Search found 119 matches

by Fiskbit
Sun Jul 05, 2020 7:43 pm
Forum: NES Hardware and Flash Equipment
Topic: Standardizing symbols for PCB mirroring pads
Replies: 18
Views: 339

Re: Standardizing symbols for PCB mirroring pads

krzysiobal's latest suggestion is pretty good. Alternatively, if the main issue here is just that mirroring and alignment are ambiguous on H and V solder pads, I feel it's pretty simply and concisely solved by just writing HA and VA.
by Fiskbit
Sun Jul 05, 2020 1:53 am
Forum: NES Hardware and Flash Equipment
Topic: Standardizing symbols for PCB mirroring pads
Replies: 18
Views: 339

Re: Standardizing symbols for PCB mirroring pads

Code: Select all

A B   A A   A A   A B
A B   B B   A A   C D
I don't want to have to think about what pictures mean. Yes, using letters is imperfect for single-screen, but it still clearly explains the idea and also matches our own wiki's representation.
by Fiskbit
Sun Jun 28, 2020 4:21 pm
Forum: NESdev
Topic: Mesen Debugger - Feedback/Feature Requests? (2018 edition)
Replies: 205
Views: 99680

Re: Mesen Debugger - Feedback/Feature Requests? (2018 edition)

You can find oam_flicker_test.nes and oam_flicker_test_reenable.nes in this and the following post . Assuming the safe region is indeed safe, a problem with it is that it's only just barely large enough to fit the variance in timing if you use IRQs, so you have to be very precise. Micro Machines is ...
by Fiskbit
Sun Jun 28, 2020 2:56 pm
Forum: NESdev
Topic: Mesen Debugger - Feedback/Feature Requests? (2018 edition)
Replies: 205
Views: 99680

Re: Mesen Debugger - Feedback/Feature Requests? (2018 edition)

OAM corruption emulation in Mesen is known to be incomplete. We believe it's roughly accurate for the case where you turn rendering off mid-frame and turn it back on in vblank, but if you turn it off mid-frame somewhere around dots 65 to 256 and then you turn it back on mid-frame, there is additiona...
by Fiskbit
Tue Jun 02, 2020 4:26 am
Forum: NES Hardware and Flash Equipment
Topic: Recommendation for dev cart?
Replies: 10
Views: 747

Re: Recommendation for dev cart?

gaugau's right that testing on hardware is an important step in development. While some emulators these days are indeed very accurate, there are known NES hardware quirks that they do not emulate properly or at all because the details aren't fully known, the behavior is analog and cannot be accurate...
by Fiskbit
Sat May 30, 2020 12:02 am
Forum: Newbie Help Center
Topic: Converting project to asm6 from nesasm3 - large chunks of code being marked "unidentified"
Replies: 8
Views: 751

Re: Converting project to asm6 from nesasm3 - large chunks of code being marked "unidentified"

Assuming you mean "unidentified block", Mesen doesn't inherently know whether any given byte is code, data, or unused, so everything starts out as unidentified and is only marked as code or data when it is actually accessed. When an instruction is executed, Mesen will automatically mark everything a...
by Fiskbit
Mon May 25, 2020 11:26 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom Grey Screen (no games running)
Replies: 13
Views: 1569

Re: Famicom Grey Screen (no games running)

All 3 CPU-06 boards I've seen have RP2A03 and RP2C02D(-0), so I'd guess this is a letterless CPU. I have seen a board that had an E CPU and D-0 PPU, but that was on a CPU-08 board (which is surprising) and I suspect is a rare combination. I've been told that dropping a letterless CPU into later syst...
by Fiskbit
Sun May 24, 2020 4:42 pm
Forum: NESemdev
Topic: Isolated Warrior unemulated graphical glitches
Replies: 9
Views: 2895

Re: Isolated Warrior unemulated graphical glitches

TL;DR: Added 9 new tests in v2: 1. Tests 6-7 test DMC DMA behavior relative to OAM DMA and show that: - 1a. $4015-initiated DMC DMA adds 2 cycles if it lands on a $4014 write cycle. - 1b. 4-cycle blips either immediately precede or follow the DMC DMA with a 0-cycle gap. - 1c. 4-cycle blips add only ...
by Fiskbit
Sat May 23, 2020 5:58 am
Forum: NESdev
Topic: Expanding MMC1 from 256kb to 512kb
Replies: 4
Views: 1088

Re: Expanding MMC1 from 256kb to 512kb

Yeah, if you don't know why it's switching, set a breakpoint for writes to $A000-BFFF and see what's writing to it before you intentionally switch back to the old half. I used SXROM for the Zelda 1 / Metroid 1 combo randomizer and didn't have any particular issues with it outside of emulator & flash...
by Fiskbit
Fri May 15, 2020 6:13 pm
Forum: NESemdev
Topic: Isolated Warrior unemulated graphical glitches
Replies: 9
Views: 2895

Re: Isolated Warrior unemulated graphical glitches

I've written a new test to try to get a better handle on the timings here. This test uses greyscale to measure the timing of various cases related to $4015 writes. The greyscale region shows a white dot every 3 pixels to allow for easy counting of CPU cycles, though because of the 1-dot jitter of th...
by Fiskbit
Sat May 09, 2020 5:57 am
Forum: NESdev
Topic: Unemulated problem in Alien Syndrome (J)
Replies: 9
Views: 1804

Re: Unemulated problem in Alien Syndrome (J)

I've updated the above 2007 glitch attachment with a new version that contains a write version of the test (with improved CHR and palettes to see nametable changes) and improves the controls by allowing the joypads to be swapped using the A button so it can be fully controlled with one joypad. The t...
by Fiskbit
Fri May 08, 2020 3:37 am
Forum: NESdev
Topic: Unemulated problem in Alien Syndrome (J)
Replies: 9
Views: 1804

Re: Unemulated problem in Alien Syndrome (J)

I've written and attached a test that confirms this $2007 behavior for reads. Here's what I found: - The increments from $2007 accesses appear to be delayed 5 or 6 dots depending on the alignment, which seems like a lot. This means that to land on dot 257 to conflict with 'hori(v) = hori(t)', the ac...
by Fiskbit
Thu May 07, 2020 1:31 am
Forum: NESdev
Topic: Optimizing scroll changes after MMC3 IRQs
Replies: 34
Views: 3434

Re: Optimizing scroll changes after MMC3 IRQs

I was considering the APU IRQ, myself, but I think the variance in interrupt timing will cause it to drift relative to the screen position. This needs to fire every 4 scanlines, so that error can build up over time. Maybe you could alternate between APU IRQs and scanline IRQs to keep it synced while...
by Fiskbit
Tue May 05, 2020 5:24 pm
Forum: NESdev
Topic: IRQ nesting due to OAM DMA
Replies: 9
Views: 1300

Re: IRQ nesting due to OAM DMA

You can fix the $2000 write glitch by writing to $2000 if your current nametable x is 0 and $2100 if it's 1. This causes the bad scanline to come from the appropriate nametable, hiding the issue. You're correct, though, that you don't have to worry about this if you use horizontal mirroring.
by Fiskbit
Tue May 05, 2020 2:00 am
Forum: NESdev
Topic: ASM6F - Confused how to load a 16-bit pointer into RAM
Replies: 8
Views: 1127

Re: ASM6F - Confused how to load a 16-bit pointer into RAM

You know, i remember reading in a thread somewhere that you could force Absolute mode, why on Gods green earth you would ever do that is beyond me, tight timing tricks i suppose? Yep. This is a really easy way to inject one cycle of delay, which can't be done by adding another instruction because i...