to the numeric zero The following are STRING examples BASIC is a microcomputer language AABBCCDD wi a null string nw An older woman is wiser Each BASIC variable is local to the procedure where it is defined Local means that it is only known to the program statements within that procedure You can use the same variable name in several procedures and the variables will be completely independent If you want other procedures to be able to share a variable you must use the RUN and PARAM statements to pass the variable when a procedure calls another procedure Storage for variables is allocated from the BASIC workspace when the procedure is called You cannot force a variable to occupy a particular absolute address in memory When the procedure is exited variable storage is given back and the values stored in it are lost Procedures can call themselves this is referred to as recursion which causes another separate storage space for variables to be allocated 9 7 Chapter 9 Data Types and Data Structures Parameter Variables variables When a procedure is run all variables arrays and structures will have random values Your program must assign a
170. ues program execution at the next statement It may resume programs suspended by ctr1 c PAUSE statements BREAK command breakpoints or after non fatal run time errors Select Degree or Radian Units for Computation Syntax DEG RAD Function The DEG and RAD commands set a state flag The system uses this state flag to determine whether degrees or radians respectively should be used as the angle unit for trigonometric functions These commands only affect the procedure currently being debugged or run 8 3 Chapter 8 Debug Mode DIR LET LIST 8 4 Display Workspace Directory Syntax DIR lt path gt Function DIR displays the workspace procedure directory in the same way as the system mode DIR command Assignment Statement Syntax LET lt var gt lt expr gt Function The debug mode LET command is essentially the same as the BASIC LET program statement It allows the value of a procedure variable to be set to a new value using the result of the evaluated expression The variable names used in this command must be the same as in the original source program otherwise an error is generated LET does not work on user defined data structures List Current Procedure Syntax LIST Function LIST displays a formatted source listing of the suspended procedure with Icode addresses An asterisk is printed to the left of the statement where the procedure is suspended You can only li
171. ures 2 0 000 eee ee een nee Line Numbers and the GOTO Statement Putting It All Together 0 0 0 0 eee Program Construction Chapter 3 Complex Data Types and Introduction sos e ep ES ae EES Ae SSE ws ERS ee ES Subroutines JATTAVS oi acd Betis oink tnde beanie ae Mane Dae nek RR n waa The TYPE Declaration 0 0 0 0 ccc eee eens External Files 22 ae erc toon o o ibe apnoea RU SORTS ego ood SUBTOUTIMES ux s eau UR Ra ee CR EU dank RON RUE ahead anal dual Calling Procedures nr ed ep x c a idea dean Re Command Line Parameters 0 0 0 0 ccc ee eee Formatted Output The PRINT USING Statement Program Optimization Chapter 4 General Execution Performance of BASIC 005 Optimum Use of Numeric Data Types 0 0 00 ee ee ee Looping Quickly i esce cs Ut epe m eee ote E arene eben ea Optimum Use of Arrays and Data Structures 0004 The PACK Command ensec eterne ERR hc EU RE Eliminating Constant Expressions and Sub Expressions Fast Input and Output Functions 0 0 0 cece eee eee Professional Programming Techniques lllslleleleess Table of Contents 0S 9 BASIC User Manual SECTION2 BASIC REFERENCE GUIDE System Mode Chapter 5 BYE or eof character 0 0 0 ccc ee eens CHD CHX oc us eee bet he eee ed me eee ee e des aed alee DIGITS 44 3a sace bee haa RG eda
172. valid ASCII characters The READ and WRITE commands perform format conversion similar to that done automatically in INPUT and PRINT commands A sequential file contains record delimiter characters carriage return which separate the data created by different WRITE operations Each WRITE command sends a complete sequential file record which is a variable number of characters terminated by a carriage return Each READ reads all characters up to the next carriage return A random access file sends and receives data in binary form by the PUT or GET statements exactly as it is internally represented in BASIC This minimizes both the time involved in converting the data to and from ASCII representation and reducing the file space required to store the data You can PUT and GET individual bytes or a substructure of many bytes in a complex structure The GET structure statement recovers the number of bytes associated with that type of structure You can move to a particular byte in a random access file by using SEEK to find it and using PUT or GET sequentially from that point Chapter 12 Files and Unified Input O utput I O Paths In general SEEK path 0 is equivalent to the REWIND used in some forms of BASIC Because the random access file contains no record separators to indicate the size of particular elements of the file use the SIZE function to determine the size of a single element then use SEEK to move to the desired element within
