********************************************************************** * * VTL-2 Source Re-Creation * This source file was created by (unknown) by keying in the * source code provided in the VTL-2 manual. This required * translating the unusual syntax of the cross-assembler used * by the original authors into a more conventional Motorola * assembler format. The output of this assembly then found its * way to many Altair 680 web archives as "the" S-Record file * for VTL-2. * * However, in June of 2022, it was discovered that this source * file contained two errors: * * 1) The operand of the suba instruction at label eval5 * should have been #'= instead of '=. This error caused * most relational operations to fail. * * 2) The operand of the cmpb instruction in the evalu routine * should have been #'$ instead of #$. This caused direct * ASCII output through the $ device to fail. * * These bugs were found, fixed, and the source file cleaned up * by Mike Douglas in June of 2022. The output of this source * file now exactly matches the hex bytes in the listing provided * in the VTL-2 manual. * ********************************************************************** * VTL-2 * v-3.6 * 9-23-76 * By Gary Shannon * & Frank McCoy * Copyright 1976, The Computer Store * Define locations in monitor INCH equ $FF00 POLCAT equ $FF24 OUTCH equ $FF81 * Misc defines LINLEN equ 72 input line length CR equ $0D LF equ $0A * Set aside four bytes for user defined * interrupt routine if needed org 0 zero rmb 4 interrupt vector at rmb 2 cancel & cr * General purpose storage vars rmb 52 variables (A-Z) brak rmb 2 [ open bracket save10 rmb 2 \ backslash brik rmb 2 ] close bracket up rmb 2 ^ up arrow save11 rmb 2 _ underscore save14 rmb 2 space excl rmb 2 ! bang (return address) quote rmb 2 " double quote (string literals) dolr rmb 2 # pound sign (line number) dollar rmb 2 $ dollar sign (char i/o) remn rmb 2 % percent (remainder after divide) ampr rmb 2 & ampersand (end of program) quite rmb 2 ' single quote (random number) paren rmb 2 ( open paren parin rmb 2 ) close paren star rmb 2 * asterisk (end of memory) plus rmb 2 + plus sign coma rmb 2 , comma mins rmb 2 - minus perd rmb 2 . period slash rmb 2 / forward slash save0 rmb 2 0 zero save1 rmb 2 1 one save2 rmb 2 2 two save3 rmb 2 3 three save4 rmb 2 4 four save5 rmb 2 5 five save6 rmb 2 6 six save7 rmb 2 7 seven save8 rmb 2 8 eight save9 rmb 2 9 nine coln rmb 2 : colon (array operator) semi rmb 2 ; semi-colon (no cr/lf on string print) less rmb 2 < less than eqal rmb 2 = equal sign grat rmb 2 > greater than or equal decbuf rmb 4 lastd rmb 1 delim rmb 1 linbuf rmb LINLEN+1 reserve line length + 1 bytes org $F1 stack rmb 15 space for monitor mi rmb 4 monitor interrupt vectors nmi rmb 4 prgm equ * user program starts here org $FC00 start lds #stack entry point clra ldx #okm bsr strgt loop clra staa dolr staa dolr+1 jsr cvtln returns line # in b:a bcc stmnt no line # then exec bsr exec beq start loop2 bsr find find line eqstrt beq start if end then stop ldx 0,x load real line # stx dolr save it ldx save11 get line inx bump past line # inx inx bsr exec execute it beq loop3 if zero continue ldx save11 find line # ldx 0,x get it cpx dolr has it changed? beq loop3 if not get nexr inx increment old line # stx excl save for return bra loop2 continue loop3 bsr fnd3 find next line bra eqstrt continue exec stx save7 execute line jsr var2 inx skip ldaa 0,x get first term bsr evil outx ldx dolr rts evil cmpa #'" double quote bne evalu inx strgt jmp strng to print it * Insert line into program, new line # in b:a stmnt stx save8 save line # staa dolr stab dolr+1 ldx dolr bne skp2 if line # > 0 * List program ldx #prgm list program lst2 cpx ampr end of program beq eqstrt stx save11 line # for cvdec ldaa 0,x ldab 1,x jsr prnt2 ldx save11 inx inx jsr pntmsg jsr crlf bra lst2 nxtxt ldx save11 get pointer inx bump past line# lookag inx find end of line tst 0,x bne lookag inx rts find ldx #prgm find line # fnd2 stx save11 cpx ampr beq rts1 ldaa 1,x suba dolr+1 ldaa 0,x sbca dolr bcc set fnd3 bsr nxtxt bra fnd2 set ldaa #$FF set not equal rts1 rts evalu jsr eval evaluate line pshb psha ldx save7 jsr convp pula cmpb #'$ string? bne ar1 pulb jmp OUTCH then print it ar1 subb #'? print? beq