10 ;VERSION OF OHIO SCIENTIFIC 6500 ASSEMBLER/EDITOR
   20 ;WITH MODIFICATION TO REDUCE MEMORY USAGE, BUT
   30 ;WITH P-CODE INTERPRETER WRITTEN IN 6502 CODE.
   40 ;
   50 ;UK101 MONITOR SUBROUTINES USED BY ASSEMBLER:
   60 CIN = $FFEB ;GET CHARACTER FROM KEYBOARD
   70 COUT = $FFEE ;PRINT CHARACTER
   80 LOAD = $FFF4 ;SET LOAD FLAG
   90 SAVE = $FFF7 ;SET SAVE FLAG
  100 ;
  110 ;VARIABLES IN ZERO PAGE ;16 BITS
  120 ;UNLESS STATE OTHERWISE
  130 ;"*" INDICATES THAT LABEL UPDATED IN PROG BODY
  140 LABTBL = $0A ;START OF LABEL TABLE
  150 TXTPOS = $10 ;CURRENT POSITION IN TEXT
  160 LINLEN = $12 ;LENGTH OF CURRENT SOURCE LINE
  170 LINENO = $14 ;LINE NUMBER DURING ASSEMBLY
  180 STTEXT = $16 ;START OF TEXT MEMORY
  190 ENDMEM = $18 ;END OF AVAILABLE MEMORY
  200 ENDTXT = $1A ;END OF SOURCE TEXT
  210 ;DRTYPE USED FOR OTHER FUNCTIONS THAN DIRECTIVES
  220 DRTYPE = $1E ;(8 BITS) 0=.END, 1=.BYT, 2=.WOR, 3=
  230 IP = $24 ;INTERPRETIVE POINTER FOR P-CODE
  240 INSLEN = $2A ;PCODE INSTR LEN (8-BIT)
  250 CONST0 = $2C ;PERMANENTLY SET TO ZERO
  260 CNST14 = $38 ;PREMANENTLY SET TO $0014
  270 CNST10 = $3C ;PERMANENTLY SET TO 10
  280 ASMBRK = $3E ;SET TO 1 IF ASM ADDR CHANGES
  290 PASS = $40 ;ASSEMBLY PASS (1 OR 2)
  300 CONST1 = $42 ;PERMANENTLY SET TO 1
  310 ASMADR = $44 ;ASSEMBLY ADDRESS
  320 ASMOPT = $48 ;ASSEMBLY OPTION (0, 1, 2 OR 3)
  330 CONST3 = $4A ;PERMANENTLY SET TO 3
  340 INSTLN = $4C ;NUMBER OF BYTES IN CURRENT INSTRUCT
  350 NOPBYT = $4E ;PERMANENTLY SET TO $EAEA
  360 INSTRN = $50 ;CURRENT INSTRUCTION (3 BYTES)
  370 CNST80 = $58 ;PERMANENTLY SET TO $80
  380 BUFADR = $68 ;START ADDR OF CODE IN A2 BUFFER
  390 NUMVAL = $6A ;NUMERIC VALUE FROM EXPRESSION
  400 LABL40 = $6C ;LABEL IN BASE-40 (4 BYTES)
  410 ASMOFS = $70 ;OFFSET FOR ASSEMBLY TO MEMORY
  420 CNST50 = $72 ;PERMANENTLY SET TO $0050
  430 CONST2 = $74 ;PERMANENTLY SET TO 2
  440 CNST12 = $76 ;PERMANENTLY SET TO 12
  450 CNST7E = $78 ;PERMANENTLY SET TO $007E
  460 CNST6C = $7A ;PERMANENTLY SET TO $006C
  470 LABVAL = $7E ;VALUE OF LABEL
  480 A2BUFF = $B8 ;18 BYTES BUFFER FOR A2 (TO $CF)
  490 A2BLEN = $D1 ;LENGTH OF BUFFER FOR A2
  500 CHKSUM = $D2 ;CHECKSUM FOR A2 OPTION
  510 CNST44 = $D4 ;PERMANENTLY SET TO $0044
  520 NUMERR = $E2 ;NUMBER OF CURRENT ERRORS
  530 TMPLOC = $E6 ;TEMPORARY STORAGE
  540 CONST4 = $EA ;PERMANENTLY SET TO 4
  550 PRFLAG = $F0 ;IF 1, SOURCE LINE WAS PRINTED
  560 CONST5 = $F2 ;PERMANENTLY SET TO 5
  570 CONST6 = $F4 ;PERMANENTLY SET TO 6
  580 ERRMSG = $F6 ;CURRENT ERRORS (4 BYTES)
  590 CALADR = $FA ;ADDRESS OF CALLING INSTR
  600 ;
  610 ;DEFINITIONS OF P-CODE MNEMONICS
  620 NXLN = $00 ;USED BY LINE EDITOR
  630 BMOV = $01 ;XX=LEN, YY=SRC, ZZ=DST
  640 LIN1 = $02 ;USED BY LINE EDITOR
  650 CLAS = $03 ;CLASSIFY CHARACTER
  660 LRAN = $04 ;DECODE LINE NUMBER RANGE
  670 SKIP = $05 ;SKIP SPACES
  680 LVAL = $06 ;LOOK UP LABEL AS LVALUE
  690 LEXP = $07 ;LOOK UP LABEL IN EXPRESSION
  700 OUTP = $08 ;OUTPUT ASSEMBLER INSTRUCTION
  710 EXPR = $09 ;EVALUATE EXPRESSION
  720 RLBL = $0A ;READ LABEL
  730 BRGR = $2B ;BRANCH IF XX>YY
  740 BEQU = $4B ;BRANCH IF XX=YY
  750 BGEQ = $6B ;BRANCH IF XX>=YY
  760 BLES = $8B ;BRANCH IF XX<YY
  770 BNEQ = $AB ;BRANCH IF XX<>YY
  780 BLEQ = $CB ;BRANCH IF XX<=YY
  790 COMP = $0C ;COMPRESS SOURCE CODE
  800 KBLN = $0D ;READ LINE FROM KEYBOARD
  810 RET4 = $0E ;RETURN USING OFFSET IN 4TH BYTE
  820 SET0 = $0F ;SET XX TO 0
  830 DCIN = $10 ;INPUT DECIMAL NUMBER
  840 RETN = $11 ;RETURN FROM P-CODE SUBROUTINE
  850 RET2 = $12 ;RETURN USING OFFSET IN 2ND BYTE
  860 INCR = $13 ;INCREMENT XX
  870 DECR = $14 ;DECREMENT XX
  880 EX65 = $15 ;EXECUTE 6502 CODE
  890 COPY = $16 ;COPY XX TO YY
  900 PHEX = $17 ;PRINT XX AS HEX NUMBER
  910 RERR = $18 ;RECORD ERROR XX
  920 PDEC = $19 ;PRINT DECIMAL NUMBER IN XX
  930 PLIN = $1B ;PRINT LINE POINTED TO BY XX
  940 GERR = $1C ;GET ERROR CODE AND PUT IT IN XX
  950 PERR = $1D ;PRINT PTR TO ERROR PLUS MESSAGE
  960 MSLN = $1E ;PRINT NEW LINE PLUS MESSAGE
  970 PER6 = $1F ;AS FOR PERR BUT INCR $06 FIRST
  980 SUBZ = $20 ;SUBTRACT: ZZ = XX - YY
  990 ADDZ = $21 ;ADD: ZZ = XX + YY
 1000 MOVB = $22 ;MOVE BYTE IN (00) TO (XX)
 1010 DCMP = $23 ;DECOMP LINE AT (10); STORE IN (02)
 1020 MESG = $24 ;PRINT MESSAGE WITHOUT NEW LINE
 1030 RET3 = $25 ;RETURN USING OFFTSET IN 3RD BYTE
 1040 CHK0 = $65 ;CHECK CHAR WITH PTR AT 00/01
 1050 CHK6 = $10 ;CHECK CHAR WITH PTR AT 06/07
 1060 INC0 = $28 ;INCREMENT 00/01
 1070 SET1 = $29 ;SET XX TO 1
 1080 ;
 1090 ;CODES FOR USE WITH CHK0 OPCODE:
 1100 CAP = $80
 1110 DCM = $81
 1120 SPC = $82
 1130 ;
 1140 HIMEM = $1FFF ;TOP OF AVAILABLE MEMORY 
 1150 ;MAIN ENTRY POINT FOR ASSEMBLER
 1160 *=$0240 ;START AT $0240 FOR UK101
 1170 ;INITIALISE STACK POINTER
 1180        LDX #$FF
 1190        TXS 
 1200 ;
 1210 ;SET ALL OF ZERO PAGE TO 00
 1220        INX ;X = 0
 1230        TXA ;A = 0
 1240 INITZP STA $00,X
 1250        INX 
 1260        BNE INITZP
 1270 ;
 1280 ;INITIALISE LOCATIONS IN ZERO PAGE, USING
 1290 ;ADDRESSES STARTING AT ZPADDR AND CONTENTS
 1300 ;STARTING AT ZPCONT
 1310 L1168  LDY ZPADDR,X
 1320        LDA ZPCONT,X
 1330        STA $0000,Y
 1340        INX 
 1350        CPX #ZPCONT-ZPADDR ;LENGTH OF TABLE
 1360        BNE L1168
 1370 ;
 1380 ;MAIN P-CODE INSTRUCTION EXECUTION LOOP
 1390 L1179  LDA ENDTXT ;UPDATE RECORD OF END OF TEXT
 1400        STA ENDIMG
 1410        LDA ENDTXT+1
 1420        STA ENDIMG+1
 1430 ;GET OPCODE - X IS OPCODE ACTUALLY EXECUTED
 1440        LDY #$00
 1450        LDA (IP),Y
 1460        LDX #$1A
 1470        CMP #$E8
 1480        BCS LDADDR
 1490        LDX #$0B
 1500        AND #$1F
 1510        CMP #$0B
 1520        BEQ LDADDR
 1530        LDA (IP),Y
 1540        LDX #$26
 1550        CMP #$72
 1560        BCS LDADDR
 1570        INX 
 1580        CMP #$3A
 1590        BCS LDADDR
 1600        TAX 
 1610 ;
 1620 ;X NOW CONTAINS OPCODE TO EXECUTE, SO
 1630 ;SET TMPLOC/TMPLOC+1 TO OPCODE ROUTINE
 1640 LDADDR LDA ADDRLO,X
 1650        STA TMPLOC
 1660        LDA ADDRHI,X
 1670        PHA 
 1680        AND #%00001111
 1690        CLC 
 1700        ADC #OF6502/256
 1710        STA TMPLOC+1
 1720 ;
 1730 ;PUT LENGTH OF INSTRUCTION INTO INSLEN
 1740        PLA 
 1750        LSR A 
 1760        LSR A
 1770        LSR A
 1780        LSR A 
 1790        STA INSLEN
 1800 ;
 1810 ;GO TO L11B7 IF OPCODE IS ITSELF WRITTEN IN
 1820 ;P-CODE (OPCODES 00,...,0A)
 1830        CPX #$0B
 1840        BCC L11B7
 1850        INY ;Y = 1
 1860        LDA (IP),Y ;A = 2ND BYTE OF INSTRUCTION
 1870        LDX #0 ;X = 0
 1880 ;EXECUTE OPCODE ;A = 2ND BYTE OF INSTRUCTION
 1890 ;X=0, Y=1, C=1, AND Z=1
 1900        JMP (TMPLOC)
 1910 ;
 1920 ;OPCODE IS LESS THAN $0B, SO THE ROUTINE IS 
 1930 ;NOT IN 6502 MACHINE CODE, BUT IN P-CODE.
 1940 L11B7  LDA INSLEN
 1950        PHA ;PUSH LENGTH OF INSTRUCTION
 1960        LDA IP+1 ;AND PUSH RETURN ADDRESS
 1970 ;STORE CALL ADDRESS
 1980        STA CALADR+1
 1990        PHA 
 2000        LDA IP
 2010        STA CALADR
 2020        PHA 
 2030        LDX TMPLOC
 2040        LDA TMPLOC+1
 2050 L11CA  STX IP
 2060        STA IP+1
 2070        BNE L1179 ;ALWAYS BRANCHES - GO BACK TO EXE
 2080 ;
 2090 OF6502=*/256*256
 2100 ;OPCODE $14 XX
 2110 ;DECREMENT 16-BIT VALUE IN XX/XX+1
 2120 L02DC  LDY #$FF
 2130        CLC 
 2140        .BYTE $2C
 2150 ;
 2160 ;OPCODE $13 XX
 2170 ;INCREMENT 16-BIT VALUE IN XX/XX+1
 2180 L02D0  TAX 
 2190 ;
 2200 ;OPCODE $28
 2210 ;INCREMENT 16-BIT VALUE IN 00/01
 2220 L11CE  DEY 
 2230        TYA 
 2240        ADC $00,X
 2250        PHA 
 2260        TYA 
 2270        ADC $01,X
 2280 PULLZP STA $01,X
 2290        PLA 
 2300        STA $00,X
 2310 ;ADD INSTRUCTION LENGTH ONTO INTERPRETIVE POINTER
 2320 ;THEN EXECUTE NEXT INSTRUCTION
 2330 L11CF  LDA INSLEN
 2340        BNE L02AA ;ALWAYS BRANCHES
 2350 ;EXECUTE P-CODE - PULL ADDRESS OFF STACK
 2360 L11DC  PLA 
 2370        STA IP
 2380        PLA 
 2390        STA IP+1
 2400        LDA #$01
 2410        BNE L02AA
 2420 DELCHR TYA 
 2430        BEQ L020C
 2440        LDA #$08
 2450        JSR COUT
 2460        LDA #$20
 2470        JSR COUT
 2480        LDA #$08
 2490        JSR COUT
 2500 ;
 2510 ;OPCODE $0D
 2520 ;INPUT LINE OF TEXT FROM THE KEYBOARD.
