Search found 238 matches

by Fiskbit
Tue Dec 22, 2020 7:10 pm
Forum: NESdev
Topic: List of games that use power-on state to seed RNG
Replies: 36
Views: 4107

Re: List of games that use power-on state to seed RNG

This inc PPUADDR to reuse the PPU's I/O data bus value as a VRAM address is beautiful. Even more dastardly would be inc PPUDATA to exploit the reported inability to write to video memory on consecutive M2 cycles. INC on $2007 is unfortunately not nearly as simple as just ignoring a write. I looked ...
by Fiskbit
Tue Dec 22, 2020 4:16 pm
Forum: NESemdev
Topic: mmc3c decap and trace
Replies: 13
Views: 1339

Re: mmc3c decap and trace

The reason for MMC5's snooping on accesses to $2002, $2005, $2006 (MMC5A), and $4014 isn't known, and MMC5A appears to respond to writes to $5800-5BFF for unknown reasons. Definitely still some mysteries, though nothing that likely matters for existing games.
by Fiskbit
Mon Dec 21, 2020 1:05 am
Forum: NESdev
Topic: Overworld graphics bank swap to Zelda 1 MMC3 conversion?
Replies: 27
Views: 7322

Re: Overworld graphics bank swap to Zelda 1 MMC3 conversion?

I spent about 4 hours putting together a proof of concept using MMC1 and 32 KB of CHR-RAM, currently just animating the waterfall. It targets PRG0 (PRG1 will likely require changing some addresses). It uses 4 KB CHR mode and swaps the entire background table at once (between banks 1-4). The automap ...
by Fiskbit
Sat Dec 19, 2020 11:10 pm
Forum: NESdev
Topic: Overworld graphics bank swap to Zelda 1 MMC3 conversion?
Replies: 27
Views: 7322

Re: Overworld graphics bank swap to Zelda 1 MMC3 conversion?

Zelda 1 uses 8 KB of CHR-RAM, not CHR-ROM, so it'd have to be converted to CHR-ROM to allow the swapping necessary for this (though I don't know if there's anything aside from emulator compatibility that would prevent you from having bankable CHR-RAM on MMC1). CHR-ROM, though, doesn't seem very comp...
by Fiskbit
Sat Dec 19, 2020 5:31 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom Network System (aka Famicom Modem) Investigations
Replies: 84
Views: 43673

Re: Famicom Network System (aka Famicom Modem) Investigations

Nice findings! Does $40C0.0 control the modem's WRAM, too, or just cartridge RAM? I've seen that official code writes 0 to $40AE before 0 to $40C0.0, and 1 to $40C0.0 before 1 to $40AE. They're always a pair. I've assumed that these enable/disable the modem's WRAM, but I haven't tested this because ...
by Fiskbit
Thu Dec 17, 2020 1:14 am
Forum: NESdev
Topic: List of games that use power-on state to seed RNG
Replies: 36
Views: 4107

Re: List of games that use power-on state to seed RNG

I don't know the details, but I believe Ridley's behavior in Metroid depends on uninitialized RAM. This causes speedrunners to seek out specific consoles (usually toploaders) or use flash carts with firmware that leaves favorite values in RAM.
by Fiskbit
Wed Dec 16, 2020 4:19 am
Forum: NES Hardware and Flash Equipment
Topic: DeGlitching ppuA12 on mmc3 by software (vhdl or others)
Replies: 6
Views: 1681

Re: DeGlitching ppuA12 on mmc3 by software (vhdl or others)

The jitter in Steins;Gate is just a matter of the split not being timed properly. I've written a patch to fix it and the other visual issues I'm aware of (split timing with DPCM playing; color artifacts from the palette swap; blacker than black in the palette fades), but have been wanting to play th...
by Fiskbit
Tue Dec 15, 2020 10:10 pm
Forum: NES Hardware and Flash Equipment
Topic: Kazzo USB rom dumper / dev cart programmer
Replies: 709
Views: 381059

Re: Kazzo USB rom dumper / dev cart programmer

I've been using the INL dumper primarily for Famicom modem carts, which all use MMC1 and mostly dumped fine with the existing MMC1 script. However, a handful of carts didn't dump correctly and would come out different each time, being mostly correct but with bit flips in bytes at certain address off...
by Fiskbit
Tue Dec 15, 2020 8:17 pm
Forum: NES Hardware and Flash Equipment
Topic: Kazzo USB rom dumper / dev cart programmer
Replies: 709
Views: 381059

Re: Kazzo USB rom dumper / dev cart programmer

What sort of output do you get when you try to dump Mei Tantei Holmes? It looks like a pretty standard MMC1 game, with 256 KB ROM and CHR-RAM. The current MMC1 script is definitely not comprehensive, but I'm pretty sure it should handle that just fine.
by Fiskbit
Sun Dec 13, 2020 6:26 am
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 596
Views: 266703

Re: Reverse Engineering the CIC

Does the older menu cart have different software on it? I'm even more interested in dumps of these now; I'd love to see what's different. FYI, if you want a general-purpose cart dumper, I've been pretty happy with the INL dumper. While it doesn't have scripts for everything yet, it'll handle the men...
by Fiskbit
Sun Dec 13, 2020 6:03 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom Network System (aka Famicom Modem) Investigations
Replies: 84
Views: 43673

Re: Famicom Network System (aka Famicom Modem) Investigations

Ben and I were able to get reading and writing of the microwire EEPROM to work from test software. Here's the setup you need: - Ensure modem WRAM is off by writing 0 to $40AE and $40C0.0. - Ensure cartridge SRAM is off by keeping $A000.4 high. - Write 0 to $E000.4 to enable EEPROM data out (DO). - W...
by Fiskbit
Fri Dec 11, 2020 6:34 pm
Forum: General Stuff
Topic: Determining a file's content type without extension
Replies: 14
Views: 2234

Re: Determining a file's content type without extension

Well, you started this conversation by calling the use of file extensions for program association 'stupid' and then kept making prescriptive statements about how things should be done, which isn't exactly useful. Explaining why lets us understand the problems with this system and the value of your s...
by Fiskbit
Fri Dec 11, 2020 2:49 am
Forum: General Stuff
Topic: Determining a file's content type without extension
Replies: 14
Views: 2234

Re: Determining a file's content type without extension

A file browser should be able to launch applications based on the content, not the filename. It should also be able to have overrides, both on a per-file and per-directory basis. Applications should always validate the data they are given before doing anything. It shouldn’t trust the filename. In f...
by Fiskbit
Fri Dec 11, 2020 1:06 am
Forum: NESdev
Topic: Vs System Shared Memory
Replies: 48
Views: 6301

Re: Vs System Shared Memory

I regularly see assert to mean to make a thing active, whether that's active low or high. I'm in favor of using it in this case. Using the definition instead of the word will certainly be clearer to someone who hasn't encountered this word in this context before, but less clear to people who know th...
by Fiskbit
Wed Dec 09, 2020 7:51 pm
Forum: NESdev
Topic: Vs System Shared Memory
Replies: 48
Views: 6301

Re: Vs System Shared Memory

This may be wrong, but I'd thought this issue is solved with the volatile keyword, telling the compiler not to cache the variable and that it should be reaccessed on each use.