mirror of
https://github.com/RevCurtisP/C02.git
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125 lines
3.4 KiB
Plaintext
125 lines
3.4 KiB
Plaintext
;py65mon program initialization code for c02 programs
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;System Specific ASCII Key Mappings
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DELKEY EQU $08 ;Delete/Backspace Key (Backspace)
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ESCKEY EQU $1B ;Escape/Stop Key (Escape)
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RTNKEY EQU $0D ;Return/Enter Key (Carriage Return)
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;Zero Page Locations
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SRCLO EQU $30 ;Source String Pointer (stdio.a02)
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SRCHI EQU $31
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DSTLO EQU $32 ;Destination String Pointer (string.a02)
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DSTHI EQU $33
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BLKLO EQU $34 ;Block Segment Pointer (block.a02)
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BLKHI EQU $35
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STKLO EQU $36 ;Stack Pointer (stack.a02)
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STKHI EQU $37
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RDSEED EQU $3E ;Pseudo-RANDOM Seed
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RANDOM EQU $3F ;Pseudo-RANDOM Number Storage
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TEMP0 EQU $40 ;Temporary Storage
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TEMP1 EQU $41
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TEMP2 EQU $42
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TEMP3 EQU $43
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BLKSLO EQU $46 ;Block Start Address
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BLKSHI EQU $47
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BLKELO EQU $48 ;Block End Address
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BLKEHI EQU $49
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BLKLEN EQU $4A ;Block Segment Length
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STKSLO EQU $4C ;Stack Start Address
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STKSHI EQU $4D
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STKELO EQU $4E ;Stack End Address
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STKEHI EQU $4F
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;Memory Mapped I/O
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PUTCON EQU $F001 ;Write Character to Console
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GETCON EQU $F004 ;Read Character from Console
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;Interrupt Vectors
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NMILO EQU $FFFA ;Non-Maskable Interrupt
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NMIHI EQU $FFFB
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RSTLO EQU $FFFC ;Reset
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RSTHI EQU $FFFD
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IRQLO EQU $FFFE ;Maskable Interrupt
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IRQHI EQU $FFFF
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ORG $0200 ;START Directly Above Stack
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START: JMP MAIN ;Execute Program
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;Poll Character from Keyboard
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POLKEY: INC RDSEED ;Cycle the RANDOM Seed (if not provided by system)
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LDA GETCON ;Read Character from Console
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CMP #$E0
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BEQ POLKEX ;If Not E0 Extended Key
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ORA #$00 ; Set Status Flags
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RTS ; and Return
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POLKEX: LDA GETCON ;Else Get Second Byte
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ORA #$80 ; Set High Byte
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RTS ; and Return
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;Read Character from Console
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GETKEY ;Same As RDKEY
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;Wait for Character from Console
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GETCHR: JSR POLKEY ;Read Character from Console
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BEQ GETCHR ; Loop if None Received
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RTS
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;Delete Previous Character
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DELCHR: LDA #$08 ;Load Backspace into Accumulator
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JSR PUTCHR ; and Print it
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LDA #$20 ;Load Space into Accumulater
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JSR PUTCHR ; and Print it
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LDA #$08 ;Load Backspace into Accumulator
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JMP PUTCHR ; and Print it
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;Advance Character to Next line
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NEWLIN: LDA #$0D ;Load C/R into Accumulator
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JSR PUTCHR ; and Print it
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LDA #$0A ;Load L/F into Accumulater
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; and fall into PRCHR
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;Print Character to Console
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PUTCHR STA PUTCON ;Write Character to Console
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RTS
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EXIT: BRK ;Return to Monitor
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;Print Byte as Two-Digit Hex Number to Console
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PRBYTE: PHA ;Save Accumulater
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LSR ;Shift Hi Nybble to Low Nybble
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LSR
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LSR
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LSR
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JSR PRHEX ; and Print it
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PLA ;Restore Accumulator
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; and fall into PRHEX
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;Print Low Nybble as Hex Digit to Console
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PRHEX: AND #$0F ;Strip High Nybb
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SED ;Set Decimal Flag for
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CLC ; Addition Wizardry
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ADC #$90 ;Convert to $90-$99,$00-$05
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ADC #$40 ;Convert to $30-$39,$41-$46
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CLD ;Clear Decimal Flag
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JMP PUTCHR ;Print Hex Digit and Return
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;Set Non-Maskable Interrupt Handler
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SETNMI: STY NMIHI
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STX NMILO
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RTS
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;Set Reset Handler
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SETRST: STY RSTHI
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STX RSTLO
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RTS
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;Set Maskable Interrupt Handler
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SETIRQ: STY IRQHI
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STX IRQLO
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RTS
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