 2530 ;START ADDRESS OF LINE IS HELD IN $02/$03,
 2540 ;AND MAXIMUM LENGTH OF LINE IS 56 CHARACTERS
 2550 L0205  DEY 
 2560 ;GET A CHARACTER FROM THE KEYBOARD
 2570 L020C  JSR CIN
 2580        CMP #$1C
 2590        BEQ DELCHR
 2600        STA ($02),Y
 2610        CMP #$0D
 2620        BEQ L0235
 2630        CPY #$37
 2640        BEQ L020C
 2650        CMP #$20
 2660        BMI L020C
 2670        JSR COUT
 2680 L0229  INY 
 2690        BNE L020C
 2700 L0235  JSR COUT
 2710        LDA $02
 2720        STA $00
 2730        BNE JL11CF ;ALWAYS BRANCHES
 2740 ;
 2750 ;OPCODE $27 YY
 2760 ;CHECKS NEXT CHARACTER IN TEXT,
 2770 ;USING POINTER AT $06/$07
 2780 ;THE OPCODE $27 DOES NOT APPEAR IN THE CODE
 2790 ;XX IS THE OPCODE MINUS $10 FOR OPCODE $27,
 2800 ;AND THE OPCODE MINUS $65 FOR OPCODE $26
 2810 ;IF XX < $80 IT CHECKS FOR CHARACTER XX
 2820 ;IF XX = $80 (CAP), CHECKS FOR A CAPITAL LETTER
 2830 ;IF XX = $81 (DEC), CHECKS FOR A DECIMAL DIGIT
 2840 ;IF XX = $82 (SPC), CHECKS FOR CONTROL CHAR OR SP
 2850 ;THE SECOND BYTE, YY, IS THE BRANCH OFFSET
 2860 L0244  LDX #$06 ;X IDENTIFIES TEXT POINTER
 2870 ;$EF IS THE COMPLEMENT OF $10, BUT MINUS
 2880 ;1 BECAUSE THE CARRY FLAG IS ALWAYS SET
 2890        LDA #$EF
 2900        .BYTE $2C
 2910 ;
 2920 ;OPCODE $26 - INSTRUCTION LENGTH = 2
 2930 ;SAME AS OPCODE $27 BUT USES POINTER AT $00/$01
 2940 ;X HAS BEEN SET TO ZERO ANYWAY
 2950 ;SECOND BYTE IS RELATIVE BRANCH OFFSET
 2960 ;THE OPCODE $26 DOES NOT APPEAR IN THE CODE
 2970 ;$9A IS THE COMPLEMENT OF $65, BUT MINUS
 2980 ;1 BECAUSE THE CARRY FLAG IS ALWAYS SET
 2990 L0240  LDA #$9A
 3000        DEY 
 3010        ADC (IP),Y
 3020        BMI L0256
 3030        EOR ($00,X)
 3040        BNE JL11CF ;GO ON TO NEXT INSTRUCTION
 3050 ;BRANCH USING SECOND BYTE OF INSTRUCTION
 3060 L0251  LDY #$01
 3070        BNE L0284 ;ALWAYS BRANCHES
 3080 ;
 3090 ;OPCODES $0E, $25 AND $12 - INSTR LEN = 1
 3100 OP1203 INY ;4TH BYTE OF CALL IS BRANCH OFFSET
 3110 OP1202 INY ;3RD BYTE OF CALL IS BRANCH OFFSET
 3120 OP1201 INX ;2ND BYTE OF CALL IS BRANCH OFFSET
 3130 ;
 3140 ;OPCODE $11 - INSTRUCTION LENGTH = 1 
 3150 ;RETURN FROM P-CODE SUBROUTINE
 3160 L02BC  PLA 
 3170        STA IP
 3180        PLA 
 3190        STA IP+1
 3200        PLA 
 3210        DEX 
 3220        BMI L02AA ;NEXT INSTRUCTION IF NO BRANCH
 3230 ;RELATIVE BRANCH, WHERE Y INDEXES THE SIGNED
 3240 ;8-BIT OFFSET
 3250 L0284  LDA (IP),Y
 3260        TAX 
 3270        CLC 
 3280        ADC IP
 3290        STA IP
 3300        TXA 
 3310        AND #$80 
 3320        BEQ L0295
 3330        LDA #$FF
 3340 L0295  ADC IP+1
 3350        STA IP+1
 3360 ;ADD Y REGISTER ONTO INTERPRETIVE POINTER
 3370 ;THEN CONTINUE WITH P-CODE EXECUTION
 3380 L02A9  TYA 
 3390 L02AA  CLC 
 3400        ADC IP
 3410        STA IP
 3420        BCC L1220
 3430        INC IP+1
 3440 L1220  JMP L1179 ;GO TO EXECUTE NEXT INSTRUCTION 
 3450 ;SEE IF THE NEXT CHARACTER FORM THE SOURCE CODE I
 3460 ;A=$80 = CAPITAL LETTER
 3470 ;A=$81 = DECIMAL DIGIT
 3480 ;A=$82 = CONTROL CHARACTER (LESS THAN $20) OR SPA
 3490 L0256  TAY 
 3500        LDA ($00,X)
 3510        CMP L0267-$80,Y
 3520        BMI JL11CF
 3530        CMP L026B-$80,Y
 3540        BMI L0251
 3550        BPL JL11CF
 3560 L0267  .BYTE $41,$30,$00
 3570 L026B  .BYTE $5B,$3A,$21
 3580 ;
 3590 ;OPCODE $16 XX YY
 3600 ;COPY 16-BIT NUMBER FROM XX/XX+1 TO YY/YY+1
 3610 ;IF MSB OF XX IS SET, IT INDEXES CALLING P-CODE 
 3620 L0270  JSR L04A0 ;GET NEXT ARGUMENT IN LIST
 3630        BCS COPY16 ;ALWAYS BRANCHES
 3640 ;
 3650 ;OPCODES $0F YY AND $29 FF
 3660 ;LOCATIONS CONST0 AND CONST01 ARE PERMANENTLY
 3670 ;TO 0 AND 1 RESPECTIVELY
 3680 CODE0F LDX #CONST0 
 3690        .BYTE $2C 
 3700 CODE29 LDX #CONST1
 3710        TAY ;2ND BYTE OF INSTR TO Y 
 3720 COPY16 LDA $00,X
 3730        STA $0000,Y
 3740        LDA $01,X
 3750        STA $0001,Y
 3760 JL11CF JMP L11CF ;EXECUTE NEXT INSTRUCTION
 3770 ;
 3780 ;OPCODE $1A
 3790 ;P-CODE JUMP INSTRUCTION ;REPRESENTED IN THE CODE
 3800 ;ITSELF AS JUMP ADDRESS MINUS START OF ASSEMBLER 
 3810 ;$E800, IN THE FORMAT OF HIGH BYTE FOLLOWED BY LO
 3820 L029C  TAX 
 3830        DEY 
 3840        LDA (IP),Y
 3850        CMP #$FA
 3860        BCC LITAD
 3870        TAY 
 3880        LDX ADRLO-$FA,Y
 3890        LDA ADRHI-$FA,Y
 3900 SCONST = OFFSET/256-1
 3910 LITAD  SBC #SCONST
 3920 LSTAD  JMP L11CA
 3930 ADRLO  .BYTE L08B7,L0CDC,L0D11
 3940        .BYTE L0620,L08E6,LINOUT
 3950 ADRHI  .BYTE L08B7/256+SCONST
 3960        .BYTE L0CDC/256+SCONST
 3970        .BYTE L0D11/256+SCONST
 3980        .BYTE L0620/256+SCONST
 3990        .BYTE L08E6/256+SCONST
 4000        .BYTE LINOUT/256+SCONST
 4010 ;
 4020 ;OPCODE $15 - INSTRUCTION LENGTH = 1
 4030 ;RETURN TO EXECUTING 6502 MACHINE CODE
 4040 ;X=0, Y=1 AND C=1
 4050 EX6502 INC IP
 4060        BNE L02EA
 4070        INC IP+1
 4080 L02EA  JMP (IP)
 4090 ;
 4100 ;OPCODE $22 XX
 4110 ;MOVE SINGLE BYTE POINTED TO BY 00/01
 4120 ;TO LOCATION POINTED TO BY XX/XX+1
 4130 L04AF  TAX 
 4140        DEY 
 4150        LDA ($00),Y
 4160        STA ($00,X)
 4170 ;ALWAYS BRANCHES - ADVANCE
 4180 ;INTERPRETIVE POINTER AND CONTINUE
 4190        BCS JL11CF
 4200 ;
 4210 ;OPCODE $10 XX BB 
 4220 ;INPUT A 16-BIT DECIMAL NUMBER INTO XX/XX+1
 4230 ;WITH BB BEING A BRANCH OFFSET IN CASE OF OVERFLO
 4240 ;(I.E. RESULT > 65535).  THE TEXT FOR THE NUMBER
 4250 ;ITSELF STARTS AT LOCATION POINTED TO BY $06-$07,
 4260 ;AND $08 CONTAINS THE NUMBER OF DIGITS.  ALL THE
 4270 ;DIGITS HAVE BEEN CONFIRMED TO BE DECIMAL DIGITS
 4280 ;ALREADY.  THE ASSEMBLER ITSELF DOES NOT USE THIS
 4290 ;OPCODE ;IT IS ONLY USED BY THE LINE EDITOR.
 4300 L0300  STX $26
 4310        STX $EC
 4320        TAX 
 4330        LDA #$00
 4340        STA $00,X
 4350        STA $01,X
 4360 L030D  LDY $26
 4370        LDA ($06),Y
 4380        AND #$0F
 4390        STA TMPLOC+1
 4400        TXA 
 4410        TAY 
 4420        LDA #CNST10
 4430        JSR L0A84
 4440        BNE L0327 ;BRANCH IF OVERFLOW
 4450        INC $26
 4460        DEC $08
 4470        BNE L030D
 4480 L3980  BEQ JL11CF ;ADVANCE IP AND EXECUTE
 4490 ;
 4500 ;OPCODE $1C XX BB
 4510 ;REMOVE ERROR NUMBER AND TEXT POINTER FROM STACK 
 4520 ;BRANCH BB IS TAKEN IF STACK IS EMPTY
 4530 L0BC5  TAY 
 4540        STX $01,Y
 4550        LDX NUMERR
 4560        BEQ L0327
 4570        LDA ERRMSG+1,X
 4580        STA $06
 4590        LDA ERRMSG-1,X
 4600        STA $0000,Y
 4610        DEC NUMERR
 4620        BPL JL11CF ;ALWAYS BRANCHES
 4630 ;BRANCH, USING 3RD BYTE OF INSTR
 4640 L0327  LDY #$02
 4650        JMP L0284
 4660 ;PRINT NEW LINE
 4670 NEWLIN LDA #$0D
 4680 L033E  JSR COUT ;PRINT CHARACTER IN ACC
 4690 L0341  LDA #$0A
 4700 ;PRINT CHARACTER IN ACCUMULATOR
 4710 CHROUT JMP COUT 
 4720 ;OPCODE $1F - INSTRUCTION LENGTH VARIABLE
 4730 L03EC  INC $06
 4740        JSR L0341
 4750 ;
 4760 ;OPCODE $1D - INSTRUCTION LENGTH VARIABLE
 4770 ;PRINT POINTER TO ERROR IN LINE OF TEXT, PLUS
 4780 ;ERROR MESSAGE.  START BY PRINTING LINE OF DASHES
 4790 ;UP TO CURRENT POINT IN TEXT.
 4800 L0363  ;CARRY SET BY DEFAULT
 4810        LDA $06
 4820        SBC $02
 4830        BEQ L0373
 4840        TAX 
 4850        LDA #$2D
 4860 L036D  JSR COUT ;PRINT CHARACTER IN ACC
 4870        DEX 
 4880        BNE L036D
 4890 ;PRINT UP-ARROW
 4900 L0373  LDA #$5E
 4910        JSR COUT ;PRINT CHARACTER IN ACC
 4920 ;PRINT CARRIAGE RETURN
 4930        LDA #$0D
 4940        JSR COUT ;PRINT CHARACTER IN ACC
 4950 ;OPCODE $1E - INSTRUCTION LENGTH VARIABLE
 4960 ;PRINT MESSAGE, TERMINATED WITH $00, BUT PRINT
 4970 ;LINE FEED FIRST.
 4980 L037D  JSR L0341
 4990 ;
 5000 ;OPCODE $24 - INSTRUCTION LENGTH VARIABLE
 5010 ;PRINT MESSAGE, TERMINATED WITH #$00 OR #$0D (CR)
 5020 L0380  LDA (IP),Y
 5030        INY 
 5040        TAX ;CHECK FOR END OF MESSAGE
 5050        BEQ L0391
 5060        JSR COUT ;PRINT CHARACTER IN ACC
 5070        CMP #$0D
 5080        BNE L0380
 5090        JSR L0341 
 5100 L0391  JMP L02A9 
 5110 ;
 5120 ;OPCODE $0B - 0B XX YY BB
 5130 ;THIS WORKS FOR OPCODES 0B, 2B, 4B, 6B, 8B, AB,
 5140 ;CB AND EB, ALTHOUGH 0B AND EB NEVER OCCUR. 
