Search found 102 matches

by Alyosha_TAS
Mon Aug 14, 2017 4:58 pm
Forum: NESemdev
Topic: Rambo-1 Test ROMs
Replies: 3
Views: 3740

Rambo-1 Test ROMs

Ok, so in order to split this from Zepper's RockNES thread I am making this one to discuss what tests need to be run to characterize Rambo-1 IRQs. I've already started on the test ROM infrastructure, so I want to get an idea what the first test is that should be run. so far I have this to start from...
by Alyosha_TAS
Mon Aug 14, 2017 1:52 pm
Forum: GBDev
Topic: When is the STAT IRQ line de-asserted?
Replies: 1
Views: 1819

When is the STAT IRQ line de-asserted?

I am starting to work on interrupts in my emulator, but I don't quite follow exactly what's happening. So, let me pose an example. Let's say I have STAT IRQs enabled and both LY=LYC IRQs and mode 0 IRQs enabled, but, interrupts are disabled on the CPU side (with the DI instruction.) Let's say I enab...
by Alyosha_TAS
Mon Aug 14, 2017 1:29 pm
Forum: GBDev
Topic: When does DEC set the half carry flag?
Replies: 7
Views: 4128

Re: When does DEC set the half carry flag?

Thanks for the replies. Maybe GB CPU documentation could use a revision, since both sources I found that indicated what happens with the half carry flag say the opposite of what should actually happen.
by Alyosha_TAS
Mon Aug 14, 2017 1:26 pm
Forum: NESemdev
Topic: Spot bug in Mesen and Nintaco
Replies: 20
Views: 18376

Re: Spot bug in Mesen and Nintaco

1: Game reads input port, checks for changes from previous state. 2: Emulator updates emulated gamepad state. 3: Game reads input port again to set previous state variables. With various lengths of time passing between the steps. If the game polls the controller ports twice within the same frame an...
by Alyosha_TAS
Sat Aug 12, 2017 4:35 pm
Forum: GBDev
Topic: When does DEC set the half carry flag?
Replies: 7
Views: 4128

Re: When does DEC set the half carry flag?

So it's just wrong documentation then? Are there any other pitfalls I should watch out for with that guide? EDIT: Given that the gameboy cpu is based off of the z80, I looked at the z80 insrtuction and indeed: H is set if borrow from bit 4, otherwise, it is reset. I guess it would be strange if this...
by Alyosha_TAS
Sat Aug 12, 2017 3:38 pm
Forum: GBDev
Topic: When does DEC set the half carry flag?
Replies: 7
Views: 4128

When does DEC set the half carry flag?

Hi, I am working on a GB emulator, but I am getting stuck trying to understand the half carry flag. In the CPU manual here: http://marc.rawer.de/Gameboy/Docs/GBCPUman.pdf for the DEC instruction on page 89 it says that: H - Set if no borrow from bit 4. I understand this to mean that the half carry f...
by Alyosha_TAS
Sat Aug 12, 2017 12:50 pm
Forum: NESemdev
Topic: RockNES - NES emulator for Windows [5.54] 09/23/2017
Replies: 77
Views: 39316

Re: RockNES - NES emulator for Windows [5.53] 08/08/2017

Not terribly rare—I believe I could just pick one up at the local retrogaming store for something around $10 to $20—but I don't have the patience to figure out how to make the test cases to establish what's going on. The most I'd be willing to offer is making a flashcart and sharing logic analyzer ...
by Alyosha_TAS
Sat Aug 12, 2017 6:09 am
Forum: NESemdev
Topic: RockNES - NES emulator for Windows [5.54] 09/23/2017
Replies: 77
Views: 39316

Re: RockNES - NES emulator for Windows [5.53] 08/08/2017

The panel colors are different. There's some yellow-ish on it. Other than that, well, no surprises until then. Both games work with no glitches, but is the exact same board? As I said, Klax requires +1, but HD doesn't. How rare are these carts? I'd be willing to pitch in some money towards getting ...
by Alyosha_TAS
Wed Aug 09, 2017 7:48 am
Forum: SNESdev
Topic: Introducing the VeriSNES (FPGA-based SNES)
Replies: 307
Views: 155950

Re: Introducing the VeriSNES (FPGA-based SNES)

On a seperate note, I read over the funding discussion and I have to say I am a bit concerned. You basically want to sell information (which is fine), but without any independent assessment or peer review, how can we know how good the information is? In my opinion, the value of information is based ...
by Alyosha_TAS
Wed Aug 09, 2017 6:37 am
Forum: SNESdev
Topic: Introducing the VeriSNES (FPGA-based SNES)
Replies: 307
Views: 155950

Re: Introducing the VeriSNES (FPGA-based SNES)

Really cool! I've followed this project for a bit and am happy to see it nearing completion (or at least initial release status.) I have a couple of questions about things you mentioned earlier. Is the Bad Apple demo issue (that is still listed as a request in the opening post) still present? I saw ...
by Alyosha_TAS
Mon Aug 07, 2017 3:04 pm
Forum: NESemdev
Topic: visual timing tests for hblank / sprite 0 hit
Replies: 8
Views: 3537

Re: visual timing tests for hblank / sprite 0 hit

Well, really the test should be measured in pixels not CPU cycles. The point of my using CPU cycles was to estimate how much range software has for getting this correct. A rig for testing how many cycles you can push your code back or forth until it will break. If you're trying to tune an emulator,...
by Alyosha_TAS
Sun Aug 06, 2017 8:45 am
Forum: NESemdev
Topic: visual timing tests for hblank / sprite 0 hit
Replies: 8
Views: 3537

Re: visual timing tests for hblank / sprite 0 hit

Oh cool another test using the black / white flag. It would be good to nail down the exact behaviour here. I really don't see any way the nmi_sync test can work without some kind of delay involved with this flag, whether in latching the write or in applying the correction somewhere later in the rend...
by Alyosha_TAS
Sun Aug 06, 2017 8:43 am
Forum: NESemdev
Topic: Strike Wolf (MGC-014) (Unl) [!] zapper
Replies: 3
Views: 2323

Re: Strike Wolf (MGC-014) (Unl) [!] zapper

It mostly works in BizHawk (accuracy is a little low but generally correct.)
you have to plug the zapper in port 2.

WARNING: I don't recommend it though, it started hurting my eyes only after like 1 minute of playing. The flashing is quite a bit worse then in other zapper games.
by Alyosha_TAS
Thu Aug 03, 2017 9:07 am
Forum: NESemdev
Topic: RockNES - NES emulator for Windows [5.54] 09/23/2017
Replies: 77
Views: 39316

Re: RockNES - NES emulator for Windows [5.52] 07/14/2017

Have you checked all of the glitch candidates I posted here ? When you use always latch +0 or always latch +1, you'll either get the garbage line above the status bar (visible only once you scroll down in the introductory level), or corrupted "continue" lettering in the item screen. I think at this...
by Alyosha_TAS
Wed Aug 02, 2017 6:54 pm
Forum: NESemdev
Topic: RockNES - NES emulator for Windows [5.54] 09/23/2017
Replies: 77
Views: 39316

Re: RockNES - NES emulator for Windows [5.52] 07/14/2017

Attached find a Nintendulator source file that runs both Skull & Crossbones , Hard Drivin' , Rolling Thunder (U.S. version) and Xybots like in the various videos I posted. Basically, I am making two assumptions that are not described in the wiki: It's not IRQcounter=IRQlatch +1, but IRQcounter=IRQl...