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Mercury Unit v3

Started by hoshikawa, December 15, 2018, 09:46:11 pm

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hoshikawa

December 15, 2018, 09:46:11 pm Last Edit: December 16, 2018, 02:56:11 am by hoshikawa
I got one, complete with optical output chip. aside from loading pcm8a is there anything else i need to run this on an XVI? how do i set it up?

neko68k

AFAIK MercuryUnit uses PCM8pp. There is also a driver that patches the IOCS ADPCM functions to use the MercuryUnit instead of the OKI. ZMusic games should work if you replace the PCM driver (I think PCM8pp supports MPCM which is required for ZMusic mixed PCM IIRC). Similarly, games that either use PCM8 already or are patched to use it can work if you use PCM8pp.

All that said, the MercuryUnit is pretty slow to use. The driver will 1) decompress the samples to mix 2) mix them 3) DMA (probably) 44khz audio to the IO slot. Even going from 15khz to 31khz on the OKI is too expensive for 10mhz and might be too much to run a game also at 15 though I'd have to check to be sure. For example, the PCM8 patched version of Street Fighter 2 is unplayable at 10mhz and has some raster effect wonkyness still at 15mhz and that's just doing 3 or 4 samples. The fact is that a lot of games don't even use 15khz OKI mode and use 8 or 4 instead. For performance reasons.

hoshikawa

thanks for the info, i'd like to at least make sure it works. how do i test it out?

neko68k

Load this up instead of whatever PCM driver you have for music. If you're using the V4 games disk I think it loads RDN or PCM8A, just swap that with PCM8PP.

PCM8PP