 5150 ;COMPARES 16-BIT QUANTITIES IN ZERO PAGE AT
 5160 ;LOCATIONS XX/XX+1 AND .BYTE SET1,/.BYTE SET1,+1,
 5170 ;ON BB IF APPROPRIATE
 5180 ;2B:  BRANCHES IF XX > YY
 5190 ;4B:  BRANCHES IF XX = YY
 5200 ;6B:  BRANCHES IF XX >= YY
 5210 ;8B:  BRANCHES IF XX < YY
 5220 ;AB:  BRANCHES IF XX <> YY
 5230 ;CB:  BRANCHES IF XX <= YY
 5240 L03A0  JSR L04A0
 5250 ;CARRY SET IMPLICITLY 
 5260        LDA $00,X
 5270        SBC $0000,Y
 5280        STA $E5
 5290        LDA $01,X
 5300        SBC $0001,Y
 5310        ORA $E5
 5320        BEQ L03C4
 5330        LDA #%01100000 
 5340        BCS L03C4
 5350        ASL A ;A = $C0
 5360 L03C4  EOR #%01000000 
 5370        LDY #$00
 5380        AND (IP),Y
 5390 L4820  BEQ L3980 ;EXECUTE NEXT INSTRUCTION
 5400 L03CE  LDY #$03
 5410        JMP L0284 ;EXECUTE RELATIVE BRANCH
 5420 ;
 5430 ;OPCODE $20 - 20 XX YY ZZ
 5440 ;SUBTRACT 16-BIT QUANTITY IN YY FROM XX
 5450 ;AND PUT RESULT IN ZZ 
 5460 L0419  DEX ;FLAG = $FF TO SUBTRACT
 5470        .BYTE $24 ;KEEP CARRY SET
 5480 ;
 5490 ;OPCODE $21 - 21 XX YY ZZ
 5500 ;ADD TOGETHER 16-BIT QUANTITIES AT XX AND .BYTE S
 5510 ;PUT RESULT IN ZZ
 5520 L0400  CLC 
 5530        STX $E4
 5540        JSR L04A0
 5550        LDA $0000,Y
 5560        EOR $E4
 5570        ADC $00,X
 5580        PHA 
 5590        LDA $0001,Y
 5600        EOR $E4
 5610        ADC $01,X
 5620        PHA 
 5630        LDY #$03
 5640        LDA (IP),Y
 5650        TAX 
 5660        PLA 
 5670        JMP PULLZP
 5680 ;
 5690 ;OPCODE $0C - INSTRUCTION LENGTH = 1 
 5700 ;COMPRESS LINE OF ASSEMBLER SOURCE CODE
 5710 L0440  STX $28
 5720        STX $0E
 5730        STX $27
 5740 L0446  STX $26
 5750 L0448  LDY $28
 5760        LDA ($00),Y
 5770        CMP $27
 5780        BNE L0456
 5790        DEC $26
 5800        INC $28
 5810        BNE L0448
 5820 L0456  TAX 
 5830        LDY $0E
 5840        LDA $26
 5850        BEQ L0460
 5860        STA ($00),Y
 5870        INY 
 5880 L0460  TXA 
 5890        STA ($00),Y
 5900        STA $27
 5910        INC $28
 5920        INY 
 5930        STY $0E
 5940        LDX #$00
 5950        CMP #$0D
 5960        BNE L0446
 5970        STX $0F
 5980        BEQ L4820 ;ALWAYS BRANCHES
 5990 ;
 6000 ;CALLED BY BLOCK MOVE SUBROUTINE
 6010 ;RETURN WITH Z FLAG SET IF TRANSFERRED
 6020 ;LAST BYTE OF BLOCK
 6030 L03F2  LDA ($26),Y
 6040        STA ($28),Y
 6050        INC $FE
 6060        BNE L03F6
 6070        INC $FF
 6080 L03F6  RTS 
 6090 ;
 6100 ;**************************************
 6110 ;THE FOLLOWING DECLARATIONS PRECEDE THE
 6120 ;FIRST PIECE OF PSEUDOCODE
 6130 ;**************************************
 6140 OFS=*/256*256
 6150 OFFSET = $E800-OFS
 6160 ;
 6170 ;OPCODE $00 - INSTRUCTION LENGTH = 2
 6180 ;STEP ON TO NEXT LINE OF SOURCE FILE -
 6190 ;PUT LOCATION IN TXTPOS, AND
 6200 ;PUT LENGTH IN LINLEN
 6210 ;PUT LINE NUMBER IN $38
 6220 ;TAKE RELATIVE BRANCH IN 2ND BYTE IF END
 6230 L047C  .BYTE ADDZ,TXTPOS,LINLEN,TXTPOS
 6240        .BYTE ADDZ,LINENO,CONST1,LINENO
 6250        .BYTE SET0,LINLEN
 6260        .BYTE BNEQ,TXTPOS,ENDTXT,L048E-*
 6270        .BYTE RET2 ;RETURN - 2ND BYTE OF CALL IS BR
 6280 ;
 6290 ;OPCODE $02 - INSTRUCTION LENGTH = 1 
 6300 ;FETCH FIRST LINE OF SOURCE FILE -
 6310 ;PUT LOCATION IN TXTPOS, AND
 6320 ;PUT LENGTH IN LINLEN
 6330 ;PUT LINE NUMBER IN $38
 6340 L03D4  .BYTE COPY,STTEXT,TXTPOS
 6350        .BYTE BEQU,TXTPOS,ENDTXT,L04E6-* ;RET
 6360 L048E  .BYTE BMOV,CONST2,TXTPOS,$38
 6370 ;AND PUT LENGTH OF LINE IN LINLEN
 6380        .BYTE EX65
 6390 ;SKIP OVER 2 BYTES LINE NUMBER
 6400 L0493  INY 
 6410        LDA (TXTPOS),Y
 6420        CMP #$0D
 6430        BNE L0493
 6440        INY 
 6450        STY LINLEN
 6460        JMP L02BC ;RETURN FROM P-CODE SUBROUTINE
 6470 ;GET NEXT ARGUMENT IN LIST.
 6480 ;LOOK AT NEXT ARGUMENT FOR P-CODE INSTRUCTION.
 6490 ;IF THAT ARGUMENT IS NEGATIVE, USE IT TO INDEX
 6500 ;CALLING INSTRUCTION.
 6510 L04A0  LDA (IP),Y
 6520        BPL L04AD
 6530        AND #$7F
 6540        TAY 
 6550        LDA (CALADR),Y
 6560 L04AD  TAX 
 6570        LDY #$02
 6580        LDA (IP),Y
 6590        TAY 
 6600        RTS 
 6610 ;
 6620 ;OPCODE $01 XX YY, ZZ - MEMORY BLOCK MOVE
 6630 ;XX IS LENGTH OF BLOCK (IN $46/$47)
 6640 ;YY IS START OF SOURCE (IN $26/$27)
 6650 ;ZZ IS START OF DESTINATION (IN $28/$29)
 6660 L04C0  .BYTE COPY,$81,$46 ;STORE LENGTH
 6670 ;EXIT IF LENGTH IS ZERO
 6680        .BYTE BEQU,$46,CONST0,L04E6-* 
 6690        .BYTE SUBZ,CONST0,$46,$FE
 6700        .BYTE COPY,$82,$26 ;STORE SOURCE
 6710        .BYTE COPY,$83,$28 ;STORE DESTINATION
 6720 ;BRANCH IF DESTINATION HIGHER THAN SOURCE
 6730        .BYTE BLES,$26,$28,L04E7-* 
 6740 ;SOURCE ADDRESS HIGHER THAN DEST ADDRESS
 6750 ;START BLOCK MOVE FROM LOWEST ADDRESS
 6760        .BYTE EX65
 6770        DEY 
 6780        BEQ L04DE ;ALWAYS BRANCHES
 6790 L04D7  INY 
 6800        BNE L04DE
 6810        INC $27
 6820        INC $29
 6830 L04DE  JSR L03F2
 6840        BNE L04D7
 6850 L04E3  JSR L11DC ;EXECUTE P-CODE
 6860 L04E6  .BYTE RETN
 6870 ;DEST ADDRESS HIGHER THAN SOURCE ADDRESS
 6880 ;START BLOCK MOVE FROM HIGHEST ADDRESS
 6890 L04E7  .BYTE EX65
 6900        CLC 
 6910        LDA $47
 6920        ADC $27
 6930        STA $27
 6940        LDA $47
 6950        ADC $29
 6960        STA $29
 6970        LDY $46
 6980 L04F1  TYA 
 6990        BNE L04F8
 7000        DEC $27
 7010        DEC $29
 7020 L04F8  DEY 
 7030        JSR L03F2
 7040        BNE L04F1
 7050        BEQ L04E3
 7060 ;
 7070 ;OPCODE $1B - INSTRUCTION LENGTH = 2
 7080 ;PRINT LINE POINTED TO BY LOCATION XX/XX+1
 7090 ;CARRIES OUT DECOMPRESSION OF TEXT
 7100 L0500  TAX 
 7110        LDA $00,X
 7120        STA $26
 7130        LDA $01,X
 7140        STA $27
 7150        DEY 
 7160 L050C  LDX #$FF
 7170        LDA ($26),Y
 7180        BPL L0515
 7190        TAX 
 7200        LDA $28
 7210 L0515  JSR COUT ;PRINT CHARACTER IN ACC
 7220        INX 
 7230        BMI L0515
 7240        STA $28
 7250        INY 
 7260        CMP #$0D
 7270        BNE L050C
 7280        LDA #$00
 7290        JSR L033E
 7300 L6610  JMP L11CF ;ADVANCE INTERPRETIVE POINTER AND
 7310 ;OPCODE 19 XX
 7320 ;PRINT DIGIT DECIMAL NUMBER IN LOCATIONS XX
 7330 ;AND XX+1, RIGHT-JUSTIFIED IN A FIELD OF 5
 7340 ;CHARACTERS
 7350 L0590  TAX 
 7360        LDA $00,X
 7370        STA $26
 7380        LDA $01,X
 7390        STA $27
 7400        LDA #$05
 7410        STA $46
 7420        LDX #$26
 7430        LDY #CNST10
 7440        LDA #$28
 7450 L05A5  JSR L052A
 7460        STA $47
 7470        LDA $00,X
 7480        PHA 
 7490        TXA 
 7500        LDX $47
 7510        DEC $46
 7520        BNE L05A5
 7530        LDX #$80
 7540 L05B6  PLA 
 7550        BEQ L05BE
 7560        TAX 
 7570        ORA #$30
 7580        BNE L05C5
 7590 L05BE  ORA #$30
 7600        INX 
 7610        BPL L05C5
 7620        LDA #$20
 7630 L05C5  JSR COUT ;PRINT CHARACTER IN ACC
 7640        INC $46
 7650        LDA $46
 7660        CMP #$05
 7670        BNE L05B6
 7680        BEQ L6610 ;ADVANCE INTERPRETIVE POINTER AND
 7690 ;DIVISION SUBROUTINE:
 7700 ;(A) = (X) / (Y)
 7710 L052A  STA $E4
 7720        STX $E5
 7730        STY TMPLOC
 7740        LDX TMPLOC
 7750        LDY #$01
 7760        LDA $01
 7770        BMI L0543
 7780 L0538  INY 
 7790        ASL $00,X
 7800        ROL $01,X
 7810        BMI L0543
 7820        CPY #$11
 7830        BNE L0538
 7840 L0543  STY TMPLOC+1
 7850        LDY $E4
 7860        LDX #$00
 7870        STX $00,Y
 7880        STX $01,Y
 7890        LDY TMPLOC
 7900 L054F  LDX $E5
 7910        SEC 
 7920        LDA $00,X
 7930        SBC $0000,Y
 7940        STA $EC
 7950        LDA $01,X
 7960        SBC $0001,Y
 7970        BCC L0566
 7980        STA $01,X
 7990        LDA $EC
 8000        STA $00,X
 8010 L0566  LDX $E4
 8020        ROL $00,X
 8030        ROL $01,X
 8040        DEC TMPLOC+1
 8050        BEQ L0583
 8060        LDX TMPLOC
 8070        LSR $01,X
 8080        ROR $00,X
 8090        SEC 
 8100        BCS L054F
 8110 L0583  LDA $E4
 8120        LDX $E5
 8130        RTS 
 8140 ;'R' COMMAND
 8150 L066C  .BYTE COPY,CNST10,$36
 8160        .BYTE LIN1
 8170 L0831  .BYTE BEQU,TXTPOS,ENDTXT,L0842-*
 8180        .BYTE BMOV,CONST2,$3A,TXTPOS
 8190        .BYTE ADDZ,CNST10,$36,$36
 8200        .BYTE NXLN,L0842-*
 8210        .DBYTE L0831+OFFSET
 8220 L0842  .BYTE MSLN,$00
 8230        .BYTE LIN1
 8240        .BYTE PDEC,$36
 8250        .DBYTE PSTART+OFFSET
 8260 ;LINE NUMBER FOUND
 8270 L0663  .DBYTE L0690+OFFSET
 8280 ;'P' COMMAND
 8290 L0666  .DBYTE L0750+OFFSET
 8300 ;'D' COMMAND
 8310 L0669  .DBYTE L07D0+OFFSET
 8320 ;***********************************
 8330 ;ENTRY POINT FOR P-CODE UPON STARTUP
 8340 PINIT  .BYTE COPY,STTEXT,TXTPOS
 8350 PSTART .BYTE MESG,$0D ;PRINT NEW LINE
 8360 ;************************************
 8370 L0601  .BYTE CLAS,L0663-*,L0605-*,L0620-* 
 8380 L0605  .BYTE CHK6+'A,L0660-* ;TEST FOR 'A' COMMAN
 8390        .BYTE CHK6+'P,L0666-* ;TEST FOR 'P' COMMAN
 8400        .BYTE CHK6+'I,LICMD-* ;TEST FOR 'I' COMMAN
 8410        .BYTE CHK6+'D,L0669-* ;TEST FOR 'D' COMMAN
 8420        .BYTE CHK6+'R,L066C-* ;TEST FOR 'R' COMMAN
 8430 L0614  .BYTE CHK6+'S,L130C-* ;'S' COMMAND
 8440        .BYTE CHK6+'L,L1316-* ;'L' COMMAND
 8450 CMDERR .BYTE PER6,'CMD ERR',$0D 
 8460 L0620  .BYTE MSLN,'.',$00 ;PRINT FULL STOP
 8470        .BYTE KBLN ;GET LINE OF KEYBOARD INPUT 
 8480        .DBYTE L0601+OFFSET
 8490 ;
 8500 ;'S' AND 'L' COMMANDS FOR UK101 VERSION
 8510 ;'S' COMMAND
 8520 L130C  .BYTE EX65 ;EXECUTE 6502 MACHINE CODE
 8530        JSR SAVE ;TURN ON SAVE FLAG
 8540        JMP L1310
 8550 ;'L' COMMAND
 8560 L1316  .BYTE EX65 ;EXECUTE 6502 MACHINE CODE
 8570        JSR LOAD
 8580 L1310  JSR L11DC ;RETURN TO P-CODE
 8590        .BYTE $FD ;JMP TO L0620
 8600 ;'A' COMMAND
 8610 L0660  .BYTE MSLN,$0D
 8620        .BYTE BEQU,STTEXT,ENDTXT,L0620-*
 8630        .BYTE SET1,ASMBRK
 8640        .BYTE SET0,ASMOPT
 8650        .BYTE SET0,A2BLEN-1 ;SET NO. BYTES FOR A2 T
 8660        .BYTE CLAS,L112A-*,CMDERR-*,L112D-*
 8670        .DBYTE CMDERR+OFFSET
 8680 L112A  .BYTE DCIN,ASMOPT,CMDERR-*
 8690 L112D  .DBYTE L0850+OFFSET
 8700 ;
 8710 ;OPCODE $03 XX YY ZZ
 8720 ;XX IS RELATIVE BRANCH FOR DECIMAL NUMBER
 8730 ;YY IS RELATIVE BRANCH FOR NOT DECIMAL
 8740 ;NUMBER, NOT CAPITAL LETTER, AND NOT
 8750 ;END OF LINE
 8760 ;ZZ IS RELATIVE BRANCH FOR END OF LINE
 8770 ;NO BRANCH TAKEN IF CAPITAL LETTER
 8780 L0626  .BYTE COPY,$00,$04 ;COPY POINTER
 8790        .BYTE DECR,$00 ;DECREMENT POINTER AT $00/$0
 8800 L062B  .BYTE INC0 ;INC POINTER AT $00/$01
 8810        .BYTE CHK0+$20,L062B-* ;SKIP SPACES
 8820        .BYTE SET0,$08 ;SET CHAR CHOUNT TO ZERO 
 8830        .BYTE COPY,$00,$06 ;COPY POINTER TO $06/$07
 8840        .BYTE CHK0+CAP,L0649-* ;BRANCH IF CAPITAL
 8850        .BYTE CHK0+DCM,L0651-* ;BRANCH IF DECIMAL
 8860        .BYTE CHK0+$0D,L065A-* ;BRANCH IF END OF L
 8870        .BYTE COPY,$00,$06 ;COPY POINTER TO $06/$07
 8880 ;THE FOLLOWING LINE IS ALMOST CERTAINLY ANOMOLOUS
 8890 ;SO IT HAS BEEN COMMENTED OUT. 
