dos33fsprogs/demos/demosplash2022/ay3_write_regs.s
2022-11-12 18:40:59 -05:00

33 lines
949 B
ArmAsm

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; ay3 write regs
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; write all 14 registers at AY_REGS
ay3_write_regs:
; bytes
ldx #13 ; 2
ay3_write_reg_loop:
lda #MOCK_AY_LATCH_ADDR ; latch_address for PB1 ; 2
ldy #MOCK_AY_INACTIVE ; go inactive ; 2
stx MOCK_6522_ORA1 ; put address on PA1 ; 3
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 3
sty MOCK_6522_ORB1 ; 3
; value
lda AY_REGS,X ; 2
sta MOCK_6522_ORA1 ; put value on PA1 ; 3
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB1 ; write on PB1 ; 3
sty MOCK_6522_ORB1 ; 3
dex ; 1
bpl ay3_write_reg_loop ; 2
; rts