Introduction to the Microsoft BASIC Interpreter Special Characters Variable Type Declaration Chars Commands Edit Mode Subcommands Program Statements (except I/O) PRINT USING Format Field Specifiers Input/Output Statements Operators Arithmetic Functions String Functions I/O and Special Functions Interpreter Error Codes Introduction to the Microsoft BASIC Compiler Compiler Commands and Switches Compiler Error Messages :Introduction to the Microsoft BASIC Interpreter Thió HELĐ Filĺ ió deriveä froí thĺ "Microsofô BASIĂ Referencĺ Book"¬ Ť anä iô ió divideä intď twď partó -- onĺ coverinç thĺ Interpreteň anä thĺ Ť otheň coverinç thĺ Compiler® Thesĺ programó procesó programó writteî iî Ť almosô exactlů thĺ samĺ languagĺ -- Microsofô BASIC» therĺ arĺ minoň Ť differenceó betweeî thĺ two¬ however¬ anä thesĺ arĺ discusseä iî thĺ filĺ Ť under the Compiler Introduction. The MBASIC (Microsoft BASIC) Interpreter is invoked as follows -- MBASIC [][/F:<# files>][/M:] Ić at terminal ^H Deletes last char typed ^I Tab (every 8) ^O Halts/resumes program output ^R Retypes the line currently being typed ^S Suspends program execution ^Q Resumes execution after ^S ^U,^X Deletes line being typed Ends every line being typed in Breaks a logical line into physical lines Deletes last char typed Escapes Edit Mode Subcommands . Current line for EDIT, RENUM, DELETE, LIST, LLIST commands &O,& Prefix for Octal Constant &H Prefix for Hex Constant : Separates statements typed on the same line ? Equivalent to PRINT statement Š:Variable Type Declaration Characters $ String 0 to 255 chars % Integer -32768 to 32767 ! Single Precision 7.1 digit floating point # Double Precision 17.8 digit floating point :Commands Command Syntax Function AUTO AUTO [line][,inc] Generate line numbers CLEAŇ CLEAŇ [,[exp1][,exp2]Ý Cleaň prograí variables» Exp± setó Ť enä oć memorů anä Exp˛ setó amounô Ť of stack space CONT CONT Continue program execution DELETE DELETE [[start][-[end]]] Delete program lines EDIT EDIT line Edit a program line FILES FILES [filename] Directory LIST LIST [line[-[line]]] List program line(s) LLIST LLIST [line[-[line]]] List program line(s) on printer LOAD LOAD filename[,R] Load program; ,R means RUN MERGE MERGE filename Merge prog on disk with that in mem NAME NAME old AS new Change the name of a disk file NEW NEW Delete current prog and vars NULL NULL exp Set num of s after each line RENUM RENUM [[new][,[old][,inc]]] Renumber program lines RESET RESET Init CP/M; use after disk change Command Syntax Function RUN RUN [line number] Run a prog (from a particular line) RUN filename[,R] Run a prog on disk SAVĹ SAVĹ filename[,Á oň ,PÝ Savĺ proç ontď disk» ,Á saveó proç Ť in ASCII and ,P protects file SYSTEM SYSTEM Return to CP/M TROFF TROFF Turn trace off TRON TRON Turn trace on WIDTČ WIDTČ [LPRINTÝ exđ Seô terí oň printeň carriagĺ width» Ť default is 80 (term) and 132 (prin) :Edit Mode Subcommands A Abort -- restore original line and restart Edit nCc Change n characters nD Delete n characters E End edit and save changes; don't type rest of line Hstr Delete rest of line and insert string Istr Insert string at current pos nKc Kill all chars up to the nth occurrance of c L Print the rest of the line and go to the start of the line Q Quit edit and restore original line nSc Search for nth occurrance of c Xstr Goto the end of the line and insert string Backspace over chars; in insert mode, delete chars End edit and save changes :Program Statements (except I/O) Statement Syntax Function CALL CALL variable [(arg list)] Call assembly or FORTRAN routine CHAIN CHAIN [MERGE] filename [,[line exp][,ALL][,DELETE range]] Calě á prograí anä pasó variableó tď it» MERGĹ witč ASCIÉ Ť fileó allowó overlays» starô aô linĺ exđ ić given» ALĚ meanó Ť alě variableó wilě bĺ passeä (otherwisĺ COMMOÎ only)» DELETĹ Ť allows deletion of an overlay before CHAIN is executed COMMON COMMON list of vars Pass vars to a CHAINed prog DEF DEF FNx[(arg list)]=exp Arith or String Function DEF USRn=address Define adr for nth assembly routine DEFINT range(s) of letters Define default var type INTeger DEFSNG " " " " " " " Single DEFDBL " " " " " " " Double DEFSTR " " " " " " " String DIM DIM list of subscripted vars Allocate arrays END END Stop prog and close files ERASE ERASE var [,var ... ] Release space and var names ERROR ERROR code Generate error code/message FOR FOR var=exp TO exp [STEP exp] FOR loop Statement Syntax Function GOSUB GOSUB line number Call BASIC subroutine GOTO GOTO line number Branch to specified line IF/GOTO IF exp GOTO line [ELSE stmt ... ] IF exp <> 0 then GOTO IF/THEN IF exp THEN stmt[:stmt] [ELSE stmt ... ] IF exp <> 0 then ... else ... LET [LET] var=exp Assignment MID¤ MID$(string,n[,m])=string˛ Replacĺ á portioî oć strinç witč Ť string2; start at pos n for m chars NEXT NEXT var[,var ... ] End FOR ON ERROR ON ERROR GOTO line Error trap subroutine GOTO ON/GOSUB ON exp GOSUB line[,line] Computed GOSUB ON/GOTO ON exp GOTO line[,line] Computed GOTO Statement Syntax Function OPTION OPTION BASE n Min val for subscripts (n=0,1) BASE OUT OUT port,byte Output byte to port POKE POKE address,byte Memory put RANDOMIZE RANDOMIZE [exp] Reseed random number generator REM REM any text Remark -- comment RESTORE RESTORE [line] Reset DATA pointer RESUME RESUME or RESUME 0 Return from ON ERROR GOTO RESUME NEXT Return to stmt after error line RESUME line Return to specified line RETURN RETURN Return from subroutine STOP STOP Stop prog and print BREAK msg WAIÔ WAIÔ prot,mask[,selectÝ Pausĺ untiě inpuô porô [XOŇ selectÝ Ť AND mask <> 0 WHILE/ WHILE exp stmts ... WEND Execute stmts as long as exp is T WEND :PRINT USING Format Field Specifiers Numeric Specifiers Specifier Digits Chars Definition # 1 1 Numeric field . 0 1 Decimal point + 0 1 Print leading or trailing sign - 0 1 Trailing sign (- if neg, otherwise) ** 2 2 Leading asterisk $¤ ± ˛ Floatinç dollaň sign» placeä iî fronô oć leading digit **$ 2 3 Asterisk fill and floating dollar sign , 1 1 Use comma every three digits ^^^^ 0 4 Exponential format _ 0 1 Next character is literal String Specifiers Specifier Definition ! Single character // Character field; width=2+number of & Variable length field :Input/Output Statements Statement Syntax/Function CLOSE CLOSE [[#]f[,[#]f ... ]] Close disk files; if no arg, close all DATA DATA constant list List data for READ statement FIELD FIELD [#]f,n AS string var [,n AS string var ...] Define fields in random file buffer GET GET [#]f[,record number] Read a record from a random disk file INPUT INPUT [;] [prompt string;] var [,var ...] INPUT [;] [prompt string,] var [,var ...] Reaä datá froí thĺ terminal» leadinç semicoloî suppresseó echď Ť oć // LINE INPUT #f,string var Read an entire line from a disk file LSET LSET field var=string exp Storĺ datá iî randoí filĺ buffeň left-justifieä oň left-justifů Ť a non-disk string in a given field OPEN OPEN mode,[#] f,filename Open a disk file; mode must be one of -- I = sequential input file O = sequential output file R = random input/output file Statement Syntax/Function PRINT PRINT [USING format string;] exp [,exp ...] Print data at the terminal using the format specified PRINT #f, [USING format string;] exp [,exp ...] Write data to a disk file LPRINT [USING format string;] var [,var ...] Write data to a line printer PUT PUT [#] f [,record number] Write data from a random buffer to a data file READ READ var [,var ...] Read data from a DATA statement into the specified vars RSET RSET field var = string exp Storĺ datá iî á randoí filĺ buffeň righô justifieä oň righô Ť justify a non-disk string in a given field WRITE WRITE [list of exps] Output data to the terminal WRITE #f, list of exps Output data to a sequential file or a random field buffer :Operators Symbol Function = Assignment or equality test - Negation or subtraction + Addition or string concatenation * Multiplication / Division (floating point result) ^ Exponentiation \ Integer division (integer result) MOD Integer modulus (integer result) NOT One's complement (integer) AND Bitwise AND (integer) OR Bitwise OR (integer) XOR Bitwise exclusive OR (integer) EQV Bitwise equivalence (integer) IMP Bitwise implication (integer) =,>,<, Relational tests (TRUE=-1, FALSE=0) <=,=<, >=,=>, <> The precedence of operators is -- 1. Expressions in parentheses 8. Relational Operators 2. Exponentiation 9. NOT 3. Negation (Unary -) 10. AND 4. *,/ 11. OR 5. \ 12. XOR 6. MOD 13. IMP 7. +,- 14. EQV :Arithmetic Functions Function Action ABS(exp) Absolute value of expression ATN(exp) Arctangent of expression (in radians) CDBL(exp) Convert the expression to a double precision number CINT(exp) Convert the expression to an integer COS(exp) Cosine of the expression (in radians) CSNG(exp) Convert the expression to a single precision number EXP(exp) Raises the constant E to the power of the expression FIX(exp) Returns truncated integer of expression FRE(exp) Gives memory free space not used by MBASIC INT(exp) Evaluates the expression for the largest integer LOG(exp) Gives the natural log of the expression RND[(exp)] Generates a random number exp <0 seeds new sequence exp =0 returns previous number exp >0 or omitted returns new random number Function Action SGN(exp) 1 if exp >0 0 if exp =0 -1 if exp <0 SIN(exp) Sine of the expression (in radians) SQR(exp) Square root of expression TAN(exp) Tangent of the expression (in radians) :String Functions Function Action ASC(str) Returns ASCII value of first char in string CHR$(exp) Returns a 1-char string whose char has ASCII code of exp FRE(str) Returns remaining memory free space HEX$(exp) Converts a number to a hexadecimal string INPUT$(length [,[#]f]) Returnó á strinç oć lengtč charó reaä froí consolĺ oň froí á Ť disk file; characters are not echoed INSTR([exp,]str1,str2) Returnó thĺ firsô positioî oć thĺ firsô occurrencĺ oć str˛ Ť in str1 starting at position exp LEFT$(str,len) Returns leftmost length chars of the string expression LEN(str) Returns the length of a string MID$(string,start[,length]) Returnó charó froí thĺ middlĺ oć thĺ strinç startinç aô thĺ Ť positioî specifieä tď thĺ enä oć thĺ strinç oň foň lengtč Ť characters Function Action OCT$(exp) Converts an expression to an Octal string RIGHT$(str,len) Returns rightmost length chars of the string expression SPACE$(exp) Returns a string of exp spaces STR$(exp) Converts a numeric expression to a string STRING$(length,str) Returnó á strinç lengtč lonç containinç thĺ firsô chaň oć Ť the str STRING$(length,exp) Returnó á strinç lengtč lonç containinç charó witč numeriă Ť value exp VAL(str© Convertó thĺ strinç representatioî oć á numbeň tď itó Ť numeric value :I/O and Special Functions Function Action CVI(str) Converts a 2-char string to an integer CVS(str) Converts a 4-char string to a single precision number CVD(str) Converts an 8-char string to a double precision number EOF(f) Returns TRUE (-1) if file is positioned at its end ERL Error Line Number ERR Error Code Number INP(port) Inputs a byte from an input port LOC(f© Returnó nexô recorä numbeň tď reaä oň writĺ (randoí file© oň Ť number of sectors read or written (sequential file) LPOS(n) Returns carriage position of line printer (n is dummy) MKI$(value) Converts an integer to a 2-char