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FamiTracker
Started a little [url=http://forums.nesdev.com/viewtopic.php?f=9&t=9323]thread over at NESdev to try to get some closure and development in getting these games fully decapped so that we can accurately emulate them.
Eventually NSFPlay and FamiTracker could potentially use the ADPCM dumped samples from the 220, 186, and 148 carts with a custom NSF driver to create cute little Baseball or Tennis themed songs. Pretty sure the Japanese at FamiCompo would really like it!
On the Famicom, the D7756C sample data is access with register $7000-7FFF.
[quote="NESdev Wiki"]7654 3210
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It can hold 16x16KB ADPCM samples in its 256K area of sample space on the D7756C. These samples are decoded to 9-bit PCM and played out the expansion audio pins. Other models had a larger area for sample space. Note: They are NOT located on the PRG ROM! Each of these chips were programmed in the factory to have a set number of samples specified by the company purchasing the chips. Ex: Jaleco specified the samples within the D7756C 220, 186, and 148 carts.
To push the format even further instead of FamiTracker just supporting the D7756C it could technically support the D77[b]P[/b]56 which was the 256K user-programmable variety. In that same sake, we could supply 16x16K ADPCM samples of our own.
To keep things accurate as possible, a "hack" would be if someone programmed a D77P56 and replaced it on the PCB. Non-hacked ROMs/NSFs would use the stock samples provided by Jaleco.
Also to make things even more fun, I've been looking at [url=http://www.taobao.com]Taobao a lot for imported games, Famicom carts, parts for console hacking and refurbishing, etc. They also have a lot of neat ICs for sale. They even have a lot of RP2A03x's! If someone is able to decap and dump some ICs, we could decap and dump the samples from other D775xx chips. Most of these were probably used in very well-known arcade games... (This could also help with the MAME and MESS projects.)
FamiTracker or Deflemask could maintain the ADPCM sample banks for whichever chip we desire and append the samples at the end of the NSF for access. This way we could create some remixes of other Famicom and arcade games with ADPCM to 9-bit PCM samples... This could also keep the development of NES/Famicom emulation/composing relatively fresh so we don't run out of things to do. :P
Emulated players could just keep the samples in PC/phone/tablet RAM. Hardware players would have to use its own RAM; which may be an issue -- Unless some new type of flash cart has some other type of onboard flash RAM.
Edit: [url=http://forums.nesdev.com/viewtopic.php?f=9&t=9006]ENIO may be the answer for this dilemma.
Sure! I haven't heard of this before but if it is a valid sound chip that eventually is supported by NSF then I don't see any problems of adding it to Famitracker. At least not if custom samples would be supported, but I'm not sure how that would be handled by NSF since all memory is currently CPU mapped. NSF2 extension?
The information seems a little sparse. Do you know if any emulator currently supports this?
Emulators like [url=http://forums.emulator-zone.com/showthread.php?t=6607]Nestopia support it in a hacked round-about way. They play WAVs when $7000-7FFF are read. The actual encoded ADPCM format is unknown at the moment. We need to read the samples out from the D7756C chips before we really know.
The real benefit of this is that the samples are read and processed internally within the D7756C and the 2a0x has no idea they even exist. They are processed and pumped out of the expansion audio pins. This means you wouldn't have to take much to any timing differences in account with your current engine. Just means 16 more samples coupled with existing DPCM.
We're going to try to find some people who have these carts to get them read so the ADPCM encoded format can be understood. That way we have more accurate NES ROMs of these games and the ability to use this additional expansion audio chip.
This could also keep the development of NES/Famicom emulation/composing relatively fresh so we don't run out of things to do. :P
