My devcart appears (to me) to be indexing some wrong tiles every few frames. No more than 5 or 6 tiles are doing this at a time on screen, sometimes none are (depending on the game) and it appears to be only happening to sprites. I believe the tiles which do this are consistant at every reset. I am using SRAM so it's not an EPROM-related issue, I also don't think there is a latency issue. All I can think of is a dry address line but I don't think this is the case since when I pause games, sometimes the tile is stable even if it's the wrong one. Any ideas?
I've tried to make out which tiles are being replaced by which but it's not very easy to make out tiles on a TV. Here are some examples:
Edit: Aha! tile $45 becomes $C5, $55 becomes $D5 etc, this is an A13 issue... Wonder why this doesn't happen on the BG table and why it only happens on some sprites and only on some frames.
Edit #2: Ehrm, this appears to be a issue with the Famicom, I switched to a 1984 console and it's working fine... maybe the PPUs have different timings.
I've tried to make out which tiles are being replaced by which but it's not very easy to make out tiles on a TV. Here are some examples:
Edit: Aha! tile $45 becomes $C5, $55 becomes $D5 etc, this is an A13 issue... Wonder why this doesn't happen on the BG table and why it only happens on some sprites and only on some frames.
Edit #2: Ehrm, this appears to be a issue with the Famicom, I switched to a 1984 console and it's working fine... maybe the PPUs have different timings.