 8900 ;.BYTE COPY,PRFLAG,$08 ;COPY FROM $F0/$F1 TO $08/$
 8910        .BYTE INC0 ;INCREMENT POINTER AT $00/$01
 8920        .BYTE RET3 ;RETURN - 3RD BYTE OF CALL IS OF
 8930 ;CAPITAL LETTER FOUND
 8940 L0649  .BYTE INC0
 8950        .BYTE INCR,$08
 8960        .BYTE CHK0+CAP,L0649-*
 8970        .BYTE RETN
 8980 ;DECIMAL DIGIT FOUND
 8990 L0651  .BYTE INC0
 9000        .BYTE INCR,$08
 9010        .BYTE CHK0+DCM,L0651-*
 9020        .BYTE RET2 ;2ND BYTE OF CALL IS OFFSET
 9030 ;END OF LINE FOUND
 9040 L065A  .BYTE RET4 ;4TH BYTE OF CALL IS OFFSET
 9050 ;'I' COMMAND
 9060 LICMD  .BYTE MSLN,'INIZ?',$00
 9070        .BYTE KBLN ;GET LINE OF KEYBOARD INPUT
 9080        .BYTE COPY,STTEXT,$10
 9090        .BYTE SET0,LINLEN
 9100        .BYTE CHK0+'Y,L068A-*
 9110        .BYTE $FD ;JMP TO L0620
 9120 L068A  .BYTE COPY,STTEXT,ENDTXT
 9130        .BYTE $FD ;JMP TO L0620
 9140 ;****************************
 9150 ;LINE NUMBER FOUND ON COMMAND LINE.
 9160 ;INPUT DECIMAL NUMBER TO $36/$37.
 9170 ;GO TO L06F3 IF TOO BIG.
 9180 L0690  .BYTE DCIN,$36,L06F3-* 
 9190        .BYTE COMP ;COMPRESS REST OF LINE
 9200        .BYTE ADDZ,$0E,CONST2,$0E
 9210        .BYTE BEQU,$36,CONST0,L06B1-*
 9220        .BYTE BGEQ,$36,LINENO,L06A3-*
 9230        .BYTE LIN1
 9240 L06A3  .BYTE BGEQ,LINENO,$36,L06AC-*
 9250        .BYTE NXLN,L06B1-*
 9260        .DBYTE L06A3+OFFSET
 9270 L06AC  .BYTE BEQU,LINENO,$36,L06B4-*
 9280 L06B1  .BYTE SET0,LINLEN
 9290 L06B4  .BYTE ADDZ,TXTPOS,$0E,$1C
 9300        .BYTE ADDZ,TXTPOS,LINLEN,DRTYPE
 9310        .BYTE SUBZ,ENDTXT,DRTYPE,$20
 9320        .BYTE ADDZ,$1C,$20,$22
 9330        .BYTE BRGR,$22,ENDMEM,L06EA-*
 9340        .BYTE BMOV,$20,DRTYPE,$1C
 9350        .BYTE SUBZ,$0E,CONST2,$1C
 9360        .BYTE ADDZ,TXTPOS,CONST2,DRTYPE
 9370        .BYTE BMOV,$1C,$00,DRTYPE
 9380        .BYTE BEQU,$36,CONST0,L05DB-*
 9390        .BYTE COPY,$36,LINENO
 9400 L05DB  .BYTE BMOV,CONST2,$3A,TXTPOS
 9410        .BYTE COPY,$0E,LINLEN
 9420        .BYTE COPY,$22,ENDTXT
 9430        .BYTE NXLN,L06E8-*
 9440 L06E8  .BYTE $FD ;JMP TO L0620
 9450 L06EA  .BYTE MSLN,'*FULL',$0D
 9460        .BYTE $FD ;JMP TO L0620
 9470 L06F3  .BYTE PER6,'#TOO BIG',$0D
 9480        .BYTE $FD ;JMP TO L0620
 9490 ;
 9500 ;OPCODE $04 - INSTRUCTION LENGTH = 2
 9510 ;SECOND BYTE IS AN OFFSET
 9520 L0700  .BYTE SET0,$1C
 9530        .BYTE COPY,$2E,DRTYPE
 9540        .BYTE CLAS,L070C-*,L071C-*,L074E-* 
 9550        .BYTE COPY,$04,$00
 9560        .BYTE RET2 ;2ND BYTE OF CALL IS BRANCH
 9570 L070C  .BYTE DCIN,$1C,L0741-*
 9580        .BYTE CLAS,L073B-*,L0721-*,L0718-* 
 9590        .BYTE COPY,$1C,DRTYPE ;COPY $1C/$1D INTO D
 9600 L0716  .BYTE COPY,$04,$00
 9610 L0717  .BYTE RETN
 9620 L0718  .BYTE COPY,$1C,DRTYPE
 9630        .BYTE RETN
 9640 L071C  .BYTE CHK6+'-,L0729-*
 9650        .DBYTE L073B+OFFSET
 9660 L0721  .BYTE CHK6+'-,L0729-* ;GO TO L0729 IF DAS
 9670        .BYTE CHK6+',,L0718-* ;GO TO L0718 IF COM
 9680        .DBYTE L073B+OFFSET
 9690 L0729  .BYTE CLAS,L072F-*,L0738-*,L0717-*
 9700        .DBYTE L0716+OFFSET
 9710 L072F  .BYTE DCIN,DRTYPE,L0741-* ;READ DECIMAL N
 9720        .BYTE CLAS,L073B-*,L0738-*,L0717-*
 9730        .DBYTE L0716+OFFSET
 9740 L0738  .BYTE CHK6+',,L0717-*
 9750 L073B  .BYTE PER6,'??',$0D
 9760        .BYTE RET2
 9770 L0741  .BYTE PER6,'#TOO BIG',$0D
 9780 L074E  .BYTE RET2 ;2ND BYTE OF CALL IS BRANCH
 9790 ;'P' COMMAND
 9800 L0750  .BYTE LRAN,L0752-*
 9810 L0752  .BYTE MSLN,$0D
 9820 L0754  .BYTE LIN1
 9830        .BYTE BEQU,TXTPOS,ENDTXT,L0778-*
 9840 L075A  .BYTE BGEQ,LINENO,$1C,L0763-*
 9850        .BYTE NXLN,L0768-*
 9860        .DBYTE L075A+OFFSET
 9870 L0763  .BYTE BLEQ,LINENO,DRTYPE,L076C-*
 9880 L0768  .BYTE LRAN,L0778-*
 9890        .DBYTE L0754+OFFSET
 9900 L076C  .BYTE PDEC,LINENO
 9910        .BYTE ADDZ,TXTPOS,CONST2,$20
 9920        .BYTE PLIN,$20 
 9930        .BYTE NXLN,L0768-*
 9940        .DBYTE L0763+OFFSET
 9950 LEN1=$1000-OF6502
 9960 LEN2=$2000-OF6502
 9970 LEN3=$3000-OF6502
 9980 LEN4=$4000-OF6502
 9990 LENF=$F000-OF6502
10000 OP00=L047C+LEN2
10010 OP01=L04C0+LEN4
10020 OP02=L03D4+LEN1
10030 OP03=L0626+LEN4
10040 OP04=L0700+LEN2
10050 OP05=L0961+LEN1
10060 OP06=L0989+LEN4
10070 OP07=L0985+LEN4
10080 OP08=L10B3+LEN1
10090 OP09=L0C30+LEN2
10100 OP0A=L0AF0+LEN2
10110 OP0B=L03A0+LEN4
10120 OP0C=L0440+LEN1
10130 OP0D=L0205+LEN1
10140 OP0E=OP1203+LEN1
10150 OP0F=CODE0F+LEN2
10160 OP10=L0300+LEN3
10170 OP11=L02BC+LEN1
10180 OP12=OP1201+LEN1
10190 OP13=L02D0+LEN2
10200 OP14=L02DC+LEN2
10210 OP15=EX6502+LEN1
10220 OP16=L0270+LEN3
10230 OP17=L0BE5+LEN2
10240 OP18=L0965+LEN2
10250 OP19=L0590+LEN2
10260 OP1A=L029C+LEN3
10270 OP1B=L0500+LEN2
10280 OP1C=L0BC5+LEN3
10290 OP1D=L0363+LENF
10300 OP1E=L037D+LENF
10310 OP1F=L03EC+LENF
10320 OP20=L0419+LEN4
10330 OP21=L0400+LEN4
10340 OP22=L04AF+LEN2
10350 OP23=L0A60+LEN1
10360 OP24=L0380+LENF
10370 OP25=OP1202+LEN1
10380 OP26=L0240+LEN2
10390 OP27=L0244+LEN2
10400 OP28=L11CE+LEN1
10410 OP29=CODE29+LEN2
10420 ;ADDRESSES FOR OPCODE ROUTINES
10430 ;OPCODES ALLOWED ARE 00 TO 27 INCLUSIVE
10440 ;MSB MAY BE SET, INDICATING P-CODE SUBROUTINE
10450 ADDRLO .BYTE OP00,OP01,OP02,OP03
10460        .BYTE OP04,OP05,OP06,OP07
10470        .BYTE OP08,OP09,OP0A,OP0B
10480        .BYTE OP0C,OP0D,OP0E,OP0F
10490        .BYTE OP10,OP11,OP12,OP13
10500        .BYTE OP14,OP15,OP16,OP17
10510        .BYTE OP18,OP19,OP1A,OP1B
10520        .BYTE OP1C,OP1D,OP1E,OP1F
10530        .BYTE OP20,OP21,OP22,OP23
10540        .BYTE OP24,OP25,OP26,OP27
10550        .BYTE OP28,OP29
10560 ADDRHI .BYTE OP00/256,OP01/256
10570        .BYTE OP02/256,OP03/256
10580        .BYTE OP04/256,OP05/256
10590        .BYTE OP06/256,OP07/256
10600        .BYTE OP08/256,OP09/256
10610        .BYTE OP0A/256,OP0B/256
10620        .BYTE OP0C/256,OP0D/256
10630        .BYTE OP0E/256,OP0F/256
10640        .BYTE OP10/256,OP11/256
10650        .BYTE OP12/256,OP13/256
10660        .BYTE OP14/256,OP15/256
10670        .BYTE OP16/256,OP17/256
10680        .BYTE OP18/256,OP19/256
10690        .BYTE OP1A/256,OP1B/256
10700        .BYTE OP1C/256,OP1D/256
10710        .BYTE OP1E/256,OP1F/256
10720        .BYTE OP20/256,OP21/256
10730        .BYTE OP22/256,OP23/256
10740        .BYTE OP24/256,OP25/256
10750        .BYTE OP26/256,OP27/256
10760        .BYTE OP28/256,OP29/256
10770 L0778  .DBYTE L0601+OFFSET
10780 L07D0  .BYTE LRAN,L0807-*
10790 L07D2  .BYTE SET0,$22
10800        .BYTE LIN1
10810 L07DB  .BYTE BGEQ,LINENO,$1C,L07E4-*
10820        .BYTE NXLN,L0811-*
10830        .DBYTE L07DB+OFFSET
10840 L07E4  .BYTE COPY,TXTPOS,$1C
10850 L07E7  .BYTE BRGR,LINENO,DRTYPE,L07F0-*
10860        .BYTE INCR,$22
10870        .BYTE ADDZ,TXTPOS,LINLEN,$20
10880        .BYTE NXLN,L07F0-*
10890        .DBYTE L07E7+OFFSET
10900 L07F0  .BYTE SUBZ,ENDTXT,$20,DRTYPE
10910        .BYTE BEQU,$22,CONST0,L0811-*
10920        .BYTE BMOV,DRTYPE,$20,$1C
10930        .BYTE ADDZ,$1C,DRTYPE,ENDTXT
10940        .BYTE LIN1
10950        .BYTE LRAN,L0778-*
10960        .DBYTE L07D2+OFFSET
10970 L0807  .BYTE PER6,'LINES?',$0D
10980        .DBYTE L0822+OFFSET
10990 L0811  .BYTE PER6,'NO SUCH LINE(S)',$0D
11000 L0822  .BYTE $FD ;JMP TO L0620
11010 L084A  .BYTE INC0
11020        .BYTE RLBL,L1153-*
11030 ;ERROR 26 - ILLEGAL DIRECTIVE
11040 L114F  .BYTE RERR,$1A
11050        .DBYTE L10A7+OFFSET
11060 L1153  .DBYTE L104E+OFFSET
11070 L084D  .BYTE SET0,INSTLN
11080        .BYTE INC0
11090        .BYTE SKIP ;SKIP SPACES
11100        .BYTE CHK0+'=,L100C-*
11110        .BYTE $FA ;JMP TO L08B7
11120 L100C  .BYTE INC0
11130        .BYTE SKIP ;SKIP SPACES
11140        .BYTE EXPR,L1023-*
11150        .BYTE CHK0+SPC,L1017-*
11160        .BYTE $FE ;JMP TO L08E6
11170 L1017  .BYTE EX65
11180        LDA #$3F 
11190        BIT $ED
11200        BEQ L1025
11210        JSR L11DC ;EXECUTE P-CODE
11220 ;ERROR 4 - FWD REF IN EQUATE DIRECTIVE
11230        .BYTE RERR,$84
11240 L1023  .BYTE $FF ;JMP TO LINOUT
11250 L1025  JSR L11DC ;EXECUTE P-CODE
11260        .BYTE SET1,ASMBRK
11270        .BYTE COPY,NUMVAL,ASMADR
11280        .BYTE $FF ;JMP TO LINOUT
11290 ;
11300 ;'A' COMMAND - ASMOPT HAS ALREADY BEEN
11310 ;SET UP.
