I've been experimenting with the NESStress ROM for awhile but am a bit curious about this test:
"PPU First Read Then Write. - This tests if the PPU address is increased after a first read."
The code can be found below. Is the PPU Address increased even on dummy-reads (the first $2007 read below) or am I getting it wrong? If I implement this behaviour in my emu, I get very strange results (or if I have done something else wrong.. ).
"PPU First Read Then Write. - This tests if the PPU address is increased after a first read."
The code can be found below. Is the PPU Address increased even on dummy-reads (the first $2007 read below) or am I getting it wrong? If I implement this behaviour in my emu, I get very strange results (or if I have done something else wrong.. ).
Code:
.PPUTest2
lda #$20
sta $2006
lda #$60
sta $2006
lda $2007 ;Increments PPU address even if it's a dummy?
ldx #$30
.PPUWriteLoop2
stx $2007 ;Writing starts at $2061
inx
cpx #$3a
bne .PPUWriteLoop2
lda #$20
sta $2006
lda #$61
sta $2006
lda #$20
sta $2006
lda #$60
sta $2006
lda $2007 ;Increments PPU address even if it's a dummy?
ldx #$30
.PPUWriteLoop2
stx $2007 ;Writing starts at $2061
inx
cpx #$3a
bne .PPUWriteLoop2
lda #$20
sta $2006
lda #$61
sta $2006