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SubjectNeoGeo sound emulation help new Reply to this message
Posted bymasterzog
Posted on09/22/07 10:56 PM



Any NeoGeo authors have any tips about getting sound to work?

I have the Z80 running, and I pass the bios Z80 check. However, the ym2610 never gets a request to start an adpcm channel (I don't even care about the FM stuff yet).

I have the ym2610 timers running, and I've verified they are sending IRQs to the Z80. I'm giving the Z80 a NMI when the 68k sends a sound command.

I don't have much debugging capability on my target system, so it's hard for me to track down problems. Any insights would be very much appreciated.


SubjectRe: NeoGeo sound emulation help new Reply to this message
Posted byHyde
Posted on09/24/07 04:44 PM



Not that this will answer your question or anything, but I am interested in knowing where you got the documentation necessary for building a Neo Geo emulator. I am looking for references besides the traditional "Go look at the MAME source you n00b".


SubjectRe: NeoGeo sound emulation help Reply to this message
Posted bymasterzog
Posted on09/24/07 06:38 PM



This site is good: http://cgfm2.emuviews.com/temp/mvstech.txt (it's credited at the top of the mame source)

This site is ok too: http://arcadedev.emuvibes.com/ (read the neogeo spex doc)

Although I've found mame to be more useful than either of these. You can also look at other emulators like gngeo and final burn alpha. Interestingly, I've found the psp neogeo/cpsX emulator to be very easy to read. Once you read the above docs, the emulator source code will probly make more sense (it did for me).

> Not that this will answer your question or anything, but I am interested in
> knowing where you got the documentation necessary for building a Neo Geo
> emulator. I am looking for references besides the traditional "Go look at the
> MAME source you n00b".
>





SubjectRe: NeoGeo sound emulation help new Reply to this message
Posted byAamirM_Nugen
Posted on09/25/07 02:35 AM



Hi,

I suggest that you take a look at Final Burn Alpha and gngeo sources. Sound support is a bit tricky to get working. Also make sure that your memory and Z80 port handlers are set-up correctly.

stay safe,

AamirM

PS: I am a Neogeo emu author :) (download the beta version from http://www.mytempdir.com/2022594)

> Any NeoGeo authors have any tips about getting sound to work?
>
> I have the Z80 running, and I pass the bios Z80 check. However, the ym2610
> never gets a request to start an adpcm channel (I don't even care about the FM
> stuff yet).
>
> I have the ym2610 timers running, and I've verified they are sending IRQs to the
> Z80. I'm giving the Z80 a NMI when the 68k sends a sound command.
>
> I don't have much debugging capability on my target system, so it's hard for me
> to track down problems. Any insights would be very much appreciated.
>





SubjectRe: NeoGeo sound emulation help new Reply to this message
Posted bymasterzog
Posted on09/25/07 01:20 PM



Well I finally have some stuff working (and it is indeed tricky).

One interesting thing I've noticed after reading the code over and over is that mame doesn't seem to use the bios z80 driver at all. It loads it in initially, but as soon as the driver inits, the cart z80 driver gets loaded in and never switches back. I do the same in my emulator and it seems to work fine.

The relevant code is this (in neogeo.c, ~line 742):

static void _set_audio_cpu_rom_source(void)
{
/* if (!memory_region(NEOGEO_REGION_AUDIO_CPU_BIOS)) */
audio_cpu_rom_source = 1;

memory_set_bank(NEOGEO_BANK_AUDIO_CPU_MAIN_BANK, audio_cpu_rom_source);
...

The commented line looks like it was origonally a fallback in case the bios z80 rom didn't exist. But as it stands, this will skip the bios in all cases.

> Hi,
>
> I suggest that you take a look at Final Burn Alpha and gngeo sources. Sound
> support is a bit tricky to get working. Also make sure that your memory and Z80
> port handlers are set-up correctly.
>
> stay safe,
>
> AamirM
>
> PS: I am a Neogeo emu author :) (download the beta version from
> http://www.mytempdir.com/2022594)
>
> > Any NeoGeo authors have any tips about getting sound to work?
> >
> > I have the Z80 running, and I pass the bios Z80 check. However, the ym2610
> > never gets a request to start an adpcm channel (I don't even care about the FM
> > stuff yet).
> >
> > I have the ym2610 timers running, and I've verified they are sending IRQs to
> the
> > Z80. I'm giving the Z80 a NMI when the 68k sends a sound command.
> >
> > I don't have much debugging capability on my target system, so it's hard for
> me
> > to track down problems. Any insights would be very much appreciated.
> >
>





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