11320 L0850  .BYTE SET0,$7C
11330        .BYTE COPY,ENDMEM,LABTBL ;CLEAR LABEL TABL
11340        .BYTE SET1,PASS
11350 ;START NEXT PASS OF ASSEMBLY
11360 NXTPAS .BYTE SET0,ASMADR
11370        .BYTE LIN1 ;GET FIRST LINE OF SOURCE CODE
11380 L085D  .BYTE SET0,PRFLAG ;LINE NOT YET PRINTED
11390        .BYTE SET0,NUMERR ;NO ERRORS SO FAR
11400        .BYTE DCMP ;DECOMPRESS TEXT AT TXTPOS/TXTP
11410        .BYTE COPY,$02,$00 ;MOVE POINTER FOR LINE 
11420 ;SET DEFAULT INSTRUCTION TO 3 NOP BYTES
11430        .BYTE COPY,CONST3,INSTLN
11440        .BYTE COPY,NOPBYT,INSTRN
11450        .BYTE COPY,NOPBYT,INSTRN+2
11460        .BYTE SET0,$54
11470        .BYTE SKIP ;SKIP SPACES
11480        .BYTE CHK0+$0D,L08C6-*
11490        .BYTE CHK0+';,L08AD-*
11500        .BYTE CHK0+'*,L084D-*
11510        .BYTE CHK0+'.,L084A-* ;PROCESS DIRECTIVE
11520        .BYTE RLBL,L0887-*
11530 ;ERROR 9 - LABEL DOESN'T BEGIN WITH LETTER
11540        .BYTE RERR,$09
11550        .BYTE $FF ;JMP TO LINOUT
11560 L0887  .BYTE LVAL,L08AB-*,L08BB-*,L088C-*
11570 L088C  .BYTE SET1,$54
11580        .BYTE CHK0+$20,L0894-*
11590        .DBYTE L089A+OFFSET
11600 L0894  .BYTE SKIP ;SKIP SPACES
11610        .BYTE RLBL,L08B2-*
11620        .BYTE CHK0+'.,L084A-*
11630 L089A  .BYTE CHK0+'*,L084D-*
11640        .BYTE CHK0+'=,L08A8-*
11650        .BYTE CHK0+';,L08AD-*
11660        .BYTE CHK0+$0D,L08AD-*
11670        .BYTE $FA ;JMP TO L08B7
11680 L08A8  .DBYTE L1028+OFFSET
11690 ;ERROR 1 - 'A' IS A RESERVED NAME
11700 L08AB  .BYTE RERR,$01
11710 L08AD  .BYTE SET0,INSTLN
11720        .BYTE $FF ;JMP TO LINOUT
11730 L08B2  .BYTE LEXP,L08B7-*,L08BB-*,L08B7-*
11740 ;ERROR 6 - ILLEGAL OR MISSING OPCODE
11750 L08B7  .BYTE RERR,$06
11760        .BYTE $FF ;JMP TO LINOUT
11770 L08BB  .BYTE CHK0+SPC,L08C0-*
11780        .BYTE $FA ;JMP TO L08B7
11790 L0EBC  .BYTE SET1,INSTLN
11800        .BYTE COPY,$20,INSTRN
11810        .BYTE $FF ;JMP TO LINOUT
11820 L08C0  .BYTE BEQU,DRTYPE,CONST0,L0EBC-*
11830        .BYTE SKIP ;SKIP SPACES
11840 L08C6  .BYTE CHK0+$0D,L090C-*
11850        .BYTE CHK0+'#,IMMADR-*
11860        .BYTE CHK0+'(,INDADR-*
11870        .BYTE COPY,CNST80,$56
11880        .BYTE CHK0+'A,L0950-*
11890 L08D5  .BYTE EXPR,L08F4-*
11900        .BYTE CHK0+',,L0934-*
11910        .BYTE COPY,$5A,$56
11920        .DBYTE L0948+OFFSET
11930 ;
11940 ;PROCESS IMMEDIATE ADDRESSING
11950 IMMADR .BYTE INC0
11960        .BYTE EXPR,L08F4-* ;GET EXPRESSION
11970        .BYTE CHK0+SPC,L08EA-*
11980 ;ERROR 7 - INVALID EXPRESSION
11990 L08E6  .BYTE RERR,$07
12000        .BYTE $FF ;JMP TO LINOUT
12010 L08EA  .BYTE COPY,$5C,$56
12020        .BYTE DECR,INSTLN ;INSTR LEN = 2
12030        .DBYTE L0D3D+OFFSET
12040 L08F4  .BYTE $FF ;JMP TO LINOUT
12050 INDADR .BYTE INC0
12060        .BYTE EXPR,L08F4-*
12070        .BYTE CHK0+',,L0902-*
12080        .BYTE CHK0+'),L0920-*
12090        .BYTE $FE ;JMP TO L08E6
12100 L0902  .BYTE INC0
12110        .BYTE CHK0+'X,L0909-*
12120        .BYTE $FE ;JMP TO L08E6
12130 L0909  .BYTE COPY,$5E,$56
12140        .BYTE INC0
12150        .BYTE CHK0+'),L0910-* 
12160        .BYTE $FE ;JMP TO L08E6
12170 ;ERROR 15 - RAN OFF END OF LINE
12180 L090C  .BYTE RERR,$0F
12190        .BYTE $FF ;JMP TO LINOUT
12200 L0910  .BYTE INC0
12210        .BYTE CHK0+SPC,L0917-*
12220        .BYTE $FE ;JMP TO L08E6
12230 L0917  .BYTE BLES,NUMVAL,CONST1-1,L094D-*
12240 ;ERROR 13 - OUT OF BOUND INDIRECT ADDR
12250        .BYTE RERR,$0D
12260        .BYTE $FF ;JMP TO LINOUT
12270 L0920  .BYTE INC0
12280        .BYTE CHK0+',,L092A-*
12290        .BYTE COPY,$62,$56
12300        .DBYTE L0948+OFFSET
12310 L092A  .BYTE INC0
12320        .BYTE COPY,$60,$56
12330        .BYTE CHK0+'Y,L0910-*
12340        .BYTE $FE ;JMP TO L08E6
12350 L0934  .BYTE INC0
12360        .BYTE COPY,$64,$56
12370        .BYTE CHK0+'X,L0946-*
12380        .BYTE COPY,$66,$56
12390        .BYTE CHK0+'Y,L0946-*
12400 ;ERROR 8 - INVALID INDEX - NOT X OR Y
12410        .BYTE RERR,$08
12420        .BYTE $FF ;JMP TO LINOUT
12430 L0946  .BYTE INC0
12440 L0948  .BYTE CHK0+SPC,L094D-*
12450        .BYTE $FE ;JMP TO L08E6
12460 L094D  .DBYTE L0D3D+OFFSET
12470 L0950  .BYTE INC0
12480        .BYTE CHK0+SPC,L094D-*
12490        .BYTE DECR,$00
12500        .DBYTE L08D5+OFFSET
12510 ;
12520 ;OPCODE $05 - INSTRUCTION LENGTH = 1
12530 ;SKIP SPACES IN INPUT STREAM
12540 ;ENTRY POINT IS AT L0961
12550 L095F  .BYTE INC0 ;INCREMENT CHARACTER POINTER
12560 L0961  .BYTE CHK0+$20,L095F-*
12570        .BYTE RETN
12580 ;
12590 ;OPCODE $18 XX
12600 ;TAKE RECORD OF ERROR NO XX PLUS TEXT POINTER ;
12610 ;A MAXIMUM OF TWO SUCH RECORDS CAN BE KEPT
12620 L0965  LDX NUMERR 
12630        CPX #2
12640        BEQ L0982
12650        ASL A 
12660        LDY PASS
12670        DEY 
12680        BNE L0975
12690        BCC L0982
12700 L0975  LSR A 
12710        STA ERRMSG,X
12720        LDA $00
12730        STA ERRMSG+2,X
12740        INC NUMERR
12750 L0982  JMP L11CF ;ADVANCE INTERPRETIVE POINTER AN
12760 ;
12770 ;ENTRY FOUND IN TABLE
12780 L0A20  TXA 
12790        LSR A
12800        TAY 
12810        LDA INSTYP,Y
12820        BCS NOLSR
12830        LSR A
12840        LSR A
12850        LSR A
12860        LSR A
12870 NOLSR  AND #$0F
12880        TAY 
12890        CPY #$0F
12900        BNE L0A2D ;BRANCH IF OPCODE MNEMONIC
12910        JSR L11DC ;EXECUTE P-CODE
12920        .BYTE RET2 ;2ND BYTE OF CALL IS BRANCH
12930 ;OPCODE MNEMONIC FOUND
12940 ;LOAD DRTYPE ACCORDING TO INSTR TYPE
12950 L0A2D  LDA L0DD5,Y
12960        STA DRTYPE
12970        LDA L0DE3,Y
12980        STA DRTYPE+1
12990        LDA INSBAS-2,X ;GET OPCODE BASE
13000        STA $20
13010        JSR L11DC ;EXECUTE P-CODE
13020        .BYTE RET3 ;3RD BYTE OF CALL IS BRANCH
13030 ;
13040 ;OPCODE $07 - INSTRUCTION LENGTH = 5
13050 ;SEARCH FOR LABEL, AS PART OF EXPRESSION
13060 ;BYTES 2, 3, AND 4 ARE RELATIVE BRANCH OFFSETS
13070 ;NO BRANCH:  LABEL FOUND ;VALUE IN LABVAL
13080 ;BYTE 2:  A, X, Y, S, OR P HAS BEEN FOUND
13090 ;BYTE 3:  OPCODE MNEMONIC FOUND
13100 ;BYTE 4:  UNDEFINED LABEL
13110 L0985  .BYTE EX65
13120        DEY 
13130        .BYTE $24
13140 ;
13150 ;OPCODE $06 - INSTRUCTION LENGTH = 5
13160 ;SEARCH FOR LABEL, AS L-VALUE
13170 ;BYTES 2, 3, AND 4 ARE RELATIVE BRANCH OFFSETS
13180 ;NO BRANCH:  LABEL FOUND ;VALUE IN LABVAL
13190 ;BYTE 2:  A, X, Y, S, OR P HAS BEEN FOUND
13200 ;BYTE 3:  OPCODE MNEMONIC FOUND
13210 ;BYTE 4:  UNDEFINED LABEL
13220 L0989  .BYTE EX65
13230        STY $30 ;1 FOR INSTRUCTION $06 AND 0 FOR $
13240        STX $32 ;ASSUME LABEL DEFINED BY DEFAULT
13250 ;LABEL IS STORED IN 4 BYTES STARTING AT LABL40
13260        LDA LABL40+2
13270        ORA LABL40+3
13280        BNE L09B9 ;BRANCH IF LABEL 4 CHARS OR LONG
13290 ;USE BINARY SEARCH TO FIND OPCODE
13300 ;RECORDS ARE 4 BYTES EACH
13310 ;TABLE HAS 63 RECORDS, ALTHOUGH NOT ALL ARE
13320 ;PRESENT IN MNEMLO, INSBAS AND INSTYP.
13330 ;$E4 CONTAINS CURRENT CHOP SIZE
13340        LDA #$20
13350        STA $E4
13360 ;ACC IS THE CURRENT INDEX INTO TABLE
13370 ;$00 CANNOT OCCUR
13380 L0997  LSR $E4
13390        TAX 
13400        LDY MNEMHI-1,X
13410        CPY LABL40+1
13420        BCC L09AE
13430        BNE L09AA
13440        LDY MNEMLO-1,X
13450        CPY LABL40
13460        BCC L09AE
13470        BEQ L0A20 ;ENTRY FOUND IN TABLE
13480 L09AA  SBC $E4
13490        .BYTE $2C
13500 L09AE  ADC $E4
13510        LDX $E4
13520        BNE L0997
13530 ;LABEL IDENTIFIED - NOT OPCODE MNEMONIC
13540 L09B9  JSR L11DC ;EXECUTE P-CODE
13550 ;SUBTRACT CONSTANT OF 5 IN CONST5
13560 ;FROM END OF AVAILABLE MEMORY IN ENDMEM
13570 ;TO PRODUCE POINTER TO NEXT LABEL IN $0C/$0D
13580        .BYTE SUBZ,ENDMEM,CONST5,$0C
13590        .BYTE EX65
13600 L09C1  LDA $0C 
13610        CMP LABTBL
13620        LDA $0D
13630        SBC LABTBL+1
13640        BCC L0A41 ;BRANCH IF OFF END OF LABEL TABL
13650        LDA LABL40+1
13660        CMP ($0C),Y
13670        BNE L09F3 ;GO TO NEXT ENTRY IF NO MATCH
13680        LDA LABL40
13690        CMP ($0C,X)
13700        BNE L09F3 ;GO TO NEXT ENTRY IF NO MATCH
13710        LDY #$03
13720        LDA ($0C),Y
13730        CMP #$FE
13740        BCC L09E8
13750 ;LABEL NOT COMPLETELY DEFINED
13760        STA $32
13770        LDY #$05
13780        LDA ($0C),Y
13790        LDY #$03
13800 L09E8  CMP LABL40+3
13810        BNE L09F3 ;GO TO NEXT ENTRY IF NO MATCH
13820        DEY 
13830        LDA LABL40+2
13840        CMP ($0C),Y
13850        BEQ L0A02
13860 ;GO TO PREVIOUS ENTRY IN LABEL TABLE
13870 ;CONST6/$F5 CONTAINS CONSTANT OF 6
13880 L09F3  JSR L11DC ;EXECUTE P-CODE
13890        .BYTE SUBZ,$0C,CONST6,$0C
13900        .BYTE EX65
13910        STX $32 ;ASSUME LABEL DEFINED BY DEFAULT
13920        BNE L09C1 ;ALWAYS BRANCHES
13930 ;
13940 L0A02  LDA $32
13950        BNE L0A47 ;BRANCH IF LABEL UNDEFINED
13960 ;BRANCH IF LABEL IS PART OF R-VALUE
13970        LDA $30
13980        BEQ L0A44
13990 ;
14000 ;LABEL FOUND AND IT'S AN L-VALUE
14010 ;IF IT'S NOT FOLLOWED BY AN '=' SIGN,
14020 ;CHECK ITS VALUE AGAINST PRESENT LOCATION
14030        JSR L11DC ;EXECUTE P-CODE
14040        .BYTE ADDZ,$0C,CONST4,$0C ;$0C/$0D POINTS 
14050 L113C  .BYTE CLAS,L1140-*,L1140-*,L1140-*
14060 L1140  .BYTE COPY,$04,$00
14070        .BYTE CHK6+'=,L0A1F-*
14080        .BYTE BMOV,CONST2,$0C,CNST7E ;MOVE ADDR FI
14090 L0A18  .BYTE BEQU,ASMADR,LABVAL,L0A1F-*
14100 ;ERROR IF ADDRESS FIELD NOT EQUAL TO ASMADR/ASMAD
14110 ;"LABEL PREVIOUSLY DEFINED"
14120 ;ERROR 12 - LABEL PREVIOUSLY DEFINED
14130        .BYTE RERR,$0C
14140 L0A1F  .BYTE RETN
14150 ;
14160 ;CREATE NEW SYMBOL TABLE ENTRY OR
14170 ;RECORD SYMBOL TABLE OVERFLOW
14180 L0A41  LDA $7C 
14190        BNE L05F5 ;BRANCH IF TABLE ALREADY OVERFLO
14200        JSR L11DC ;EXECUTE P-CODE
14210        .BYTE BGEQ,$0C,ENDTXT,L0C22-* ;CHECK FOR 
14220 ;ERROR 25 - SYMBOL TABLE OVERFLOW
14230        .BYTE RERR,$99
14240        .BYTE SET1,$7C ;SET SYM TABLE OVERFLOW FLA
14250        .BYTE RET4 ;RETURN - 4TH BYTE OF CALL IS O
14260 L0C22  .BYTE COPY,$0C,LABTBL ;UPDATE START OF TAB
14270        .BYTE BMOV,CONST4,CNST6C,$0C ;COPY UP BASE
14280        .BYTE ADDZ,$0C,CONST4,$32
14290        .BYTE BMOV,CONST2,CNST44,$32 ;COPY UP VALU
14300        .BYTE EX65
14310        LDA $30
14320        BNE L05F5 ;RETURN IF L-VALUE ;
14330 ;LABEL IS PART OF R-VALUE SO MARK IT AS
14340 ;BEING UNDEFINED
14350        LDA LABL40+3
14360        LDY #$05
14370        STA ($0C),Y
14380        LDA #$FF
14390        LDY #$03
14400        STA ($0C),Y
14410 L05F5  JSR L11DC ;EXECUTE P-CODE
14420        .BYTE RET4 ;RETURN - 4TH BYTE OF CALL IS O
14430 ;LABEL DEFINED, AND IS PART OF R-VALUE
14440 ;MOVE ADDRESS FIELD TO LABVAL
14450 L0A44  JSR L11DC ;EXECUTE P-CODE
14460        .BYTE ADDZ,$0C,CONST4,$0C
14470        .BYTE BMOV,CONST2,$0C,CNST7E
14480        .BYTE RETN
14490 ;UNDEFINED LABEL FOUND IN LABEL TABLE
14500 L0A47  LDY #$04
14510        LDX $30
14520        BEQ L0A50 ;BRANCH IF PART OF R-VALUE
14530 ;LABEL IS BEING CONSIDERED AS L-VALUE
14540        EOR #$FE
14550 ;BRANCH IF UNDEFINED AND IT WAS PREVIOUSLY ONLY R
14560        BNE L1210
14570 ;OTHERWISE IT'S IN ZERO PAGE
14580        STA $7F
14590        LDA ($0C),Y
14600        STA LABVAL
14610        JSR L11DC ;EXECUTE P-CODE
14620        .DBYTE L0A18+OFFSET ;CHECK IT'S NOT BEEN R
14630 L1210  LDA ASMADR+1
14640        BEQ L1224 ;BRANCH TO MARK IT AS ZERO PAGE
14650        INY 
14660        STA ($0C),Y
14670        DEY 
14680        LDA ASMADR
14690        STA ($0C),Y
14700        LDA LABL40+3
14710 L121E  DEY 
14720        STA ($0C),Y
14730        JMP L0B7B
14740 L1224  LDA ASMADR
14750        STA ($0C),Y
14760        LDA #$FE
14770        BNE L121E
14780 ;UNDEFINED LABEL IS R-VALUE
14790 L0A50  EOR #$FE
14800        BNE L05F5 ;EXIT IF IT'S NEVER BEEN R-VALUE
14810        STA $7F ;PUT ITS PAGE ZERO ADDRESS INTO $7
14820        LDA ($0C),Y
14830        STA LABVAL
14840        LDA $ED ;SET FLAG TO INDICATE THAT THIS HA
14850        ORA #%01000000
14860        STA $ED
14870        JMP L02BC ;RETURN FROM P-CODE SUBROUTINE
14880 ;
14890 ;OPCODE $23 - INSTRUCTION LENGTH = 1
14900 ;DECOMPRESS TEXT POINTED TO BY TXTPOS/TXTPOS+1,
14910 ;AND STORE IT STARTING FROM $02/$03
14920 L0A60  STX $E4
14930        INY 
14940 L0A63  LDX #$FF
14950        LDA (TXTPOS),Y
14960        BPL L0A6C
14970        TAX 
14980        LDA $28
14990 L0A6C  STY $E5
15000        LDY $E4
15010 L0A70  STA ($02),Y
15020        INY 
15030        INX 
15040        BMI L0A70
15050        STA $28
15060        STY $E4
15070        LDY $E5
15080        INY 
15090        CMP #$0D
15100        BNE L0A63
15110        JMP L11CF ;GO TO NEXT INSTRUCTION
15120 ;***********************************
15130 ;MULTIPLY SUBROUTINE
15140 ;16-BIT QUANTITIES IN ZERO PAGE POINTED TO
15150 ;BY A AND Y ARE MULTIPLIED TOGETHER, AND
15160 ;THE 16-BIT RESULT IS PUT INTO THE TWO
15170 ;LOCATIONS POINTED TO BY X.  ALSO, THE
15180 ;16-BIT QUANTITY SPECIFIED BY TMPLOC+1(LO) AND
15190 ;$EC(HI) IS ADDED ON.  Z FLAG CLEARED IF RESULT
15200 ;IS GREATER THAN $FFFF.
