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https://github.com/RevCurtisP/C02.git
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47 lines
1.5 KiB
NASM
47 lines
1.5 KiB
NASM
;Apple 1 program initialization code for c02 programs
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;Locations used by Operating System
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PROMPT EQU $33 ;ASCII character for INPUT prompt symbol
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LOMEM EQU $4A ;
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HIMEM EQU $4C
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BASIC EQU $67 ;Start of BASIC program
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VARBLS EQU $69 ;End of BASIC program and start of variable space
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ARRAYS EQU $6B ;Start of defined array space
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ARRAYE EQU $6D ;End of defined array space
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STRNGS EQU $6F ;Start of string storag
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;Locations used by Hi-Res Graphics
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HPLOTX $E0 ;X of last HPLOT
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HPLOTY $E2 ;Y of last HPLOT
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HCOLOR $E4 ;
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HIRES $E6 ;
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SCALE $E7 ;
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SHAPES $E8 ;Shape table start address
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XDRAWS $EA
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CSPEED $F1
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ROTATE $F9
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TIMEDM EQU $BF90 ;Day/month
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TIMEYR EQU $BF91 ;Year
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TIMEMN EQU $BF92 ;Minute
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TIMEHR EQU $BF93 ;Hour
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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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JMP MAIN ;Execute Program
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RDKEY: BIT KBDCR ;Check the Keyboard Control Register
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BPL RDKEY ; and loop if key not pressed
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LDA KBD ; Read key into Accumulator
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RTS
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