Search found 62 matches

by andlabs
Thu Apr 05, 2012 8:40 pm
Forum: Demos
Topic: Axelay scroll proof of concept
Replies: 17
Views: 10056

I'm guessing more people will recognize it by calling it "mode 7" even though it's not what it actually is. I've been on your side of the fence too :/
by andlabs
Tue Mar 27, 2012 5:33 pm
Forum: Tools
Topic: VGM Music Maker
Replies: 93
Views: 42417

Derp I didn't see that =P I'll give that a try then, thanks :)
by andlabs
Tue Mar 27, 2012 4:15 pm
Forum: Tools
Topic: VGM Music Maker
Replies: 93
Views: 42417

Would you mind releasing an specification of the vge file format? I would like to write a program that converts VGE files to Sik's echo sound driver's format. Thanks.
by andlabs
Fri Jan 27, 2012 6:00 pm
Forum: Megadrive/Genesis
Topic: F-22 Interceptor oddness?
Replies: 5
Views: 2617

That isn't only known; that also appears to have been intentional, since one of the compilations (possibly the Sega Ages one on the Saturn) also has its data split like that.. The 8-bit ROM mapping is what I was thinking of when I made the OP; I could take a look at a disassembly later and see what ...
by andlabs
Thu Jan 26, 2012 11:01 pm
Forum: Megadrive/Genesis
Topic: F-22 Interceptor oddness?
Replies: 5
Views: 2617

F-22 Interceptor oddness?

Overlord dumped a bunch of EU carts he had to check for alternate revisions, and his September 1991 copy of F-22 Interceptor didn't match any of our existing dumps (no-intro). It turns out that every other byte starting at $80000 is different — but all are identical. And it's the same situation in e...
by andlabs
Mon Nov 28, 2011 1:49 pm
Forum: Pico
Topic: Sega Pico
Replies: 2
Views: 6075

PCM format is known; it's used by System C2 and various other Sega arcade hardware. The main difference (as far as I can tell) between µPD7759 and other members of the µPD7755 family (under which you'll find it in the Renesas archives, as Renesas now owns NEC Semiconductor's assets) is that this chi...
by andlabs
Fri Nov 11, 2011 5:22 am
Forum: Megadrive/Genesis
Topic: Can external programs access ram data used by emulators?
Replies: 1
Views: 1252

Not in a safe, direct, and reliable way unless the emulator author provided such a means. Gens/GS (not yet with Gens/GS II) does give you the ability to write plugins; I don't know the specifics and you'd have to talk to GerbilSoft about it. You could write that capability into Gens (preferably a ne...
by andlabs
Fri Nov 11, 2011 1:17 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 859
Views: 478263

In addition to the questions I asked above, I have a few others: With regards to the SSG-EG register, the YM2149 datasheet and Neo-Geo manual (YM2610) all list inverted normal output for any combination 01xx (that is, 01xx behaves like 1111), but that's not what we have down for YM2612, and the YM34...
by andlabs
Tue Nov 08, 2011 6:20 pm
Forum: Tools
Topic: VGM Music Maker
Replies: 93
Views: 42417

Bug: @:1 TBBPC3.MDX-@1 LFO: 128 64 64 0 0 CH:192 7 2 0 0 120 0 M1: 31 7 3 5 2 36 1 1 3 0 0 C1: 31 3 4 5 2 48 0 5 2 0 0 M2: 31 3 2 5 1 36 0 3 6 0 0 C2: 28 30 7 6 0 0 2 1 0 0 0 The first notes per channel in this voice played from the tracker won't be audible; all future notes will be. Exported VGMs p...
by andlabs
Sat Oct 22, 2011 4:48 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 859
Views: 478263

Good to know, thanks. Thinking about it some more, wouldn't the EG also run independently of the phase and output generators? The MAME source code implies that the global cycle counter is global to all channels, is this really the case? If so there's really no other way to have the EG work... as far...
by andlabs
Wed Oct 19, 2011 2:39 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 859
Views: 478263

This is what I can gather/guess about what happens on each YM2612 cycle, am I correct? if current channel is channel 6 in PCM mode output PCM byte to DAC if 4*NCYCLES_PER_OPERATOR cycles passed move to next channel else run SSG-EG for current channel if NCYCLES_PER_EGUPDATE cycles passed update EG f...
by andlabs
Wed Oct 12, 2011 4:57 pm
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 859
Views: 478263

Thanks; I'll take a look into these since they look like they would be more effective in understand the chip =P However I think I misstated my first question: I meant what was the calculation for the array itself? EDIT wait I see, it's the "Where Block is the 3-bit block data, and N4/N3 are built fr...
by andlabs
Wed Oct 12, 2011 2:35 pm
Forum: Megadrive/Genesis
Topic: Are we sure MD Z80 can't write to M68K RAM? NCS does it...
Replies: 24
Views: 10882

As far as I know it does not write $A11000. I'd have to look into how the A-line opcodes, which it seems to use for some VDP accesses, works. The sound driver only writes values once before continuing. The write to $FF0800 happens once a nonzero value is written to Z80 $1BFB. The only reference to t...
by andlabs
Wed Oct 12, 2011 2:24 pm
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 859
Views: 478263

These have probably been answered here before and this may not be the right topic for the latter question but :/ I'm trying to figure out how the YM2612 works by reading the MAME code... 1) I understand that "int ksr = kc >> SLOT->KSR" (in refresh_fc_eg_slot) gets what the YM2608 translated doc call...
by andlabs
Fri Oct 07, 2011 3:25 pm
Forum: Megadrive/Genesis
Topic: Are we sure MD Z80 can't write to M68K RAM? NCS does it...
Replies: 24
Views: 10882

I still need to look into it, however my guess is that the $FF0800 is a flag used to indicate music is ready to play or something, since it doesn't lock up until a level is loaded. Apparently this game uses the NCS/Explode Star sound driver, which was only used in two other games: Trampoline Terror!...