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112 lines
3.4 KiB
Plaintext
112 lines
3.4 KiB
Plaintext
;Apple 1 program initialization code for c02 programs
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SUBROUTINE _APPLE1
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;System Specific ASCII Key Mappings
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DELKEY EQU $5F ;Delete/Backspace Key (Left Arrow/Underscore)
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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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;Locations used by Monitor
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.XAML EQU $24 ;Examine Index
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.XAMH EQU $25 ;
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.STL EQU $26 ;Store Index
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.STH EQU $27 ;
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.HEXL EQU $28 ;Hex Data
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.HEXH EQU $29 ;
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.YSAVE EQU $2A ;Y Register Storage
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.MODE EQU $2B ;Mode: Store, Examine, Block Examine
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.IN EQU $200 ;Input Buffer
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;Standard Library Variables
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SRCPTR EQU $30 ;Source String Pointer (stdio.a02)
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SRCLO EQU $30 ;Source String Pointer (stdio.a02)
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SRCHI EQU $31
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DSTPTR EQU $32 ;Destination String Pointer (string.a02)
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DSTLO EQU $32 ;Destination String Pointer (string.a02)
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DSTHI EQU $33
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BFRLO EQU $34 ;Work Buffer Pointer
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BFRHI EQU $35
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BLKLO EQU $36 ;Block Segment Pointer (block.a02)
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BLKHI EQU $37
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STKLO EQU $38 ;System Pointer (pointer.a02)
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STKHI EQU $39
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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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BLKLEN EQU $47 ;Block Segment Length
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BLKSLO EQU $48 ;Block Start Address
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BLKSHI EQU $49
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BLKELO EQU $4A ;Block End Address
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BLKEHI EQU $4B
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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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SYSBFP EQU $50 ;Position in System Buffer
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SYSBFL EQU 128 ;System Buffer Size (128 Bytes)
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SYSBFR EQU .IN ;System Buffer (Input Buffer
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;PIA 6820 Registers
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.KBD EQU $D010 ;Keyboard Data
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.KBDCR EQU $D011 ;Keyboard Control Register
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.DSP EQU $D012 ;Display Data
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.DSPCR EQU $D013 ;Display Control Register
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EXIT EQU $FF00 ;Monitor Entry Point
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.ECHO EQU $FFEF ;Subroutine - Print Character in Accumulator
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PRBYTE EQU $FFDC ;Subroutine - Print Accumulator as Hexadadecimal number
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PRHEX EQU $FFE5 ;Subroutine - Print Low Nybble of Accumulator as Hex Digit
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ORG $0300 ;Start one page above Monitor input buffer
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START: LDX #$FF ;Reset stack - the monitor doesn't do this
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TXS ; (probably because of lack of space)
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JSR NEWLIN ;Move cursor to next line before executing program
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JMP MAIN ;Execute Program
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;Subroutine Poll Keyboard
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PLKEY: INC RDSEED ;Cycle Keypress Counter
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LDA #0 ;Set Return Value to 0
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BIT .KBDCR ;Check the Keyboard Control Register
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BPL .PLKEYX ;If No Key Pressed, Return 0
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LDA .KBD ;Else Read Key and Return
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.PLKEYX RTS
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GETKEY: JSR PLKEY ;Read Keyboard
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AND #$7F ;Strip High Bit
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RTS
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BIT .GETKEM ;If Character is in
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BEQ .GETKEX ; Alpha Block ($40-$74)
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AND #$5F ; Strip Bit 5
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.GETKEX RTS
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.GETKEM DC $40 ;Character Block Bit Mask
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GETCHR: JSR GETKEY ;Get Keypress
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BEQ GETCHR ;Loop if No Key Pressed
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RTS
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PUTCHR EQU .ECHO ;Alias to Monitor Routine
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;Delete Previous Character
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DELCHR: LDA #DELKEY ;Load Underscore Character
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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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JMP PUTCHR ; and Print it
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INCLUDE "../include/putstr.a02" ;PUTSTR routine
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ENDSUBROUTINE
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