Does this ever actually happen?
Dwedit wrote:
Does this ever actually happen?
I actually tried this using my PowerPak (before I sent it back for fixing) and obviously it works but it seems to be required to do this every frame since the sprites disappear otherwise.
This is a behaviour that doesn't seem to be handled by most emulators(?) by the way...
If only a few sprites should be updated, this would be the way to go since it doesn't take 513(?) cycles as sprite-DMA does.
Are you sure about the disappearing sprites?
Metal Max does not update the OAM while the dialog windows are visible.
Metal Max does not update the OAM while the dialog windows are visible.
Dwedit wrote:
Are you sure about the disappearing sprites?
Metal Max does not update the OAM while the dialog windows are visible.
Metal Max does not update the OAM while the dialog windows are visible.
I only did a simple test where I copied the sprites only once using $2004 and I never saw any sprites on the screen at all. However the same ROM looks good in Nintendulator so I guess that behaviour isn't emulated.
Have the exact conditions/implications been determined for this phenomenon? I mean, would every NES in the world behave the same way? In that case, I guess it wouldn't be a major pain to implement this in an emulator..
By the way, is it there any comercial prog relying on such a phenomenon?
By the way, is it there any comercial prog relying on such a phenomenon?
As I understand it, OAM will start to decay only if you leave the rendering turned off for at least a frame.
As for timing, I see about 45 cycles per sprite:
So if you have more than about 11 sprites, DMA is faster, unless you really need a rock-solid real-time loop for $4011 audio playback.
As for timing, I see about 45 cycles per sprite:
Code:
:
lda $200,x
sta OAMDATA
inx
lda $200,x
sta OAMDATA
inx
lda $200,x
sta OAMDATA
inx
lda $200,x
sta OAMDATA
inx
dey
bne :-
lda $200,x
sta OAMDATA
inx
lda $200,x
sta OAMDATA
inx
lda $200,x
sta OAMDATA
inx
lda $200,x
sta OAMDATA
inx
dey
bne :-
So if you have more than about 11 sprites, DMA is faster, unless you really need a rock-solid real-time loop for $4011 audio playback.