Search found 1357 matches

by 93143
Mon May 10, 2021 3:36 pm
Forum: SNESdev
Topic: Fast 2D blitting on Super FX
Replies: 21
Views: 10543

Re: Fast 2D blitting on Super FX

...uh, that post is five years old. If you look a bit down the thread, you'll find that I've already tried it. It worked great - on a small round bullet, I got about 4/3 of the performance of a fast dither method. That's whole-program performance, not inner-loop performance, implying an even larger ...
by 93143
Sat May 08, 2021 5:03 pm
Forum: SNESdev
Topic: Fast 2D blitting on Super FX
Replies: 21
Views: 10543

Re: Fast 2D blitting on Super FX

The KISS principle is real. Last night I spent quite some time on what I thought was a really clever method of drawing a 1bpp dictionary-compressed graphic with the Super FX. It included brain-bending interwoven branches (at least, it was brain-bending at 3 in the morning) and took advantage of the ...
by 93143
Thu May 06, 2021 3:59 pm
Forum: General Stuff
Topic: How were Neo Geo games so big?
Replies: 12
Views: 1242

Re: How were Neo Geo games so big?

The N64 came out in 1997 [...] The Neo Geo has an 8MHz 68k 1996, and 12 MHz. Not that it makes much difference; the point stands... The N64 should be basically 10 times more capable than the Neo Geo in almost every regard. More like 17 times, going by a doubling every 18 months. (Then again, the Ne...
by 93143
Mon May 03, 2021 7:16 pm
Forum: GBDev
Topic: Super gameboy color?
Replies: 60
Views: 29834

Re: Super gameboy color?

If you press A, the code will try to write palette data when it detects Mode 3 for each scanline. The idea is to change it from blue to red. On certain emulators (notably my own and others like Mednafen) you'll see this change because they don't care about when the palette changes occur. On real ha...
by 93143
Sun May 02, 2021 12:13 pm
Forum: SNESdev
Topic: Using slow ROM for new games?
Replies: 31
Views: 14453

Re: Using slow ROM for new games?

That source just says you had to insert a NOP if your clock was higher than 4 MHz. Seems like something Ricoh could have fixed by inserting wait states. Or would it be too difficult to identify specific instructions coming in on the data lines without fiddling with the core?
by 93143
Sat May 01, 2021 8:43 pm
Forum: SNESdev
Topic: Need guidance with nes to snes.
Replies: 286
Views: 53979

Re: Need guidance with nes to snes.

Sorry if I'm a bit short-tempered lately... I just remembered one more thing. An interrupt causes the program bank to reset to $00 (it's recovered when returning from the interrupt), so if there's any code in the bankswitched sections you may want to do a long jump to the desired bank at the beginni...
by 93143
Sat May 01, 2021 5:05 pm
Forum: SNESdev
Topic: Need guidance with nes to snes.
Replies: 286
Views: 53979

Re: Need guidance with nes to snes.

My NMI does not start and finish in a 16bit state. I've tried implementing that several different time and it just doesn't work for me There aren't really any subtle gotchas as far as I'm aware; it should work in every case if you do it right. The only potential issue here is stack overflow. If you...
by 93143
Sat May 01, 2021 3:36 pm
Forum: SNESdev
Topic: Need guidance with nes to snes.
Replies: 286
Views: 53979

Re: Need guidance with nes to snes.

HDMA is not faster than regular DMA at anything regular DMA can do. It's a bunch of small transfers in between scanlines, so the overhead associated with a single DMA transfer gets applied multiple times, and the base data transfer rate is the same, so HDMA can only be slower. You also can't assume ...
by 93143
Fri Apr 30, 2021 8:49 pm
Forum: SNESdev
Topic: Need guidance with nes to snes.
Replies: 286
Views: 53979

Re: Need guidance with nes to snes.

$4212 doesn't do anything; it's just information. $4210 should be read during NMI. $4211 should be read during an IRQ.
by 93143
Thu Apr 29, 2021 9:47 pm
Forum: SNESdev
Topic: Using SPC for music and sound effects in non-SNES game
Replies: 4
Views: 842

Re: Using SPC for music and sound effects in non-SNES game

A SNES emulator with debugging features should allow you to see what it does to the I/O ports, and may also allow you to debug APU-side code. Also note that I cannot advise you on legal issues; the fact that I have engaged with your questions is not intended to imply that your project is safe from l...
by 93143
Thu Apr 29, 2021 7:57 pm
Forum: SNESdev
Topic: Using SPC for music and sound effects in non-SNES game
Replies: 4
Views: 842

Re: Using SPC for music and sound effects in non-SNES game

An SPC isn't a sound file. It's a machine state snapshot of the SNES APU, which includes its own CPU and runs code written by the developer. Normally (there are exceptions), games use the I/O ports to communicate events, like sound effects, and then the audio engine in the APU handles the details. T...
by 93143
Sun Apr 25, 2021 8:17 pm
Forum: SNESdev
Topic: SNES Music Pack 1 by Resistance
Replies: 17
Views: 4698

Re: SNES Music Pack 1 by Resistance

Oh yeah, I remember. A number of games are undumpable as SPC, not because of sample streaming, but because of note data being supplied in real time by the S-CPU. I suspect NBA Live '96 did this because they filled ARAM too full of samples. Wolfenstein 3D seems to do this too, and it has no excuse* b...
by 93143
Sun Apr 25, 2021 12:51 pm
Forum: SNESdev
Topic: SNES Music Pack 1 by Resistance
Replies: 17
Views: 4698

Re: SNES Music Pack 1 by Resistance

There's not much point in using more than one HDMA channel for streaming, as a single channel can saturate the I/O ports on its own. The SPC700 can't turn around anywhere near fast enough to handle more than one four-byte shot in a single HBlank. Also, real streaming music eats a lot of ROM. If you ...
by 93143
Tue Apr 13, 2021 4:05 pm
Forum: SNESdev
Topic: Need guidance with nes to snes.
Replies: 286
Views: 53979

Re: Need guidance with nes to snes.

The "horizontal" in H-IRQ refers to the position at which it fires. It uses a dot position within a scanline as its trigger, so as to fire at the same horizontal coordinate every line (roughly - there's some jitter due to instruction execution having to finish before the IRQ actually happens). When ...
by 93143
Mon Apr 12, 2021 7:39 pm
Forum: SNESdev
Topic: Need guidance with nes to snes.
Replies: 286
Views: 53979

Re: Need guidance with nes to snes.

What do you mean by "splits the screen from left to right"? Do you mean that there's a region on the left and a region on the right, separated by a vertical line? Or do you mean there's a region on top and one on the bottom, separated by a horizontal line? If the former, my guess is that it has noth...