15210 L0A84  STX $E5
15220        TAX 
15230        LDA $00,X
15240        STA $E8
15250        LDA $01,X
15260        LSR A 
15270        STA $E9
15280        LDA #$10
15290        STA TMPLOC
15300        LSR $E8
15310 L0AA0  BCC L0AB1
15320        CLC 
15330        LDA TMPLOC+1
15340        ADC $0000,Y
15350        STA TMPLOC+1
15360        LDA $EC
15370        ADC $0001,Y
15380        STA $EC
15390 L0AB1  ROR $EC
15400        ROR TMPLOC+1
15410        ROR $E9
15420        ROR $E8
15430        DEC TMPLOC
15440        BNE L0AA0
15450        LDX $E5
15460        LDA $E8
15470        STA $00,X
15480        LDA $E9
15490        STA $01,X
15500 ;CLEAR Z FLAG IF OVERFLOW
15510        LDA TMPLOC+1
15520        ORA $EC
15530        RTS 
15540 ;
15550 ;OPCODE $0A - 2ND BYTE IS BRANCH OFFSET
15560 L0AF0  .BYTE EX65
15570        TXA 
15580        LDX #$04
15590 L0AF4  STA $6B,X
15600        DEX 
15610        BNE L0AF4
15620        STA $27
15630        STA $29
15640        INY 
15650        STY $46
15660        LDA #LABL40
15670        STA $47
15680 L0B08  LDY #$00
15690        LDA ($00),Y
15700 L0B0C  CMP L0B80,X
15710        BMI L0B14
15720        CMP L0B85,X
15730        BPL L0B14
15740        LDY $27
15750        CPY #$06
15760        BCS L0B61
15770        SBC L0B8A,X
15780        STA $28
15790        LDX $47
15800        LDY $46
15810        BNE L0B48
15820        CLC 
15830        ADC $00,X
15840        STA $00,X
15850        BCC L1264
15860        INC $01,X
15870 L1264  INC $47
15880        INC $47
15890        LDA #$02
15900        STA $46
15910        BNE L0B61
15920 L0B48  LDA $00,X ;SET UP EXISTING TOTAL
15930        STA TMPLOC+1
15940        LDA $01,X
15950        STA $EC
15960        LDA L0B8F-1,Y ;SET UP MULTIPLIER (Y=1 OR 2
15970        STA $E8
15980        LDA L0B91-1,Y
15990        STA $E9
16000        LDA #$E8 ;POINTER TO MULTIPLIER
16010        LDY #$28 ;POINTER TO ENCODED CHARACTER
16020        JSR L0A84 ;MULTIPLY
16030        DEC $46
16040 L0B61  INC $00
16050        BNE L0B67
16060        INC $01
16070 L0B67  INC $27
16080        LDX #$03
16090        BNE L0B08 ;ALWAYS BRANCHES
16100 L0B6B  CMP #$07
16110        BPL L0B74
16120        JSR L11DC ;EXECUTE P-CODE
16130        .BYTE RET2 ;RETURN - 2ND BYTE OF CALL IS O
16140 L0B74  JSR L11DC
16150 ;ERROR 10 - LABEL LONGER THAN 6 CHARS
16160        .BYTE RERR,$0A
16170        .BYTE RET2 ;RETURN - 2ND BYTE OF CALL IS O
16180 L0B14  DEX 
16190        BPL L0B0C
16200        LDA $27
16210        BNE L0B6B
16220 L0B7B  JSR L11DC
16230        .BYTE RETN
16240 L0B80  .BYTE $41,$30,$2E,$24
16250 L0B85  .BYTE $5B,$3B,$2F,$25 
16260 L0B8A  .BYTE $3F,$14,$07,$FC
16270 L0B8F  .BYTE $28,$40
16280 L0B91  .BYTE $00,$06
16290 ;
16300 ;OPCODE $17 XX - PRINT CONTENTS OF LOCATION
16310 ;XX AS 2-DIGIT HEX NUMBER 
16320 L0BE5  TAX 
16330        LDA $00,X
16340        JSR HEXOUT
16350 ;ADVANCE IP AND MOVE TO NEXT INSTR
16360        JMP L11CF
16370 ;
16380 ;OPCODE $09 - INSTRUCTION LENGTH = 2
16390 ;EVALUATE EXPRESSION - RESULT IN LABVAL
16400 ;BRANCH ON SECOND BYTE IF ERROR
16410 L0C30  .BYTE SET0,$EC ;SET TO ZERO
16420        .BYTE SET0,$36
16430        .BYTE SET0,NUMVAL ;SET TO ZERO
16440 L0C39  .BYTE CHK0+SPC,L0CB4-* ;ERROR IF CR OR SP
16450        .BYTE RLBL,L0C5D-* ;BRANCH IF LABEL FOUND
16460        .BYTE ADDZ,CNST10,CONST6,$34 ;$34/$35 IS B
16470        .BYTE CHK0+'$,L0C64-* ;BRANCH IF HEX NUMB
16480        .BYTE ADDZ,CONST3,CONST5,$34 ;BASE = 8
16490        .BYTE CHK0+'@,L0C64-* ;BRANCH IF OCTAL NU
16500        .BYTE COPY,CONST2,$34 ;BASE = 2
16510        .BYTE CHK0+'%,L0C64-* ;BRANCH IF BINARY N
16520        .BYTE CHK0+$27,L0CBD-* ;BRANCH IF QUOTE
16530        .BYTE CHK0+'*,L0EFD-* ;BRANCH IF CURRENT 
16540        .BYTE COPY,CNST10,$34 ;OTHERWISE ASSUME BA
16550        .DBYTE L0C66+OFFSET
16560 ;HANDLE '*' - LOCATION COUNTER
16570 L0EFD  .BYTE COPY,ASMADR,LABVAL
16580        .DBYTE L0EDE+OFFSET
16590 ;LOOK UP VALUE OF LABEL - BRANCH IF ERROR
16600 L0C5D  .BYTE LEXP,L0CD6-*,L0CD6-*,L0CD6-*
16610        .BYTE $FB ;JMP TO L0CDC
16620 ;PROCESS NUMERIC LITERAL
16630 L0C64  .BYTE INC0 ;GO TO NEXT CHAR IF NOT DECI
16640 L0C66  .BYTE SET0,LABVAL ;SET RESULT TO ZERO
16650        .BYTE SET0,LABL40 ;LABL40 AND LABL40+1 USE
16660        .BYTE EX65
16670 L0C6D  LDY #$00
16680        LDA ($00),Y ;GET NEXT CHARACTER
16690        SEC 
16700        LDX $34
16710        SBC #$30
16720        BMI L0CA2 ;BRANCH IF NOT VALID
16730        CMP $34
16740        BPL L0C95 ;BRANCH IF OUT OF RANGE
16750 L0C78  INC LABL40 ;CHAR COUNT
16760        STA TMPLOC+1
16770        LDA #$00
16780        STA $EC
16790        LDX #LABVAL
16800        LDY #LABVAL
16810        LDA #$34
16820 ;MULTIPLY RESULT IN LABVAL BY 10 AND
16830 ;ADD ON NEW DIGIT
16840        JSR L0A84 
16850        BEQ L0C8D ;BRANCH IF NO OVERFLOW
16860        INC LABL40+1 ;OVERFLOW COUNT
16870 L0C8D  INC $00 ;INCREMENT POINTER
16880        BNE L0C6D
16890        INC $01
16900        BNE L0C6D ;THEN DO NEXT DIGIT
16910 ;DIGIT SEEMS TO BE OUT OF RANGE, BUT
16920 ;CHECK FIRST TO SEE IF IT IS VALID HEX
16930 L0C95  CPX #$10
16940        BNE L0CA2
16950 ;CARRY IS SET ANYWAY AFTER CPX 
16960        SBC #$07
16970        BMI L0CA2
16980        CMP #$10
16990        BMI L0C78
17000 ;DIGIT DEFINITELY OUT OF RANGE
17010 L0CA2  LDA LABL40 ;CHECK IF IT'S FIRST CHARACTER
17020        BEQ L0CB1 ;IF SO, "INVALID EXPRESSION"
17030        LDA LABL40+1 ;CHECK IF OVERFLOW HAS OCCURR
17040        BEQ L0CB8 ;IF NOT, VALID TERMINATION OF NU
17050        JSR L11DC ;EXECUTE P-CODE
17060 ;ERROR 3 - ADDRESS NOT VALUD
17070        .BYTE RERR,$03
17080        .BYTE $FB ;JMP TO L0CDC
17090 L0CB1  JSR L11DC ;EXECUTE P-CODE
17100 ;ERROR 7 - INVALID EXPRESSION
17110 L0CB4  .BYTE RERR,$07
17120        .BYTE RET2 ;RETURN - 2ND BYTE OF CALL IS O
17130 L0CB8  JSR L11DC ;EXECUTE P-CODE
17140        .BYTE $FB ;JMP TO L0CDC
17150 ;PROCESS SINGLE QUOTE CHARACTER
17160 L0CBD  .BYTE INC0
17170        .BYTE SET0,LABVAL ;SET LABVAL TO ZERO
17180        .BYTE MOVB,CNST7E ;AND PUT BYTE INTO LABVA
17190 L0EDE  .BYTE INC0 ;MOVE ON TO NEXT CHAR
17200        .BYTE $FB ;JMP TO L0CDC
17210 ;PROCESS UNDEFINED LABEL
17220 L0CD6  .BYTE ADDZ,CONST1,$ED,$ED
17230 ;ERROR 18 - UNDEFINED LABEL
17240        .BYTE RERR,$12
17250        .BYTE $FC ;JMP TO L0D11
17260 ;LOOK TO SEE IF THERE'S AN OPERATOR
17270 ;SET UP $06/$07 TO POINT TO PREVIOUS OPERATOR
17280 L0CDC  .BYTE COPY,$3A,$06
17290        .BYTE CHK6+'/,L0D07-* ;DIVIDE
17300        .BYTE CHK6+'*,L0CF4-* ;MULTIPLY
17310        .BYTE CHK6+'-,L0CEE-* ;SUBTRACT
17320 ;MUST BE '+' - ADD LABVAL TO NUMVAL
17330        .BYTE ADDZ,NUMVAL,LABVAL,NUMVAL
17340        .BYTE $FC ;JMP TO L0D11
17350 ;SUBTRACT - SUBTRACT LABVAL FROM NUMVAL
17360 L0CEE  .BYTE SUBZ,NUMVAL,LABVAL,NUMVAL
17370        .BYTE $FC ;JMP TO L0D11
17380 ;MULTIPLY NUMVAL BY LABVAL
17390 L0CF4  .BYTE EX65
17400        LDA #NUMVAL 
17410        LDY #LABVAL
17420        STX TMPLOC+1
17430        STX $EC
17440        TAX 
17450        JSR L0A84 ;MULTIPLY
17460        JMP L0D02
17470 ;DIVIDE NUMVAL BY LABVAL
17480 L0D07  .BYTE COPY,NUMVAL,$26
17490        .BYTE EX65
17500        LDX #$26
17510        LDY #LABVAL
17520        LDA #NUMVAL
17530        JSR L052A
17540 L0D02  JSR L11DC ;EXECUTE P-CODE
17550 ;LOOK FOR NEXT OPERATOR -
17560 ;GO TO L0D1F IF FOUND
17570 L0D11  .BYTE CHK0+'+,L0D1F-*
17580        .BYTE CHK0+'-,L0D1F-*
17590        .BYTE CHK0+'*,L0D1F-*
17600        .BYTE CHK0+'/,L0D1F-*
17610 ;OTHERWISE, EXIT
17620 ;SET TOP BIT OF $ED TO 1
17630 ;IF RESULT $0100 OR GREATER.
