mirror of https://github.com/RevCurtisP/C02.git
96 lines
2.4 KiB
Plaintext
96 lines
2.4 KiB
Plaintext
; Program initialization code for C02 programs
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; Template for System Specific Code
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ORG $0400 ;Program Start Address
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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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NULKEY EQU $00 ;No Key was Pressed (Null)
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;Zero Page Locations
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SRCPTR EQU $10
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DSTPTR EQU $12
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BFRLO EQU $14 ;Work Buffer Pointer
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BFRHI EQU $15
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STKSAV EQU $1D ;Stack Pointer Storage
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RDSEED EQU $1E ;Pseudo-RANDOM Seed
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RANDOM EQU $1F ;Pseudo-RANDOM Number Storage
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TEMP0 EQU $20 ;Temporary Storage
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TEMP1 EQU $21
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TEMP2 EQU $22
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TEMP3 EQU $22
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BLKBGN EQU $30 ;Block Start Address
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BLKEND EQU $32 ;Block End Address
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BLKPTR EQU $34 ;Block Pointer
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BLKLEN EQU $36 ;Block Segment Length
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STKSLO EQU $48 ;Stack Start Address
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STKSHI EQU $49
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STKELO EQU $4A ;Stack End Address
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STKEHI EQU $4B
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STKLO EQU $4C ;Stack Pointer
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STKHI EQU $4D
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;Memory Mapped I/O
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IOBASE EQU $E000
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IOINIT EQU IOBASE+0 ;Clear Terminal Window
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IOPUTC EQU IOBASE+1 ;Put Character
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IOPUTR EQU IOBASE+2 ;Put Raw Character
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IOPUTH EQU IOBASE+3 ;Put as Hexadecimal Number
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IOGETC EQU IOBASE+4 ;Get Character
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IOPOSX EQU IOBASE+5 ;Set Cursor X Position
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IOPOSY EQU IOBASE+6 ;Set Cursor Y Position
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START: LDX #$FF ;Initialize Stack Pointer
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TXS ;
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STX IOINIT ;Clear Screen
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JMP MAIN ;Execute Program
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;Exit Program and Return to Monitor
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EXIT: BRK ;Halt Debugger
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;Read Character from Console
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GETKEY EQU $FFE0 ;Emulator CHRIN Routine
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;Poll Character from Keyboard
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POLKEY: INC RDSEED ;Cycle the Random Seed
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LDA IOGETC ;Code Read from Keyboard
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RTS
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;Wait for Character from Console
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GETCHR: JSR POLKEY ;Usually calls PLKEY
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BEQ GETCHR ; until a non-zero is returned
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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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JMP PUTCHR ; and Print it
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;Advance Character to Next line
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NEWLIN: LDA #$0D ;Load Carriage Return
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JSR PUTCHR ;And Print It
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LDA #$0A ;Load Line Feed
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;Print Character to Console
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PUTCHR: STA IOPUTC ;Write Character to Screen
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RTS
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;Print Hexadecimal Digit
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PRHEX: AND #$0F
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ORA #'0'
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BNE PUTCHR
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;Print Hexadecimal Byte
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PRBYTE: STA IOPUTH ;Put as Hexadecimal Number
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RTS
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INCLUDE "putstr.a02" ;PUTSTR routine
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