Search found 161 matches

by Fiskbit
Mon Sep 21, 2020 10:43 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

My assumption has been that the 3198 differences, internally, are purely software. Externally, the CIC is wired to receive a slot ID, which goes to pins 12-15 (P1.3 and P2.0-2). These are accessible with the in instruction, so I'm not sure why the chip hardware would differ. The bits that are misbeh...
by Fiskbit
Mon Sep 21, 2020 7:24 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

I don't know about that 2nd byte, but I don't think you're extracting the bottom 2 bits. Aside from that 32, every number looks like it ends in 0, 4, 8, or C. A lack of odd numbers would explain why there doesn't seem to be any code that can jump to banks 2 or 3.
by Fiskbit
Mon Sep 21, 2020 5:50 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

Do you have access to a CIC that has already been dumped so we can verify your output matches on that? I'm definitely skeptical about the 8's. Also, I notice that the repeat bytes at the end of the previous dump you posted (https://pastebin.com/JhWBFcAG) don't properly match the beginning. I'd expec...
by Fiskbit
Mon Sep 21, 2020 5:29 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

Jeroen: I think you're checking against 3193alfsr.bin instead of 3195alfsr.bin.
by Fiskbit
Mon Sep 21, 2020 5:19 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

It looks like the 8's bit is set in every byte now, which seems very unlikely to be correct.
by Fiskbit
Mon Sep 21, 2020 4:31 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

Another thing I've noticed about this dump: I don't see any 79's or 7D's in this code, so I'm not sure how it would be able to access banks 2 or 3. Bank 2 is pretty empty (only 20 bytes), but bank 3 has a lot in it.
by Fiskbit
Mon Sep 21, 2020 2:45 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

Is your coin timer CIC (3199) in any better shape? The FamicomBox/Station has a bunch of register bits for interacting with this CIC, so it might matter for emulation, but it's a much rarer chip because it's only in the console itself.
by Fiskbit
Sat Sep 19, 2020 9:41 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

This all matches up with my understanding. I'm a bit confused, though, that all of the CIC dumps I have are actually 512 bytes: 3193A, 3195A, 3197A, 6113, D411, and RFCCPU10. That last one is the ROB chip, I believe. All of these have $80 as the last byte for banks 0-2 and and $FF as the last for ba...
by Fiskbit
Fri Sep 18, 2020 10:13 pm
Forum: NES Hardware and Flash Equipment
Topic: Eccentric pedantic "monochrome" glitch
Replies: 5
Views: 197

Re: Eccentric pedantic "monochrome" glitch

I believe I've confirmed the emph2 case with the attached test ROM on a rev G frontloader. I manually hacked this one together in a hex editor from your binary, so no source for this. It writes #$81 to $2101 rapidly. On affected alignments, this will trigger white dots.
by Fiskbit
Fri Sep 18, 2020 3:27 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom 15 pin joypad - how it is wired?
Replies: 3
Views: 321

Re: Famicom 15 pin joypad - how it is wired?

There were two different ways 4 player Famicom games work. Games will either treat 4016.1 and 4017.1 as players 3 and 4, or they'll do the Four Score method of having two 8-bit devices and a signature on each of 4016.1 and 4017.1. The JoyPair gives you two ports and allows only the former, while the...
by Fiskbit
Fri Sep 18, 2020 7:05 am
Forum: NES Hardware and Flash Equipment
Topic: Eccentric pedantic "monochrome" glitch
Replies: 5
Views: 197

Re: Eccentric pedantic "monochrome" glitch

Wonderful, thanks for this test! You say shade of blue, but these should be white dots, right? Kitrinx identified that greyscale, emphasis 2, slave mode, and NMI enable are all implemented in this same way. I think this might explain the issue with Hi-Def NES and NESRGB mentioned here and seen here ...
by Fiskbit
Thu Sep 17, 2020 1:49 pm
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

Patnukem: I noticed the CIC on your cart is a 3198A. I received a couple FamicomBox carts yesterday that also use the 3198A. What are the revisions of the two CICs in your FamicomStation? It'd be good to get a dump of a letterless 3198, if we can find one.
by Fiskbit
Wed Sep 16, 2020 2:13 pm
Forum: NESemdev
Topic: PPU Cycle 0 convention and frame timing
Replies: 3
Views: 203

Re: PPU Cycle 0 convention and frame timing

1. The delay for settings in PPU MASK varies. Greyscale is known to be the fastest, and toggling rendering is the slowest. A test I posted here shows a 4 pixel difference when toggling greyscale and rendering at the same time (also shown in a screenshot there). Kitrinx, who implemented MiSTer's NES ...
by Fiskbit
Mon Sep 14, 2020 12:07 am
Forum: NES Hardware and Flash Equipment
Topic: Reverse Engineering the CIC
Replies: 501
Views: 225832

Re: Reverse Engineering the CIC

I've also picked up some CICs recently that I'm hoping to dump, including the two in the FamicomBox. I still need to get a way to actually collect the data. Sounds like you're a bit ahead of me. I think it'll be good to compare dumps to verify they're correct. I don't think the FamicomStation menu R...
by Fiskbit
Fri Sep 11, 2020 3:43 pm
Forum: NESdev
Topic: Overworld graphics bank swap to Zelda 1 MMC3 conversion?
Replies: 4
Views: 320

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

Don't choose MMC5. MMC3 does what you need and new MMC3 clone hardware is being made today. You just need to write to the appropriate MMC3 registers to do a CHR bankswap. Registers are documented on the wiki page here: https://wiki.nesdev.com/w/index.php/MMC3 . You write to the bank select register ...