173. ve UMERIC Multiplication UMERIC UMERIC Division UMERIC UMERIC Addition UMERIC UMERIC Subtraction UMERIC UMERIC NOT Logical Negation BOOLEAN BOOLEA AND Logical AND BOOLEAN BOOLEA OR Logical OR BOOLEAN BOOLEA XOR Logical EXCLUSIVE OR BOOLEAN BOOLEA Concatenation STRING STRING Equal to ANY BOOLEA lt gt 0r gt lt Not equal to ANY BOOLEA lt Less than NUMERIC STRING 1 BOOLEA zr lt Less than or Equal NUMERIC STRING 2 BOOLEA gt Greater than NUMERIC STRING 3 BOOLEA gt 0r gt Greater than or Equal NUMERIC STRING 4 BOOLEA When comparing strings the ASCII collating sequence is used so that0 lt 1 9 A B a lt Z lt a lt b lt lt Z Important NUMERIC refers to either BYTE INTEGER or REAL types Operator Precedence Chapter 10 Expressions Operators and Functions Operators have precedence This means they are evaluated in a specific order Parentheses can override natural precedence However the compiler may remove extraneous parentheses The legal operators are listed here in precedence order from highest to lowest Precedence Operator Highest Precedence NOT negate xk FEES Lowest P recedence OR XOR Operators of equal precedence are shown on the same line and are evaluated left to right in expressions The only exception to this rule is exponentiation which is evaluated right to left Raisi
174. ware and or other parties Unauthorized distribution of software may cause damages far in excess of the value of the copies involved For additional copies of this software and or documentation or if you have questions concerning the above notice the documentation and or software please contact your OS 9 supplier OS 9 Personal OS 9 Professional OS 9 Basic09 and Microware Basic are trademarks of Microware Systems Corp UNIX is a trademark of Bell Laboratories Microware Systems Corporation e 1900 N W 114th Street Des Moines Iowa 50325 7077 Phone 515 224 1929 Microware BASIC Features Preface Introduction Introduction Microware BASIC is an enhanced structured Basic language programming system It was created for the 68000 Microprocessor In addition to the standard BASIC language statements and functions Microware BASIC includes many of the useful elements of the PASCAL programming language This allows programs to be modular well structured and use sophisticated data structures It permits full access to almost all of the OS 9 operating system commands and functions so it can be used as a systems programming language Microware BASIC is unusual in that it is an interactive compiler It has the fast execution speed typical of compiler languages and the ease of use and memory space efficiency typical of interpreter languages Microware BASIC includes a powerful text editor a multi pass compiler a run time inte
175. was used PRINT prin c The extra space was added to separate the integers being printed A similar result can be obtained by using the PRINT USING statement PRINT USING I3 prin c This formats each integer in a three space print field 13 The integers are right justified gt You should use some caution when formatting While a leading sign is not printed when positive space for it must be allowed I3 only prints two digit integers A full explanation of the PRINT USING statement and each of the format types can be found in the reference section of this manual Chapter 3 Program Construction Complex Data Types and Subroutines NOTES General Execution Performance of BASIC Program Optimization When you run your procedures Microware s BASIC compiler makes multiple passes through the code The compiler produces a compressed and optimized low level I code for execution Compared to other BASIC languages program storage is greatly decreased and execution speed is increased High level language interpreters have a general reputation for slowness This is partly because traditional BASIC interpreters compile from text as they run and other BASIC interpreters must perform table searching during execution Microware BASIC however is kept at a powerful level so that there is little performance difference between the execution of I code and straight machine language instructions Instead a single
