99 lines
2.1 KiB
Plaintext
99 lines
2.1 KiB
Plaintext
processor 6502
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include "vcs.h"
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include "macro.h"
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include "xmacro.h"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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seg.u Variables
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org $80
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Temp .byte
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Macro that implements Bank Switching trampoline
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; X = bank number
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; A = hi byte of destination PC
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; Y = lo byte of destination PC
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MAC BANK_SWITCH_TRAMPOLINE
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pha ; push hi byte
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tya ; Y -> A
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pha ; push lo byte
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lda $1FF8,x ; do the bank switch
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rts ; return to target
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ENDM
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; Macro that performs bank switch
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MAC BANK_SWITCH
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.Bank SET {1}
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.Addr SET {2}
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lda #>(.Addr-1)
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ldy #<(.Addr-1)
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ldx #.Bank
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jmp BankSwitch
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ENDM
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seg Code
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; BANK 0
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org $1000
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rorg $F000
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;----The following code is the same on both banks----
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Start
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; Ensure that bank 0 is selected
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lda #>(Reset_0-1)
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ldy #<(Reset_0-1)
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ldx #0
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BankSwitch
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BANK_SWITCH_TRAMPOLINE
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;----End of bank-identical code----
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Reset_0
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CLEAN_START
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lda #$30
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sta COLUBK ; make the screen red
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bit INPT4 ; test button
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bmi Reset_0 ; button not pressed, repeat
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; Switch to Bank 2 routine
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lda #>(Main_1-1)
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ldy #<(Main_1-1)
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ldx #1
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jmp BankSwitch
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; Bank 0 epilogue
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org $1FFA
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rorg $FFFA
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.word Start ; NMI
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.word Start ; RESET
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.word Start ; BRK
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; BANK 1
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org $2000
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rorg $F000
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;----The following code is the same on both banks----
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Start
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; Ensure that bank 0 is selected
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lda #>(Reset_0-1)
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ldy #<(Reset_0-1)
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ldx #0
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BankSwitch
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BANK_SWITCH_TRAMPOLINE
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;----End of bank-identical code----
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Main_1
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inc Temp
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lda Temp
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sta COLUBK ; make rainbows
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bit INPT4 ; test button
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bpl Main_1 ; button is pressed, repeat
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BANK_SWITCH 0,Reset_0
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; Bank 1 epilogue
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org $2FFA
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rorg $FFFA
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.word Start ; NMI
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.word Start ; RESET
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.word Start ; BRK
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