Search found 10423 matches

by lidnariq
Sun Apr 11, 2021 11:19 am
Forum: SNESdev
Topic: About audio in rom bandwidth capabilities, and a external cpu...
Replies: 6
Views: 177

Re: About audio in rom bandwidth capabilities, and a external cpu...

During access to addresses $21xx, the B bus is a copy of the bottom 8 bits of the A bus. During DMA it's driven according to the DMA registers. The rest of the time, it does random weird things. I don't think it's ever undriven (although looking at the die shot would let us tell), but it seems to ge...
by lidnariq
Sat Apr 10, 2021 11:57 pm
Forum: NESdev
Topic: NES PAL version, wavy edges on graphics
Replies: 13
Views: 814

Re: NES PAL version, wavy edges on graphics

Unfortunately, I promise, it's a problem with just how the NES generates video. Certain TVs might deal better with edges between different brightnesses of grey, but vertical lines between colors will always have that appearance. NTSC NESes have a different artifact - the pattern happens every 3 scan...
by lidnariq
Sat Apr 10, 2021 9:11 pm
Forum: Other Retro Dev
Topic: Was the GBA's sound worse than the 8-bit NES's sound?
Replies: 6
Views: 283

Re: Was the GBA's sound worse than the 8-bit NES's sound?

The 8-bit depth is pretty relevant here. I don't think it's fair to say that it means "almost nothing"? While I was definitely being flip, my point was more that focusing on a single bit of difference in bit depth is why it's misleading. The GBA has the problem that its output DAC always resamples ...
by lidnariq
Sat Apr 10, 2021 1:45 pm
Forum: Other Retro Dev
Topic: Was the GBA's sound worse than the 8-bit NES's sound?
Replies: 6
Views: 283

Re: Was the GBA's sound worse than the 8-bit NES's sound?

So why is the NES with 7-bit samples and a 1.79 MHz CPU sound better than the GBA with a MUCH better CPU, and 8-bit samples, and if the GBA could sound better, is there a example without the "scratchy" sound of the GBA? Because bit depth means almost nothing. https://en.wikipedia.org/wiki/1-bit_DAC
by lidnariq
Fri Apr 09, 2021 5:02 pm
Forum: NESemdev
Topic: RockNES 5.66 -April 9th 2021-
Replies: 16
Views: 6498

Re: RockNES 5.66 -April 9th 2021-

2. You mean like use its mapper emulation to intercept $4016/$4017 access kind of like a Game Genie? Or patch the ROM on the fly? The Everdrive does have mapper 99 listed so maybe it does something hacky with these games. I have no idea if mapper 99 was listed years ago when I tried VS SMB though. ...
by lidnariq
Fri Apr 09, 2021 4:01 pm
Forum: NESemdev
Topic: RockNES 5.66 -April 9th 2021-
Replies: 16
Views: 6498

Re: RockNES 5.66 -April 9th 2021-

um... 1- Vs. SMB was only released for the 2C04-0004, so if you played it on a home console on a flashcart, the colors would all be Very Wrong. If you don't remember them being Very Wrong, you most likely played a version that was patched for home consoles. very-wrong-colors.png 2- The Everdrive can...
by lidnariq
Fri Apr 09, 2021 2:21 pm
Forum: NESemdev
Topic: RockNES 5.66 -April 9th 2021-
Replies: 16
Views: 6498

Re: RockNES 5.66 -April 9th 2021-

The Vs. System is not the same hardware as the NES, and you shouldn't have $4016 and $4017 behaves the same for both.

It is absolutely correct that if you put Vs. SMB on a NES cart it would perceive the coin drop as continuously activated.
by lidnariq
Thu Apr 08, 2021 8:32 pm
Forum: GBDev
Topic: GBDK2020 - Is it smart trying to outsmart the compiler ?
Replies: 8
Views: 394

Re: GBDK2020 - Is it smart trying to outsmart the compiler ?

If you don't know that the compiler is doing the slow thing, then it's definitely premature to try to "help" it.

This is true for all optimizations ever, honestly. If you don't know what's taking up time, your assumption will probably be wrong and will make things worse instead.
by lidnariq
Thu Apr 08, 2021 8:15 pm
Forum: GBDev
Topic: GBDK2020 - Is it smart trying to outsmart the compiler ?
Replies: 8
Views: 394

Re: GBDK2020 - Is it smart trying to outsmart the compiler ?

Do you know that SDCC is doing the slower thing?
by lidnariq
Thu Apr 08, 2021 5:00 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1127

Re: SNES oscilloscope readings?

You could get one of the very cheap 8/16-channel ones. Search AliExpress for "fx2lp". You'll need all the probes, too, so it may not work out to a win to buy things piecemeal, though.

It's limited - only 12MSa/sec at 16 channel, but it's what I used for the PPU logic analyzer traces.
by lidnariq
Thu Apr 08, 2021 1:36 pm
Forum: Newbie Help Center
Topic: 4-screen VRAM and mappers
Replies: 3
Views: 255

Re: 4-screen VRAM and mappers

There are rather few mappers that explicitly can provide 4 nametables: NES-commerical era: mapper 4/206 = MMC3 or its simpler predecessor Namco 108 mapper 77 Games released for the "Vs System" arcade cabinets (and not at home) Modern homebrew era: mapper 30 = UNROM512 (INL 4sc variant) mapper 111 = ...
by lidnariq
Thu Apr 08, 2021 2:18 am
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1127

Re: SNES oscilloscope readings?

Is the S-CPU well enough understood Probably? a new-production chip Unaffordable. You can't get custom silicon without an initial outlay on the order of $80k+ in a pin-compatible package I've seen clever things with castellated PCBs and mezzanine connectors, such as the UltraPIF or fancy flex PCBs,...
by lidnariq
Wed Apr 07, 2021 1:55 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1127

Re: SNES oscilloscope readings?

In DogP's case, he was repairing the rarer Nintendo Super System arcade cabinets, so just buying SNESes for parts was a reasonable choice.
by lidnariq
Wed Apr 07, 2021 12:45 pm
Forum: NES Hardware and Flash Equipment
Topic: snes card 3v / 5v risk?
Replies: 31
Views: 6022

Re: snes card 3v / 5v risk?

Kayumba wrote:
Wed Apr 07, 2021 12:24 pm
Do you know what chip is it?
SD2SNES is Open Hardware, so you can look at the schematic and BOM yourself.
https://github.com/mrehkopf/sd2snes
by lidnariq
Wed Apr 07, 2021 12:36 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1127

Re: SNES oscilloscope readings?

Sure sounds like the S-CPU is toast there. You might find this: http://www.projectvb.com/nss/logs.htm informative