Search found 27 matches

by Kabuto
Sun Dec 07, 2014 12:27 am
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

@Chilly Willy: Interesting. What's the trick you're talking about? @Mask of Destiny: yeah, one of the many fixes I'm gonna do. Might be tricky as no emulator exhibits this behaviour (but I got a modded MD2 that does) @bastien: nice to hear, thanks :) Regarding the z80 access timings, tests on a real...
by Kabuto
Fri Dec 05, 2014 8:34 pm
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Guess I'll be able solve the IRQ troubles in a neat way, no more timing shenanigans ;) Basically, there have been 2 issues that made me block IRQs for longer timeframes. One is that I need to halt the z80 for writing to its memory (IRQs would prolong that too much and cause well audible glitches), t...
by Kabuto
Wed Dec 03, 2014 11:27 pm
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Very interesting. I thought it was about whole instructions, but that makes my life easier a bit :) Just had a look at some z80 docs I found on the web, and made this list of 6T instructions: * all that transfer from or to the SP register * INC/DEC 16-bit-reg and 5T instructions: * all that use (IX+...
by Kabuto
Wed Dec 03, 2014 12:21 am
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Regarding jitter, I remember doing tests for how much delay is acceptable before jitter becomes an issue, and guess what, different values for real hardware and all emulators tested (regen and exodus). But I didn't do any measurements in this case here, maybe there is some jitter and it's just diffi...
by Kabuto
Mon Dec 01, 2014 11:28 pm
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Haha, this SRAM trick is nice :)

Though there's one caveat: accesses to this area have to use the 68k bus too, and that would halt the Z80 as well during DMA transfers
by Kabuto
Mon Dec 01, 2014 10:58 pm
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

I'm writing 2 samples at once. I mix one sample (-> 16 bits), then use "swap" to shift the word to the upper half of its register, then mix another sample, and then write both at once to z80. I only hog the z80 bus for this short time frame so the z80 code does not get halted for too long which woul...
by Kabuto
Mon Dec 01, 2014 10:30 pm
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Stef: any mod file that plays on amiga should play on MD as well. The mod file format has a limit of 128 KB for samples and 31 samples total. Chilly Willy: true, that's how it's done, the z80 could never do that on its own... though just start counting cycles, and it won't look that easy any more ;)...
by Kabuto
Mon Dec 01, 2014 10:26 am
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Thanks :) I'm detecting it by silently playing a number of samples on the z80 and running a busy loop on the 68k, and then, when the 68k finishes, checking how many samples the z80 could play. Had to add this because it sounded horrible in some emulators (regen with default settings, gens). I have n...
by Kabuto
Mon Dec 01, 2014 12:48 am
Forum: Demos
Topic: Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player
Replies: 32
Views: 8418

Iron Maiden chiptune musicdisc + 26 kHz mod/ahx player

Grab it here: http://www.pouet.net/prod.php?which=64438 This was just released this weekend, a music disc (or rather: cartridge) full of iron maiden chiptune covers with some nice gfx too. This features a mod+ahx player, made for this project, which mixes 4 PCM channels with individual volume and pl...
by Kabuto
Tue Sep 10, 2013 3:36 pm
Forum: Megadrive/Genesis
Topic: Mickey Mania emulator comparison
Replies: 67
Views: 26771

A few comments about this scene: * Yes, it tries to align the start. But there's the Z80 which is randomly stealing cycles and thus there's still a lot of randomness in the timing. I aligned it to the earliest position that doesn't create bugs on real hardware to reduce the number of bugs due to del...
by Kabuto
Mon Aug 26, 2013 7:09 pm
Forum: Demos
Topic: wolfenstein demo for sega genesis
Replies: 361
Views: 145496

On Pal MD with RF output 101010-like patterns are perfectly blurred as well, probably to avoid luma/chroma crosstalk. You could also trade resolution for speed by halving vertical resolution: * Either render at halved vertical resolution, then DMA that to the VDP, then reduce vscroll by 1 every 2nd ...
by Kabuto
Sun Aug 25, 2013 7:03 pm
Forum: Demos
Topic: overdrive
Replies: 42
Views: 14289

Did you try disabling the in-game menu in the Mega Everdrive options? Can anyone who's got a Mega Everdrive make tests whether enabling/disabling that option changes anything? The manual says "Some games may not work or may be operate erratically if In-game Menu option is enabled" - I don't have a M...