stella/test/roms/bankswitching/_code/F8.asm

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2020-04-03 15:08:42 +00:00
;;A bankswitching demo for the F8 BS technique. 2 4K banks (8K total)
;;By: Rick Skrbina
processor 6502
include "vcs.h"
include "macro.h"
seg.u vars
org $80
PF_Color ds 1
seg Bank_0
org $E000
rorg $F000
nop
nop
nop
Start_0
CLEAN_START
; jsr Call_1
lda #$FF
sta PF1
StartFrame
lda #2
sta VBLANK
sta VSYNC
sta WSYNC
sta WSYNC
sta WSYNC
lda #0
sta VSYNC
ldy #37
Vert
sta WSYNC
dey
bne Vert
lda #0
sta VBLANK
ldy #192
Pic
sta WSYNC
dey
bne Pic
lda #2
sta VBLANK
ldy #30
Over
sta WSYNC
dey
bne Over
jsr Call_1
lda PF_Color
sta COLUPF
jmp StartFrame
org $EFE0
rorg $FFE0
Call_1
stx $FFF9
nop
nop
nop
nop
nop
nop
rts
org $EFF8
rorg $FFF8
.word $FFFF
.word Start_0
.word Start_0
.word Start_0
seg Bank_1
org $F000
rorg $F000
Init_1
sta $FFF8
Bank1_Sub
; lda #$0F
; sta COLUPF
inc PF_Color
rts
org $FFE3
rorg $FFE3
jsr Bank1_Sub
stx $FFF8
org $FFF8
.word $FFFF
.word Init_1
.word Init_1
.word Init_1