17640        .BYTE BLES,NUMVAL,CONST1-1,L0D30-*
17650        .BYTE ADDZ,CNST80,$ED,$ED
17660 L0D30  .BYTE RETN
17670 ;OPERATOR FOUND - SO MOVE IT INTO
17680 ;LOCATION POINTED TO BY $3A/$3B
17690 L0D1F  .BYTE MOVB,$3A
17700        .BYTE INC0
17710        .DBYTE L0C39+OFFSET ;MOVE ON TO NEXT CHARA
17720 L0D34  JSR L11DC ;EXECUTE P-CODE
17730 ;ERROR 5 - ILLEGAL OPERAND TYPE FOR THIS INSTR
17740        .BYTE RERR,$05
17750        .BYTE $FF ;JMP TO LINOUT
17760 L0D3D  .BYTE EX65
17770        LDY #$FF 
17780        LDA DRTYPE+1
17790        AND $57
17800        BNE L0D4F
17810        LDY #$07
17820        LDA DRTYPE
17830        AND $56
17840        BEQ L0D34
17850 L0D4F  ROL A 
17860        INY 
17870        BCC L0D4F
17880        CPY #$08
17890        BPL L0DB1
17900        LDA L0DFD,Y
17910        AND #$2A
17920        BNE L0D90
17930        TYA 
17940        BNE L0DB1
17950        LDA #$3F
17960        BIT $ED
17970        BNE L0DB1
17980        JSR L11DC ;EXECUTE P-CODE
17990        .BYTE SUBZ,NUMVAL,ASMADR,NUMVAL
18000        .BYTE SUBZ,NUMVAL,CONST2,NUMVAL
18010        .BYTE BLES,NUMVAL,CNST80,L0D8C-*
18020        .BYTE ADDZ,NUMVAL,CNST80,$1C
18030        .BYTE BLES,$1C,CNST80,L0D8C-*
18040 ;ERROR 16 - RELATIVE BRANCH OUT OF RANGE
18050        .BYTE RERR,$10
18060        .BYTE DECR,INSTLN
18070        .BYTE $FF ;JMP TO LINOUT
18080 L0D90  LDA $ED
18090        ASL A 
18100        BNE L0DA6
18110        BCC L0DB1
18120        INY 
18130        LDA L0DFD,Y
18140        AND DRTYPE+1
18150        BNE L0DB1
18160        JSR L11DC ;EXECUTE P-CODE
18170 ;ERROR 3 - ADDRESS NOT VALID
18180        .BYTE RERR,$03
18190        .BYTE $FF ;JMP TO LINOUT
18200 L0DA6  INY 
18210        LDA L0DFD,Y
18220        STY DRTYPE
18230        AND DRTYPE+1
18240        BNE L0DCE
18250        .BYTE $24
18260 L0D8C  .BYTE EX65
18270        DEY 
18280 L0DB1  LDA $20
18290        LSR A 
18300        LDA L0E0D,Y
18310        BCS L0DBC
18320        LDA L0E19,Y
18330 L0DBC  CLC 
18340        ADC $20
18350        STA INSTRN
18360        LDA L0DF1,Y
18370        STA INSTLN
18380        JSR L11DC ;EXECUTE P-CODE
18390        .BYTE COPY,NUMVAL,INSTRN+1
18400        .BYTE $FF ;JMP TO LINOUT
18410 L0DCE  JSR L11DC ;EXECUTE P-CODE
18420 ;ERROR 19 - FWD REF TO PAGE ZERO MEMORY
18430        .BYTE RERR,$13
18440        .BYTE EX65
18450        LDY DRTYPE 
18460        JMP L0DB1
18470 L0DD5  .BYTE $60,$60,$00,$80,$00,$00,$00
18480        .BYTE $00,$00,$00,$10,$00,$00,$00
18490 L0DE3  .BYTE $7D,$3D,$3C,$3C,$73,$32,$7C
18500        .BYTE $38,$70,$30,$10,$10,$00,$80
18510 L0DF1  .BYTE $02,$02,$02,$03,$02
18520        .BYTE $03,$02,$03,$01,$02,$02,$03
18530 L0DFD  .BYTE $80,$40,$20,$10
18540        .BYTE $08,$04,$02,$01
18550 L0E0D  .BYTE $00,$08,$04,$0C,$14,$1C
18560        .BYTE $00,$18,$00,$10,$00,$00
18570 L0E19  .BYTE $00,$00,$04,$0C,$14,$1C
18580        .BYTE $14,$1C,$08,$00,$00,$2C
18590 ;
18600 ;OUTPUT ACCUMLATOR AS HEX NUMBER, BUT
18610 ;ADD ONTO CHKSUM FIRST
18620 HEXCHK PHA 
18630        CLC 
18640        ADC CHKSUM
18650        STA CHKSUM
18660        BCC L1942
18670        INC CHKSUM+1
18680 L1942  PLA 
18690 ;OUTPUT ACCUMLATOR AS HEX NUMBER
18700 HEXOUT PHA 
18710        LSR A 
18720        LSR A 
18730        LSR A 
18740        LSR A 
18750        JSR HEXDIG ;PRINT SINGLE HEX DIGIT IN ACCU
18760        PLA 
18770        AND #$0F
18780 ;PRINT SINGLE HEX DIGIT IN ACCUMULATOR
18790 HEXDIG ORA #'0
18800        CMP #'9+1
18810        BCC L132E
18820        ADC #6
18830 L132E  JMP COUT
18840 ;A2 - ASSEMBLE TO HEX FILE
18850 A2OUT  .BYTE EX65
18860        DEY ;Y = 0
18870        LSR ASMBRK
18880        LDA INSTLN
18890        STA $E4
18900        BCS FLUSHB
18910 L10DA  DEC $E4
18920        BMI ADDLNP
18930        LDX A2BLEN
18940        LDA INSTRN,Y
18950        STA A2BUFF,X
18960        INY 
18970        INX 
18980        STX A2BLEN
18990        CPX #24 ;BUFFER IS MAX 24 CHARS
19000        BNE L10DA
19010 ;FLUSH THE BUFFER FOR A2 OPTION
19020 FLUSHB LDX A2BLEN
19030        BEQ L126A
19040        LDA #';
19050        JSR COUT ;PRINT CHARACTER IN ACC
19060 ;PRINT NUMBER OF BYTES AND START ADDR
19070        TXA 
19080        JSR HEXCHK
19090        LDX #2
19100 L10FF  LDA BUFADR-1,X
19110        JSR HEXCHK
19120        DEX 
19130        BNE L10FF
19140 ;PRINT DATA BYTES
19150 L1107  LDA A2BUFF,X
19160        JSR HEXCHK
19170        INX 
19180        DEC A2BLEN
19190        BNE L1107
19200 ;PRINT CHECKSUM
19210        LDA CHKSUM+1
19220        JSR HEXOUT
19230        LDA CHKSUM
19240        JSR HEXOUT
19250        JSR NEWLIN
19260 ;PRINT SIX NULL CHARACTERS
19270        LDX #$06
19280 L1262  LDA #$00
19290        JSR COUT ;PRINT CHARACTER IN ACC
19300        DEX 
19310        BNE L1262
19320 L126A  STX CHKSUM
19330        STX CHKSUM+1
19340 ;SET START ADDRESS OF NEXT BLOCK
19350        CLC 
19360        TYA 
19370        ADC ASMADR
19380        STA BUFADR
19390        LDA #$00
19400        ADC ASMADR+1
19410        STA BUFADR+1
19420        JMP L10DA
19430 ;
19440 ADDLNP JSR L11DC ;EXECUTE P-CODE
19450 ;ADD INSTRUCTION LENGTH ONTO CURRENT
19460 ;LOCATION THEN EXIT
19470 ADDLEN .BYTE ADDZ,ASMADR,INSTLN,ASMADR
19480        .BYTE RETN
19490 ;
19500 ;A2 OR A3 OPTIONS
19510 A2ORA3 .BYTE BEQU,ASMOPT,CONST2,A2OUT-*
19520 ;
19530 ;A3 - ASSEMBLE TO MEMORY
19540        .BYTE ADDZ,ASMADR,ASMOFS,$1C ;ADD OFFSET
19550        .BYTE BMOV,INSTLN,CNST50,$1C ;COPY INSTR T
19560        .DBYTE L0E34+OFFSET ;CHECK FOR ASM ERRORS
19570 ;
19580 ;OPCODE $08 - INSTRUCTION LENGTH = 1
19590 ;OUTPUT CURRENT ASSEMBLER INSTRUCTION
19600 ;RELEVANT LOCATIONS:
19610 ;NUMERR = ZERO IF NO ERRORS ON THIS LINE
19620 ;
19630 ;GO TO A2ORA3 IF A2/A3 OPTION, AND PASS 2
19640 L10B3  .BYTE BNEQ,PASS,CONST2,L10BD-*
19650        .BYTE BGEQ,ASMOPT,CONST2,A2ORA3-*
19660 ;
19670 ;GO TO ADDLEN IF ERROR, OR IF IT'S BOTH PASS 2 AN
19680 ;A LISTING IS REQUIRED.
19690 L10BD  .BYTE BEQU,PASS,CONST1,L0E34-* ;BR IF PAS
19700        .BYTE BEQU,ASMOPT,CONST0,L0E39-* ;BR IF L
19710 ;GO TO ADDLEN IF NO ERRORS
19720 L0E34  .BYTE BEQU,CONST0,NUMERR,ADDLEN-*
19730 ;
19740 ;OUTPUT LINE OF ASSEMBLY LISTING
19750 L0E39  .BYTE PDEC,LINENO ;PRINT LINE NO
19760        .BYTE BEQU,PASS,CONST1,L0E6A-* ;BRANCH IF
19770        .BYTE MESG,' ',$00 ;PRINT SPACE
19780        .BYTE PHEX,ASMADR+1 ;PRINT CURRENT ADDRESS
19790        .BYTE PHEX,ASMADR
19800        .BYTE MESG,' ',$00 ;PRINT SPACE
19810 ;
19820 ;PRINT 0, 1, 2 OR 3 BYTES OF OBJECT CODE,
19830 ;PLUS SPACES TO PAD IT OUT
19840        .BYTE BNEQ,INSTLN,CONST0,PRINST-*
19850        .BYTE MESG,'  ',$00
19860 TWOSPC .BYTE MESG,'  ',$00
19870 ONESPC .BYTE MESG,'  ',$00
19880 ;
19890 ;IF PRFLAG IS SET THEN THE LINE HAS ALREADY
19900 ;BEEN PRINTED - APPLIES FOR DIRECTIVES, WHICH
19910 ;MAY PRODUCE MORE THAN ONE LINE OF OUTPUT.
19920 L0E6A  .BYTE BEQU,CONST1,PRFLAG,L0EC5-*
19930        .BYTE MESG,' ',$00
19940        .BYTE PLIN,$02 ;PRINT OUT LINE OF TEXT 
19950        .BYTE SET1,PRFLAG ;SET PRFLAG
19960 ;
19970 ;PROCESS ASSEMBLY ERRORS
19980 L0E77  .BYTE GERR,$20,ADDLEN-* ;BR IF NO ERRORS
19990        .BYTE ADDZ,$06,CONST6,$06 ;ADD 6 TO $06/$0
20000        .BYTE BEQU,PASS,CONST1,L0E9E-* ;BRANCH IF
20010        .BYTE ADDZ,$06,CNST12,$06 ;ADD 12 TO $06/$
20020 L0E9E  .BYTE PERR,'E#',$00
20030        .BYTE PDEC,$20 ;PRINT ERROR NUMBER
20040 L0EC5  .BYTE MESG,$0D ;END OF LINE
20050        .DBYTE L0E77+OFFSET ;LOOK FOR NEXT ERROR
20060 ;
20070 PRINST .BYTE PHEX,INSTRN
20080        .BYTE BEQU,INSTLN,CONST1,TWOSPC-*
20090        .BYTE PHEX,INSTRN+1
20100        .BYTE BEQU,INSTLN,CONST2,ONESPC-*
20110        .BYTE PHEX,INSTRN+2
20120        .DBYTE L0E6A+OFFSET
20130 ;
20140 ;TABLE OF OPCODE MNEMONICS
20150 ;LOW BYTE OF MNEMONIC IN BASE-40
20160 MNEMLO .BYTE $40 ;A
20170        .BYTE $E3 ;ADC
20180        .BYTE $74 ;AND
20190        .BYTE $44 ;ASL
20200        .BYTE $FB ;BCC
20210        .BYTE $0B ;BCS
20220        .BYTE $59 ;BEQ
20230        .BYTE $FC ;BIT
20240        .BYTE $91 ;BMI
20250        .BYTE $B5 ;BNE
20260        .BYTE $0C ;BPL
20270        .BYTE $5B ;BRK
20280        .BYTE $F3 ;BVC
20290        .BYTE $03 ;BVS
20300        .BYTE $A3 ;CLC
20310        .BYTE $A4 ;CLD
20320        .BYTE $A9 ;CLI
20330        .BYTE $B6 ;CLV
20340        .BYTE $D8 ;CMP
20350        .BYTE $58 ;CPX
20360        .BYTE $59 ;CPY
20370        .BYTE $CB ;DEC
20380        .BYTE $E0 ;DEX
20390        .BYTE $E1 ;DEY
20400        .BYTE $AA ;EOR
20410        .BYTE $73 ;INC
20420        .BYTE $88 ;INX
20430        .BYTE $89 ;INY
20440        .BYTE $98 ;JMP
20450        .BYTE $8A ;JSR
20460        .BYTE $A1 ;LDA
20470        .BYTE $B8 ;LDX
20480        .BYTE $B9 ;LDY
20490        .BYTE $0A ;LSR
20500        .BYTE $E8 ;NOP
20510        .BYTE $91 ;ORA
20520        .BYTE $41 ;PHA
20530        .BYTE $50 ;PHP
20540        .BYTE $E1 ;PLA
20550        .BYTE $F0 ;PLP
20560        .BYTE $E4 ;ROL
20570        .BYTE $EA ;ROR
20580        .BYTE $A9 ;RTI
20590        .BYTE $B3 ;RTS
20600        .BYTE $13 ;SBC
20610        .BYTE $8B ;SEC
20620        .BYTE $8C ;SED
20630        .BYTE $91 ;SEI
20640        .BYTE $E1 ;STA
20650        .BYTE $F8 ;STX
20660        .BYTE $F9 ;STY
20670        .BYTE $40 ;TAX
20680        .BYTE $41 ;TAY
20690        .BYTE $10 ;TSX
20700        .BYTE $C1 ;TXA
20710        .BYTE $D3 ;TXS
20720        .BYTE $E9 ;TYA
20730 ;THESE LAST SIX BYTES ARE NOT NEEDED
20740 ;BECAUSE NO BASE-40 ENCODING CAN
20750 ;EXCEED $FF00.
