Search found 277 matches

by Fiskbit
Mon Jun 14, 2021 2:22 pm
Forum: NESemdev
Topic: Weird Zelda transition screen bug?
Replies: 8
Views: 555

Re: Weird Zelda transition screen bug?

You're right, modifying the game to not switch mirroring modes doesn't produce this behavior.

I'd be interested in seeing the full nametables during horizontal and vertical screen transitions; that might provide some clues.
by Fiskbit
Mon Jun 14, 2021 12:13 pm
Forum: NESemdev
Topic: Weird Zelda transition screen bug?
Replies: 8
Views: 555

Re: Weird Zelda transition screen bug?

MMC1 is able to switch mirroring modes by writing to bits 1-0 of register $8000-9FFF (https://wiki.nesdev.com/w/index.php/MMC ... .249FFF.29). It sounds like you don't currently support this. Zelda switches mirroring depending on the direction it is going to scroll.
by Fiskbit
Wed Jun 09, 2021 10:58 pm
Forum: NESdev
Topic: Problem with palette discoloration when PPU is turned off during rendering.
Replies: 15
Views: 1968

Re: Problem with palette discoloration when PPU is turned off during rendering.

Most AV Famicoms are rev H. Unless the serial number is fairly low, it should be H. What is the serial number?

Vectrex28 reports that he has seen this issue on his square button Famicom (A), frontloader (probably G), and round button Famicom (probably E or G).
by Fiskbit
Tue Jun 08, 2021 1:20 pm
Forum: NESdev
Topic: Problem with palette discoloration when PPU is turned off during rendering.
Replies: 15
Views: 1968

Re: Problem with palette discoloration when PPU is turned off during rendering.

This issue was also reported by Vectrex28 on the NESDev Discord about a week ago, though he didn't have a good test ROM yet, so thank you for posting one. It does sound like it's a previously-unknown, unemulated PPU glitch, though the mechanism is definitely not obvious. I've not tried it on real ha...
by Fiskbit
Tue May 25, 2021 11:58 am
Forum: NESemdev
Topic: Clock is skipped too late, relative to enabling BG
Replies: 3
Views: 1393

Re: Clock is skipped too late, relative to enabling BG

One thing to be aware of is that rendering toggle does not take effect immediately. There's a delay of a few dots (it's hard to be more precise than this, especially given CPU/PPU alignment variance), such that disabling rendering at 338 likely does not prevent the skipped dot because rendering actu...
by Fiskbit
Tue May 18, 2021 10:42 pm
Forum: NESdev
Topic: (NOOB) good MMC chip explanations/tutorials?
Replies: 31
Views: 9840

Re: (NOOB) good MMC chip explanations/tutorials?

DMC IRQ can also be used for timing splits, and while it's a bit intimidating to set up, it's ultimately not that bad once you figure it out.
by Fiskbit
Mon May 17, 2021 12:22 pm
Forum: Newbie Help Center
Topic: Famicom part of sprites are below where they should be
Replies: 5
Views: 3116

Re: Famicom part of sprites are below where they should be

I suspect this is the same issue I begin discussing here . Specifically, the PPU appears to be sensitive to activity on the CPU data lines, and this can cause it to suffer OAM corruption during vblank. It occurs on some systems with certain kinds of carts, FDS included, and is believed to be related...
by Fiskbit
Tue Apr 27, 2021 10:51 pm
Forum: General Stuff
Topic: Zelda II - The Adventure of Link... SUCKED
Replies: 30
Views: 12673

Re: Zelda II - The Adventure of Link... SUCKED

I know a lot of people who love this game and the thing that most appeals to them is the combat, which has a lot more depth and nuance than other games of the era. Unfortunately, I don't like this game much. I think these are my main issues with it: - The game feels like a platformer, but without mu...
by Fiskbit
Thu Apr 22, 2021 4:12 pm
Forum: NES Hardware and Flash Equipment
Topic: NES RAM upgrade
Replies: 18
Views: 6535

Re: NES RAM upgrade

I think you're making a lot of incorrect assumptions here. $0800-1FFF is not surely safe; it's entirely legal for a game to read from or write to $0800-1FFF in order to access $0000-07FF, and while I don't have any examples, I am sure they exist. Adding RAM in this region could break such games by m...
by Fiskbit
Thu Apr 22, 2021 11:25 am
Forum: NES Hardware and Flash Equipment
Topic: EverDrive-N8 Bank Switching issue
Replies: 19
Views: 6755

Re: EverDrive-N8 Bank Switching issue

If this is the original Everdrive N8 and not the Pro, you might be encountering general instability from the device. I've seen a lot of bug reports and videos of crashes and other bad behavior from N8 original users in official games and my own hacks which don't occur on emulator or other cart hardw...
by Fiskbit
Wed Apr 21, 2021 10:37 pm
Forum: NES Hardware and Flash Equipment
Topic: NES RAM upgrade
Replies: 18
Views: 6535

Re: NES RAM upgrade

A game can only map itself to portions of the address space that are open bus (ie where nothing else responds). $0800-1FFF and $3000-3FFF are not open bus; the former mirrors $0000-07FF and the latter mirrors $2000-2007. If the cartridge were to try to respond there, it would have a bus conflict wit...
by Fiskbit
Wed Apr 21, 2021 7:48 pm
Forum: NES Hardware and Flash Equipment
Topic: NES RAM upgrade
Replies: 18
Views: 6535

Re: NES RAM upgrade

While I encourage you to do this kind of thing for fun, I don't think this adds all that much value. Cartridges that need more RAM can simply include RAM themselves, and bankswapping to get to more RAM is not a significant enough restriction to sacrifice compatibility. How is this a better solution ...
by Fiskbit
Mon Apr 12, 2021 12:12 pm
Forum: NESemdev
Topic: Mesen - NES Emulator
Replies: 963
Views: 577166

Re: Mesen - NES Emulator

Most games shuffle the position of sprite tiles in OAM every frame, so this might not be as useful as you hope.
by Fiskbit
Fri Apr 02, 2021 9:42 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom Network System (aka Famicom Modem) Investigations
Replies: 161
Views: 133620

Re: Famicom Network System (aka Famicom Modem) Investigations

I've attached a photo of the error codes from the Kangyou Sumimaru no Famicom Trade manual. If I get a good opportunity to get at my other manuals, I'll post pictures from them, too.
by Fiskbit
Sun Mar 28, 2021 11:49 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom Network System (aka Famicom Modem) Investigations
Replies: 161
Views: 133620

Re: Famicom Network System (aka Famicom Modem) Investigations

It's Okasan (岡三), presumably for Okasan Securities, not okaasan (お母さん) meaning mother.