Search found 238 matches

by Fiskbit
Fri Jan 11, 2019 12:06 am
Forum: NESdev
Topic: Graphical glitches on the Everdrive
Replies: 49
Views: 46604

Re: Graphical glitches on the Everdrive

I ran thefox's oam-decay-test.nes on my Everdrive and found the results pretty interesting. If I provide no input at all (so rendering is enabled, but OAM is not being rewritten each vblank), I lose 2 sprite tiles (tiles 48 and 56), usually at the same time, after about half a second, and then 4 mor...
by Fiskbit
Thu Jan 10, 2019 1:52 am
Forum: NESdev
Topic: Graphical glitches on the Everdrive
Replies: 49
Views: 46604

Re: Graphical glitches on the Everdrive

Interesting. So, the wiki references this thread where thefox couldn't get OAM decay to occur on PAL, citing this as the source for having 20 safe scanlines (which was considered approximate). I don't know if that's also the source for the statements about refresh occurring everywhere but early vbla...
by Fiskbit
Wed Jan 09, 2019 11:04 pm
Forum: NESdev
Topic: Graphical glitches on the Everdrive
Replies: 49
Views: 46604

Re: Graphical glitches on the Everdrive

@Nicole/lignariq: Yeah, earlier hardware not supporting $2004 reads is an unfortunate limitation, for sure. lidnariq's sprite 0 trick is a neat workaround I hadn't thought of before. @Sour: The lag frame case I was talking about was specifically with sprite corruption I observed during lag frames wi...
by Fiskbit
Wed Jan 09, 2019 7:32 am
Forum: NESdev
Topic: Graphical glitches on the Everdrive
Replies: 49
Views: 46604

Re: Graphical glitches on the Everdrive

That's certainly a lot more visible! I'm actually planning to do some OAM decay testing in the near future; I'd like to get an idea of how long it takes before decay occurs and how it tends to decay. Beyond just understanding it better, I'm curious if it could have utility (could it reasonably be us...
by Fiskbit
Wed Jan 09, 2019 6:29 am
Forum: NESemdev
Topic: APU behavior (Eliminator Boat Duel)
Replies: 22
Views: 19422

Re: APU behavior (Eliminator Boat Duel)

Tried out your test on Everdrive. DmcPowerOnBuzz starts up with buzzing, pressing a button silences the buzzing, and it remains silent after a reset, so seems to confirm that address is preserved across resets. I did further testing with my sample-based test and it plays the full sample normally aft...
by Fiskbit
Tue Jan 08, 2019 2:32 pm
Forum: NESdev
Topic: Graphical glitches on the Everdrive
Replies: 49
Views: 46604

Re: Graphical glitches on the Everdrive

Someone I know used to have an issue with Everdrive where sprites would mess up during lag frames in Zelda (IIRC, sprite RAM bits would get set). I believe this turned out to be a power supply issue, since the cart draws more power than is typical. During lag frames in Zelda, OAM DMA isn't performed...
by Fiskbit
Tue Jan 08, 2019 1:45 pm
Forum: NESemdev
Topic: APU behavior (Eliminator Boat Duel)
Replies: 22
Views: 19422

Re: APU behavior (Eliminator Boat Duel)

Based on Eugene's results, the sample address should be initialized to $C000 and length to 1 byte, which should cause a buzzing on the C000 test. Since he tested on Everdrive, like me, I'm not sure we can trust those results. I'll do additional testing on this tonight. The test for this should be s...
by Fiskbit
Tue Jan 08, 2019 4:18 am
Forum: NESemdev
Topic: APU behavior (Eliminator Boat Duel)
Replies: 22
Views: 19422

Re: APU behavior (Eliminator Boat Duel)

I did some testing with my own test ROMs on Everdrive and suspect that its firmware writes to these registers (unless I was doing something wrong, setting the address in one ROM and switching to another did not seem to preserve it), so I can't say much about the power-on values, but it does appear t...
by Fiskbit
Sat Jan 05, 2019 9:38 pm
Forum: NESdev
Topic: Glitch-free controller reads with DMC?
Replies: 64
Views: 67630

Re: Glitch-free controller reads with DMC?

By testing this on real hardware via Everdrive, I believe I've been able to confirm this write behavior, and also discovered that the only emulator that seems to be getting this totally correct right now is Nintendulator 0.980. Testing this is a bit tricky because it seems that you can have timing a...
by Fiskbit
Sat Jan 05, 2019 4:50 am
Forum: NESdev
Topic: Glitch-free controller reads with DMC?
Replies: 64
Views: 67630

Re: Glitch-free controller reads with DMC?

I tried to write a test that involved watching for corruption while doing repeated synced joypad reads, with the goal of identifying whether the emulator supported this method of reading. Surprisingly, despite being synced, I was encountering corruption when testing on Mesen. What I learned was that...
by Fiskbit
Fri Jan 04, 2019 6:12 am
Forum: NESdev
Topic: Demo. Fzero like game on NES.
Replies: 43
Views: 17810

Re: Demo. Fzero like game on NES.

I think this looks really cool, and even as-is, I'd probably rather play a racing game like this than Rad Racer. It may not be the prettiest, but the gameplay could be worth it.

Nice work, and I'd love to see improvements on this.
by Fiskbit
Tue Jan 01, 2019 9:28 pm
Forum: NESemdev
Topic: 2nd2006_next_level test rom and extensions
Replies: 55
Views: 54103

Re: 2nd2006_next_level test rom and extensions

This post by blargg indicates there is a way to detect the alignment and that he may have made a test ROM for it, though I haven't yet found evidence of such a ROM being posted. The data also shows that alignments may have different likelihoods, though I'd like to see more testing done on that to b...
by Fiskbit
Tue Jan 01, 2019 6:38 pm
Forum: NESemdev
Topic: 2nd2006_next_level test rom and extensions
Replies: 55
Views: 54103

Re: 2nd2006_next_level test rom and extensions

I've tested how often I get each result across batches of 30 resets. I only tracked number for the first several tests, and then started tracking order, as well. I also did tests on how often I get jitter when starting up split_scroll_test_v2. Here are my results in the order I got them: (y = yes gl...
by Fiskbit
Tue Jan 01, 2019 5:32 am
Forum: NESemdev
Topic: 2nd2006_next_level test rom and extensions
Replies: 55
Views: 54103

Re: 2nd2006_next_level test rom and extensions

I finally got all the equipment I need to run some tests on my NTSC frontloader via Everdrive. Here are some results. ppu_2005_glitch.nes & ppu_2406_glitch.nes After many resets, I can confirm that the $2005 and $2406 tests do indeed show the glitching that lidnariq predicted for some (but not all) ...
by Fiskbit
Fri Dec 28, 2018 12:50 pm
Forum: NESdev
Topic: Breakpoint confusion (read, write, execute, and other...)
Replies: 5
Views: 3392

Re: Breakpoint confusion (read, write, execute, and other...

If you want to know when an address is read by some code, use a read breakpoint. If you want to know when it's written to by some code, set a write breakpoint. If you want to know when it's executed as code by the CPU, set an execute breakpoint. If you really don't know, then use all 3; they're not ...