20760 ;.BYTE $FF ;NULL
20770 ;.BYTE $FF ;NULL
20780 ;.BYTE $FF ;NULL
20790 ;.BYTE $FF ;NULL
20800 ;.BYTE $FF ;NULL
20810 ;.BYTE $FF ;NULL
20820 ;
20830 ;TABLE OF OPCODE MNEMONICS
20840 ;HIGH BYTE OF MNEMONIC IN BASE-40
20850 MNEMHI .BYTE $06 ;A
20860        .BYTE $06 ;ADC
20870        .BYTE $08 ;AND
20880        .BYTE $09 ;ASL
20890        .BYTE $0C ;BCC
20900        .BYTE $0D ;BCS
20910        .BYTE $0D ;BEQ
20920        .BYTE $0D ;BIT
20930        .BYTE $0E ;BMI
20940        .BYTE $0E ;BNE
20950        .BYTE $0F ;BPL
20960        .BYTE $0F ;BRK
20970        .BYTE $0F ;BVC
20980        .BYTE $10 ;BVS
20990        .BYTE $14 ;CLC
21000        .BYTE $14 ;CLD
21010        .BYTE $14 ;CLI
21020        .BYTE $14 ;CLV
21030        .BYTE $14 ;CMP
21040        .BYTE $15 ;CPX
21050        .BYTE $15 ;CPY
21060        .BYTE $19 ;DEC
21070        .BYTE $19 ;DEX
21080        .BYTE $19 ;DEY
21090        .BYTE $21 ;EOR
21100        .BYTE $3A ;INC
21110        .BYTE $3A ;INX
21120        .BYTE $3A ;INY
21130        .BYTE $40 ;JMP
21140        .BYTE $41 ;JSR
21150        .BYTE $4B ;LDA
21160        .BYTE $4B ;LDX
21170        .BYTE $4B ;LDY
21180        .BYTE $4E ;LSR
21190        .BYTE $59 ;NOP
21200        .BYTE $60 ;ORA
21210        .BYTE $65 ;PHA
21220        .BYTE $65 ;PHP
21230        .BYTE $65 ;PLA
21240        .BYTE $65 ;PLP
21250        .BYTE $72 ;ROL
21260        .BYTE $72 ;ROR
21270        .BYTE $73 ;RTI
21280        .BYTE $73 ;RTS
21290        .BYTE $77 ;SBC
21300        .BYTE $77 ;SEC
21310        .BYTE $77 ;SED
21320        .BYTE $77 ;SEI
21330        .BYTE $79 ;STA
21340        .BYTE $79 ;STX
21350        .BYTE $79 ;STY
21360        .BYTE $7D ;TAX
21370        .BYTE $7D ;TAY
21380        .BYTE $80 ;TSX
21390        .BYTE $80 ;TXA
21400        .BYTE $80 ;TXS
21410        .BYTE $80 ;TYA
21420        .BYTE $FF ;NULL
21430        .BYTE $FF ;NULL
21440        .BYTE $FF ;NULL
21450 ;LAST THREE ENTRIES CAN BE REMOVED
21460 ;BECAUSE THEY WILL NEVER BE REACHED BY
21470 ;THE BINARY SEARCH ALGORITHM
21480 ;.BYTE $FF ;NULL
21490 ;.BYTE $FF ;NULL
21500 ;.BYTE $FF ;NULL
21510 ;
21520 ;TABLE OF OPCODE MNEMONICS
21530 ;INSTRUCTION BASE:
21540 INSBAS .BYTE $61 ;ADC
21550        .BYTE $21 ;AND
21560        .BYTE $02 ;ASL
21570        .BYTE $90 ;BCC
21580        .BYTE $B0 ;BCS
21590        .BYTE $F0 ;BEQ
21600        .BYTE $20 ;BIT
21610        .BYTE $30 ;BMI
21620        .BYTE $D0 ;BNE
21630        .BYTE $10 ;BPL
21640        .BYTE $00 ;BRK
21650        .BYTE $50 ;BVC
21660        .BYTE $70 ;BVS
21670        .BYTE $18 ;CLC
21680        .BYTE $D8 ;CLD
21690        .BYTE $58 ;CLI
21700        .BYTE $B8 ;CLV
21710        .BYTE $C1 ;CMP
21720        .BYTE $E0 ;CPX
21730        .BYTE $C0 ;CPY
21740        .BYTE $C2 ;DEC
21750        .BYTE $CA ;DEX
21760        .BYTE $88 ;DEY
21770        .BYTE $41 ;EOR
21780        .BYTE $E2 ;INC
21790        .BYTE $E8 ;INX
21800        .BYTE $C8 ;INY
21810        .BYTE $40 ;JMP
21820        .BYTE $14 ;JSR
21830        .BYTE $A1 ;LDA
21840        .BYTE $A2 ;LDX
21850        .BYTE $A0 ;LDY
21860        .BYTE $42 ;LSR
21870        .BYTE $EA ;NOP
21880        .BYTE $01 ;ORA
21890        .BYTE $48 ;PHA
21900        .BYTE $08 ;PHP
21910        .BYTE $68 ;PLA
21920        .BYTE $28 ;PLP
21930        .BYTE $22 ;ROL
21940        .BYTE $62 ;ROR
21950        .BYTE $40 ;RTI
21960        .BYTE $60 ;RTS
21970        .BYTE $E1 ;SBC
21980        .BYTE $38 ;SEC
21990        .BYTE $F8 ;SED
22000        .BYTE $78 ;SEI
22010        .BYTE $81 ;STA
22020        .BYTE $82 ;STX
22030        .BYTE $80 ;STY
22040        .BYTE $AA ;TAX
22050        .BYTE $A8 ;TAY
22060        .BYTE $BA ;TSX
22070        .BYTE $8A ;TXA
22080        .BYTE $9A ;TXS
22090        .BYTE $98 ;TYA
22100 ;
22110 ;TABLE OF OPCODE MNEMONICS
22120 ;INSTRUCTION TYPE:
22130 INSTYP .BYTE $0F ;A
22140        .BYTE $00 ;ADC, AND
22150        .BYTE $3D ;ASL, BCC
22160        .BYTE $DD ;BCS, BEQ
22170        .BYTE $9D ;BIT, BMI
22180        .BYTE $DD ;BNE, BPL
22190        .BYTE $CD ;BRK, BVC
22200        .BYTE $DC ;BVS, CLC
22210        .BYTE $CC ;CLD, CLI
22220        .BYTE $C0 ;CLV, CMP
22230        .BYTE $88 ;CPX, CPY
22240        .BYTE $2C ;DEC, DEX
22250        .BYTE $C0 ;DEY, EOR
22260        .BYTE $2C ;INC, INX
22270        .BYTE $CA ;INY, JMP
22280        .BYTE $B0 ;JSR, LDA
22290        .BYTE $46 ;LDX, LDY
22300        .BYTE $3C ;LSR, NOP
22310        .BYTE $0C ;ORA, PHA
22320        .BYTE $CC ;PHP, PLA
22330        .BYTE $C3 ;PLP, ROL
22340        .BYTE $3C ;ROR, RTI
22350        .BYTE $C0 ;RTS, SBC
22360        .BYTE $CC ;SEC, SED
22370        .BYTE $C1 ;SEI, STA
22380        .BYTE $57 ;STX, STY
22390        .BYTE $CC ;TAX, TAY
22400        .BYTE $CC ;TSX, TXA
22410        .BYTE $CC ;TXS, TYA
22420 ;
22430 L1028  .BYTE SET0,INSTLN
22440        .BYTE INC0
22450        .BYTE SKIP ;SKIP SPACES
22460        .BYTE EXPR,LINOUT-*
22470        .BYTE CHK0+SPC,L1036-*
22480        .BYTE $FE ;JMP TO L08E6
22490 L1036  .BYTE COPY,$02,$00
22500        .BYTE SKIP ;SKIP SPACES
22510        .BYTE RLBL,L103D-*
22520 L103D  .BYTE LVAL,L104C-*,L104C-*,L104C-*
22530        .BYTE COPY,NUMVAL,LABVAL
22540        .BYTE BMOV,CONST2,CNST7E,$0C
22550        .BYTE GERR,DRTYPE,L104C-*
22560 L104C  .BYTE $FF ;JMP TO LINOUT
22570 L104E  .BYTE EX65
22580        STX DRTYPE+1
22590        LDX #$03 
22600 L1051  LDA LABL40+1
22610        CMP DIRHI,X
22620        BEQ L1062
22630 L105D  DEX 
22640        BPL L1051
22650        JSR L11DC ;EXECUTE P-CODE
22660        .DBYTE L114F+OFFSET
22670 DIRHI  .BYTE ADDZ,TXTPOS,$92,$19
22680 L10A7  .BYTE SET0,INSTLN
22690 ;OUTPUT LINE OF ASSEMBLED CODE THEN
22700 ;MOVE ON TO NEXT LINE
22710 LINOUT .BYTE OUTP ;OUTPUT ASSEMBLED LINE
22720 ;GET NEXT LINE AND GO TO L10B0 IF END
22730 L10AB  .BYTE NXLN,L10B0-*
22740        .DBYTE L085D+OFFSET ;PROCESS NEXT LINE
22750 L1062  STX DRTYPE
22760        CPX #3
22770        BNE STDRLN
22780        DEX 
22790 STDRLN STX INSTLN
22800        JSR L11DC ;EXECUTE P-CODE
22810        .BYTE SKIP ;SKIP SPACES
22820 ;IF .BYT, .WOR, OR .DBY, GO TO L1230
22830        .BYTE BNEQ,DRTYPE,CONST0,L1230-*
22840        .BYTE OUTP
22850 ;END OF SOURCE FILE REACHED
22860 L10B0  .BYTE BNEQ,ASMOPT,CONST2,L0E8A-*
22870 ;IF DOING 'A2', FLUSH BUFFER
22880        .BYTE SET1,ASMBRK
22890        .BYTE OUTP
22900 L0E8A  .BYTE INCR,PASS ;NEXT PASS
22910 ;GO BACK TO NXTPAS TO START NEXT PASS
22920        .BYTE BRGR,PASS,CONST2,L0E94-*
22930        .DBYTE NXTPAS+OFFSET
22940 L0E94  .BYTE $FD ;JMP TO L0620
22950 L123B  .BYTE BEQU,DRTYPE,CONST1,L1244-*
22960 L1241  .BYTE $FE ;JMP TO L08E6
22970 L1246  .BYTE CHK0+$0D,L1098-*
22980        .BYTE MOVB,$72
22990        .BYTE OUTP
23000 L1244  .BYTE INC0
23010        .BYTE CHK0+$27,L1251-* ;SINGLE QUOTE CHAR
23020        .DBYTE L1246+OFFSET
23030 L1251  .BYTE INC0
23040        .BYTE CHK0+$27,L1246-* ;SINGLE QUOTE CHAR
23050 L1098  .DBYTE L108E+OFFSET
23060 L109A  .BYTE INC0
23070 ;PROCESS .BYTE, .WORD OR .DBYTE
23080 L1230  .BYTE CHK0+$27,L123B-* ;SINGLE QUOTE
23090        .BYTE EXPR,L1241-*
23100        .BYTE COPY,NUMVAL,INSTRN
23110        .BYTE BNEQ,DRTYPE,CONST3,L108A-*
23120        .BYTE EX65
23130        LDA INSTRN
23140        LDY INSTRN+1
23150        STA INSTRN+1
23160        STY INSTRN
23170        JSR L11DC ;EXECUTE P-CODE
23180 L108A  .BYTE OUTP
23190 L108E  .BYTE CHK0+',,L109A-*
23200        .BYTE CHK0+SPC,L10AB-*
23210 ;ERROR 7 - INVALID EXPRESSION
23220        .BYTE RERR,$07
23230        .BYTE $FF ;JMP TO LINOUT
23240 ;
23250 ;ZERO PAGE LOCATIONS TO BE UPDATED UPON STARTUP
23260 ZPADDR .BYTE $02,IP,IP+1,$2E
23270        .BYTE $2F,CNST14,$3A,CNST10
23280        .BYTE CONST1,CONST3,NOPBYT,NOPBYT+1
23290        .BYTE CNST80,$5B,$5D,$5E
23300        .BYTE $60,$62,$65,$67
23310        .BYTE CNST50,CONST2,CNST12,CNST7E
23320        .BYTE CNST6C,CNST44,CONST4,$EE
23330        .BYTE CONST5,CONST6,$00,$80
23340        .BYTE ASMOFS,ASMOFS+1,STTEXT,STTEXT+1
23350        .BYTE ENDMEM,ENDMEM+1,ENDTXT,ENDTXT+1
23360 ;
23370 ;VALUES TO BE PUT IN THESE MEMORY LOCATIONS
23380 ZPCONT .BYTE $80
23390        .WORD PINIT
23400        .BYTE $FF
23410        .BYTE $FF,LINENO,$36,10
23420        .BYTE 1,3,$EA,$EA ;$EA IS A NOP INSTRUCTIO
23430        .BYTE $80,$B0,$40,$20
23440        .BYTE $40,$10,$0C,$03
23450        .BYTE INSTRN,2,12,LABVAL
23460        .BYTE LABL40,ASMADR,4,$37
23470        .BYTE 5,6,$80,$0D
23480 ;LAST 8 BYTES OF ASSEMBLER CODE:
23490 ;2 BYTES OFFSET FOR A3 ASSEMBLE TO MEMORY
23500 ;2 BYTES START OF AVAILABLE MEMORY
23510 ;2 BYTES END OF AVAILABLE MEMORY
23520 ;2 BYTES END OF ASSEMBLER SOURCE TEXT
23530        .WORD 0,LOMEM,HIMEM
23540 ENDIMG .WORD LOMEM
23550 LOMEM  ;BOTTOM OF AVAILABLE MEMORY