string MKS$(value) Converts a single precision values to a 4-char string MKD$(value) Converts a double precision value to an 8-char string Function Action PEEK(exp) Reads a byte from memory location specified by exp POS(n) Returns carriage position of terminal (n is dummy) SPC(exp) Used in PRINT statements to print spaces TAB(exp) Used in PRINT statements to tab to specified position USR[n](arg) Calls the user's machine language subroutine with the arg VARPTR(var© Returnó addresó oć vaň iî memorů oň zerď ić vaň haó noô beeî Ť assigned a value VARPTR(#f© Returnó thĺ addresó oć thĺ disë I/Ď buffeň assigneä tď filĺ Ť number :Interpreter Error Codes Code Error Code Error 1 NEXT without FOR 14 Out of string space 2 Syntax error 15 String too long 3 RETURN without GOSUB 16 String formula too complex 4 Out of data 17 Can't continue 5 Illegal function call 18 Undefined user function 6 Overflow 19 No RESUME 7 Out of memory 20 RESUME without error 8 Undefined line 21 Unprintable error 9 Subscript out of range 22 Missing operand 10 Redimensioned array 23 Line buffer overflow 11 Division by zero 26 FOR without NEXT 12 Illegal direct 29 WHILE without WEND 13 Type mismatch 30 WEND without WHILE Disk Errors -- Code Error Code Error 50 Field overflow 58 File already exists 51 Internal error 61 Disk full 52 Bad file number 62 Input past end 53 File not found 63 Bad record number 54 Bad file mode 64 Bad file name 55 File already open 66 Direct statement in file 57 Disk I/O error 67 Too many files :Introduction to the Microsoft BASIC Compiler Thĺ followinç direcô modĺ commandó arĺ NOÔ implementeä oî thĺ compileň Ť and will generate an error message -- AUTO CLEAR CLOAD CSAVE CONT DELETE EDIT LIST LLIST RENUM COMMON SAVE LOAD MERGE NEW ERASE Thĺ followinç statementó arĺ useä differentlů witč thĺ compileň thaî Ť with the interpreter (refer to the manual for details) -- CALL DEFINT DEFSNG DEFDBL DEFSTR DIM ERASE END ON ERROR GOTO RESUME STOP TRON TROFF USRn :BASIC Compiler Commands and Switches The compiler is invoked by the BASCOM command; it may be called by -- BASCOM or BASCOM command line where "command line" is -- [dev:][obj file][,[dev:][lst file]]=[dev:]source file[/switch ...] Ić jusô BASCOÍ ió used¬ thĺ useň wilě bĺ prompteä witč aî asterisk¬ Ť after which he should enter the command line. Switches -- /E Use this switch if ON ERROR GOTO with RESUME is used /Ř Usĺ thió switcč ić OÎ ERROŇ GOTĎ witč RESUME¬ RESUMĹ 0¬ oň RESUMĹ NEXÔ Ť is used /N Do not list generated object code /D Generate debug/checking code at runtime /S Write quoted strings of more than 4 chars as they are encountered /4 Recognize Microsoft 4.51 BASIC Interpreter conventions /Ă Relař linĺ numberinç constraints» lineó neeä noô bĺ numbereä Ť sequentially; /4 and /C may not be used together /Z Use Z80 opcodes :BASIC Compiler Error Messages Compile-Time Fatal Errors SN Syntax error OM Out of memory SQ Sequence error TM Type mismatch TC Too complex BS Bad subscript LL Line too long UC Unrecognizable command OV Math overflow /0 Division by zero DD Array already dim'ed FN FOR/NEXT error FD Function already def UF Function not defined WE WHILE/WEND error /E Missing /E switch /X Missing /X switch Compile-Time Warning Errors ND Array not dimensioned SI Statement ignored Run-Time Error Messages 2 Syntax error 52 Bad file number 3 RETURN without GOSUB 53 File not found 4 Out of data 54 Bad file mode 5 Illegal function call 55 File already open 6 Floating/Integer ovfl 57 Disk I/O error 9 Subscript out of range 58 File already exists 11 Division by zero 61 Disk full 14 Out of string space 62 Input past end 20 RESUME without error 63 Bad record number 21 Unprintable error 64 Bad filename 50 Field overflow 67 Too many files 51 Internal error