Search found 89 matches

by TakuikaNinja
Sat Mar 23, 2024 12:09 am
Forum: NESdev
Topic: Wiki: 6502 assembly optimisations - possible mistake
Replies: 5
Views: 520

Re: Wiki: 6502 assembly optimisations - possible mistake

Be careful with how you negate the immediate value there. Assemblers use the arithmetic/bitwise functions from their standard programming language library (e.g. C) which can return a 16-bit word. That's why the wiki has ADC #<-value , it's explicitly specifying the lower byte of the negation result....
by TakuikaNinja
Thu Mar 21, 2024 4:35 am
Forum: NESdev
Topic: Family BASIC on the FDS, from the 80's
Replies: 1
Views: 289

Family BASIC on the FDS, from the 80's

If you're going to make a Disk Operating System for the FDS, you might as well port Family BASIC to it. Backwards compatibility with user programs on tape would have been a consideration if it was done back then. Also, the FDS BIOS includes a keyboard reading routine at $EB13 but its implementation...
by TakuikaNinja
Thu Mar 07, 2024 3:36 pm
Forum: NES Music
Topic: Famitracker not exporting NSf correctly
Replies: 5
Views: 374

Re: Famitracker not exporting NSf correctly

It might be best to test the NSF file with a traditionally compliant player such as NSFPlay.
by TakuikaNinja
Thu Mar 07, 2024 3:33 pm
Forum: NES Music
Topic: Famitracker not exporting NSf correctly
Replies: 5
Views: 374

Re: Famitracker not exporting NSf correctly

Make sure the engine speed and NSF region are matching, or choose "dual region". Otherwise, there may be something going on with your console setup. Is it specifically a PAL console? You may need to hit reset 7 times to cycle between CIC regions on the Everdrive (it could be the case that ...
by TakuikaNinja
Sat Mar 02, 2024 8:31 pm
Forum: NES Music
Topic: Famitracker not exporting NSf correctly
Replies: 5
Views: 374

Re: Famitracker not exporting NSf correctly

Did you set the engine speed to PAL? It's different from the one in the export dialog.
by TakuikaNinja
Fri Mar 01, 2024 1:29 am
Forum: NES Hardware and Flash Equipment
Topic: Xi Tian Qu Jing II (Unl) Crash Issue
Replies: 8
Views: 583

Re: Xi Tian Qu Jing II (Unl) Crash Issue

You're right, it's Dendy, not PAL. The ROM I found called it PAL (and uses an iNES header, which doesn't really specify), but the NES 2.0 database used by Mesen contains this game and correctly marks it as Dendy. Mesen has an Auto region feature that will automatically run the game according to the...
by TakuikaNinja
Wed Feb 28, 2024 9:01 pm
Forum: NES Hardware and Flash Equipment
Topic: Xi Tian Qu Jing II (Unl) Crash Issue
Replies: 8
Views: 583

Re: Xi Tian Qu Jing II (Unl) Crash Issue

Yeah, it seems like it's relying on "Dendy" timing during bulk PPU transfers with rendering disabled. An NMI can interrupt it and switch banks when it wasn't supposed to. Most common dumps seem to have a bad header that don't specify the correct frame timing, which some emulators mitigate ...
by TakuikaNinja
Thu Feb 22, 2024 7:33 pm
Forum: NESemdev
Topic: How are SFX played over music?
Replies: 7
Views: 543

Re: How are SFX played over music?

I'm not sure what you're trying to do here. The NSF format has no notion of SFX interrupting playback. Rips with SFX just assign them to unique tracks and expect that players will completely reset their internal state before playing them. If this is for playing music and SFX in NES software/games, t...
by TakuikaNinja
Mon Feb 19, 2024 3:49 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom freezing...
Replies: 4
Views: 360

Re: Famicom freezing...

That sounds like a sprite zero hit is being missed? Double check that the cartridge pins and the Famicom's cartridge connector are clean first. Isopropyl alcohol applied to a cotton bud is the common recommendation. Ejecting and reinserting the cart a few times can also help scrape some of the corro...
by TakuikaNinja
Fri Feb 16, 2024 2:03 am
Forum: NESdev
Topic: Final Fight 3 (mapper 90), get rid of multiplier, issues
Replies: 12
Views: 3091

Re: Final Fight 3 (mapper 90), get rid of multiplier, issues

The checksum routine and the mention of anti-debugging traps in a multicart version just screams copy protection. Using the actual multiplier was likely a lower priority to the developers.
by TakuikaNinja
Wed Feb 07, 2024 5:00 am
Forum: NESdev
Topic: Issues with making MMC1 pach for: Bio Senshi Dan - Increaser tono Tatakai
Replies: 2
Views: 331

Re: Issues with making MMC1 pach for: Bio Senshi Dan - Increaser tono Tatakai

The bankswitch being done in the subroutine at $FE65 (called after setting the scroll values for the action area) seems to be going wrong. It tries to bankswitch with A=#$10 which is PRG bank 1 and CHR bank 0 (in terms of 32K & 8K banks respectively), calls the subroutine at $F4F6, then restores...
by TakuikaNinja
Mon Feb 05, 2024 6:22 pm
Forum: NESdev
Topic: Kaiketsu Yanchamaru 3 - PPU EXT output mode
Replies: 4
Views: 464

Re: Kaiketsu Yanchamaru 3 - PPU EXT output mode

I have this stupid theory where programmers may have misunderstood the EXT output mode as something which needed to be set before writing to VRAM. I like to think it's a bit more plausible than it being for debugging reasons. By the way, I think it may be a good idea to document that game list on th...
by TakuikaNinja
Mon Feb 05, 2024 5:47 pm
Forum: NESdev
Topic: Kaiketsu Yanchamaru 3 - PPU EXT output mode
Replies: 4
Views: 464

Re: Kaiketsu Yanchamaru 3 - PPU EXT output mode

I don't know/remember if Nintendo documents themselves say anything against setting this bit, either. I checked the Famicom documentation on archive.org and I can't seem to find any mention of the EXT output mode being dangerous on a stock console. It does provide a example schematic of a "mas...
by TakuikaNinja
Thu Jan 18, 2024 11:27 pm
Forum: NESdev
Topic: FDS Timer Interrupt for OS-Style Time Slices?
Replies: 30
Views: 4682

Re: FDS Timer Interrupt for OS-Style Time Slices?

Stuff like that is what I meant when I said that the emulation scene has ignored the low-level details of the FDS. No one ever bothered to emulate it accurately because no commercial game relies on its exact behaviour (i.e. compatibility came first). It might be worth creating a separate thread to p...
by TakuikaNinja
Tue Jan 16, 2024 4:49 am
Forum: NESdev
Topic: SMB3 with Save patch - issues on real cartridge
Replies: 5
Views: 1399

Re: SMB3 with Save patch - issues on real cartridge

Good luck getting touch with the author, who has likely moved on from ROM hacking altogether by now.
I had a quick look and it seems that while the NMI handler does run, it goes through a code path which does not decrement $10 (the "NMI occurred" flag).