176. weight READ 0 height weight 12 11 Chapter 12 Files and Unified Input O utput WRITE 12 12 Write Data Syntax WRITE lt path num output list Function WRITE Writes data in ASCII character format on a file device The first expression specifies the number of a path that was previously opened by OPEN or CREATE in WRITE or UPDATE mode The output list consists of one or more expressions separated by commas Each expression can evaluate to any expression type The result is then converted to an ASCII character string and written on the specified path beginning at the present file pointer which is updated as data is written If the output list has more than one item ASCII null characters 00 are written between each output string The last item is followed by a carriage return character Important This statement creates variable length ASCII records Examples WRITE outpath cat dog mouse WRITE xfile LEFTS A n count 2 GET PUT Chapter 12 Files and Unified Input O utput Read and Write Data Records Syntax lt path num gt lt struct name gt E PUT lt path num gt lt struct name gt Function GET and PUT read and write fixed size binary data records to files or devices respectively These are the primary I O statements used for random access input and output The path number may be an expression which is evaluated and used as the
177. xpression evaluates to FALSE when first executed Examples WHILE a lt b DO is equivalent to 100 IF a gt b THEN 500 PRINT a PRINT a a atl a atl ENDWHILE GOTO 100 500 REM DIM yes BOOLEAN yes TRUE WHILE yes DO PRINT yes yes POS 50 DWHILE EM reverse the letters in word R backward W T W PUT word HILE LEN word gt 0 DO backward backward RIGHTS word 1 words LEFTS words LEN word 1 ENDWHILE words backward PRINT words Chapter 11 Program Statements and Structure REPEAT UNTIL Control Statement Syntax REPEAT lt statements gt UNTIL lt bool expr gt Function This loop tests its control expression at the bottom of the loop The statement s within the loop are executed until the result of lt bool expr gt is TRUE The body of the loop is always executed at least one time Examples x 0 is the same as x 0 REPEA 100 PRINT x PRINT x x x 1 x x 1 IF X lt 10 THEN 100 UNTIL x gt 10 compute factorial n temp 1 INPUT Factorial of what number n REPEAT temp temp n n n 1 UNTIL n lt 1 0 PRINT The factorial is temp LOOP ENDLOOP EXITIF ENDEXIT Chapter 11 Program Statements and Structure Control Statement Syntax LOOP lt statements gt ENDLOOP EXITIF lt bool expr gt THEN
178. y Concerning This Manual Preface Introduction This manual is divided into two parts the BASIC Tutorial and the BASIC Reference Manual The tutorial section is written for beginning programmers having little experience with Pascal or other high level languages Beginning programmers should work through the examples given to help familiarize themselves with Microware BASIC control structure Readers having adequate programming skills are urged to browse the tutorial for a feeling of the Microware BASIC environment A complete index is provided for easy use of the reference section In this manual Microware BASIC is referred to as BASIC unless making reference to other BASIC languages iii Table of Contents 05 9 BASIC User Manual SECTION1 THE BASIC TUTORIAL Overview Chapter 1 ntfodUCtlOh o eee eid sae dela Sele RE RE Getting Started ecs scie cot euii ende eda bdo ee REA EUR ERR a Fundamental Commands Getting Started Chapter 2 Naming Your Procedure 0 cece eee eee nee Writing Your First Procedure 0 0 0 cece eee eee The DIM Statement Declaring Variables 004 Variable Data Types oone coa seceteni eent ata DEN EEEE EAR eh Constants vxo eode e Led ae eee DUO etin e Ados Operators oci va Hae tsa Beau rm aul Pg deas aider e cio urs Conditional Control The IE THEN Structure Looping Statements sleeeleeee eh Editing Your Proced
179. y gt option to specify more memory when you enter BASIC For example to call BASIC with 16K of memory enter the following command basic 16k PACK Compressing Procedures The PACK command compresses a BASIC procedure and places it in your current execution directory Depending on the number of comments line numbers etc packed procedures execute from 10 to 30 faster than unpacked procedures BASIC loads the packed procedure when you try to run it after it has been packed The following is an example of using PACK B PACK exloop Important Before you PACK a procedure always SAVE it first You cannot load a packed file into your workspace Packing a procedure removes it from your workspace SAVE Saving Procedures When you exit BASIC all unsaved procedures are erased The SAVE command allows you to save your programs You can use SAVE in a number of ways Command Description Type SAVE by itself BASIC creates a file with the name of the last edited or run procedure in your current data directory If a file already has this name BASIC returns the prompt Rewrite If you respond y for yes it replaces the file previously stored in that space with the new procedure OS 9 does not allow two files with the same name in the same directory By answering n for no you cancel the SAVE command without changing the procedure in your workspace or the file in your directory Type SAVE gt and a file This saves the proc

Download Pdf Manuals

Related Search

Related Contents

  Cocina Instalación y uso Fogão Instalação e uso K6G21S/P  取扱説明書  Anthro Fit Adjusta Unit  U s e r M anual - Advanced Micro Controls Inc  取 扱 説 明 書 - hhstyle.com  AN10908 - NXP Semiconductors  Husky HD12120 Use and Care Manual  SpeakerCraft BB50S AV receiver    

Copyright © All rights reserved. Failed to retrieve file