prnt then do it incb machine language? pulb bne ar2 swi then interrupt ar2 staa 0,x store new value stab 1,x addb quite randomizer adca quite+1 staa quite stab quite+1 rts * Continue inserting line into program, new line # in x skp2 bsr find find line beq insrt if not there ldx 0,x then insert cpx dolr new line bne insrt bsr nxtxt setup registers lds save11 for delete delt cpx ampr delete old line beq fitit ldaa 0,x psha inx ins ins bra delt fitit sts ampr store new end insrt ldx save8 count new line length ldab #3 tst 0,x beq gotit if no line then stop cntln incb inx tst 0,x bne cntln open clra calculate new end addb ampr+1 adca ampr staa save10 stab save10+1 subb star+1 sbca star bcc rstrt if too big then stop ldx ampr lds save10 sts ampr inx slide dex ldab 0,x pshb cpx save11 bne slide don lds dolr store line # sts 0,x lds save8 get new line des movl inx pulb stab 1,x bne movl gotit lds #stack jmp loop rstrt jmp start prnt pulb print decimal prnt2 ldx #decbuf convert to decimal stx save4 ldx #pwrs10 cvd1 stx save5 ldx 0,x stx save6 ldx #save6 jsr divide psha ldx save4 ldaa save2+1 adda #'0 staa 0,x inx stx save4 ldx save5 pula inx inx tst 1,x bne cvd1 ldx #decbuf-1 com 5,x zero suppress zrsup inx ldab 0,x cmpb #'0 beq zrsup com lastd pntmsg clra zero for delim strtms staa delim store delimiter outmsg ldab 0,x general purpose print inx cmpb delim beq ctlc jsr OUTCH bra outmsg ctlc jsr POLCAT poll for character bcc rts2 bsr inch2 cmpb #3 ctrl-c? beq rstrt inch2 jmp INCH strng bsr strtms print string literal ldaa 0,x cmpa #'; beq outd crlf2 jmp crlf eval bsr getval evaluate expression nxtrm psha ldaa 0,x end of line? beq outn cmpa #') outn pula beq outd bsr term ldx save0 bra nxtrm term psha get value pshb ldaa 0,x psha inx bsr getval staa save3 stab save3+1 stx save0 ldx #save3 pula pulb cmpa #'* see if * bne eval2 pula multiply multip staa save2 stab save2+1 2's complement ldab #16 stab save1 clra clrb mult lsr save2 ror save2+1 bcc noad multi bsr add noad asl 1,x rol 0,x dec save1 bne mult loop till done rts2 rts getval jsr cvbin get value bcc outv cmpb #'? of literal bne var stx save9 or input jsr inln bsr eval ldx save9 outd inx outv rts var cmpb #'$ or string bne var1 bsr inch2 clra inx rts var1 cmpb #'( bne var2 inx bra eval var2 bsr convp or variable ldaa 0,x or array element ldab 1,x ldx save6 load old index rts array bsr eval locate array element aslb rola addb ampr+1 adca ampr bra pack convp ldab 0,x get location inx pshb cmpb #': beq array of variable or clra andb #$3F addb #2 aslb pack stx save6 store old index staa save4 stab save4+1 ldx save4 load new index pulb rts eval2 cmpa #'+ addition bne eval3 pula add addb 1,x adca 0,x rts eval3 cmpa #'- subtraction bne eval4 pula subtr subb 1,x sbca 0,x rts eval4 cmpa #'/ see if it's divide bne eval5 pula bsr divide staa remn stab remn+1 ldaa save2 ldab save2+1 rts eval5 suba #'= see if equal test bne eval6 pula bsr subtr bne noteq tstb beq eql noteq ldab #$FF eql bra combout eval6 deca see if less than test pula beq eval7 sub2 bsr subtr rolb comout clra andb #1 rts eval7 bsr sub2 gt test combout comb bra comout pwrs10 fdb 10000,1000,100,10,1 * Divide a:b by *x, result in save2, remainder in a:b divide clr save1 divide 16-bits got inc save1 asl 1,x rol 0,x bcc got ror 0,x ror 1,x clr save2 clr save2+1 div2 bsr subtr a:b := a:b - *x bcc ok bsr add a:b := a:b + *x clc fcb $9C cpx trick ok sec rol save2+1 rol save2 dec save1 beq done lsr 0,x ror 1,x bra div2 tstn ldab 0,x test for numeric cmpb #'9+1 bpl notdec cmpb #'0 bge done notdec sec rts done clc dun rts cvtln bsr inln cvbin bsr tstn convert to binary bcs dun cont clra clrb cbloop addb 0,x adca #0 subb #'0 sbca #0 staa save1 stab save1+1 inx pshb bsr tstn pulb bcs done aslb rola aslb rola addb save1+1 adca save1 aslb rola bra cbloop inln6 cmpb #'@ cancel beq newlin inx cpx #LINLEN+2 reach end? bne inln2 newlin bsr crlf inln ldx #2 input line from terminal inln5 dex beq newlin inln2 jsr INCH input character stab linbuf-1,x store it cmpb #'_ backspace? beq inln5 inln3 cmpb #CR carriage return bmi inln2 bne inln6 inln4 clr linbuf-1,x clear last char ldx #linbuf bra linefd crlf ldab #CR cr bsr outch2 linefd ldab #LF lf outch2 jmp OUTCH okm fcb CR,LF fcc 'OK' fcb 0 end