What's the difference between the Core Grafx and Core Grafx II?

[Bonknuts]

There's an audio upgrade (revision 6280A) in one of the CoreGrafx models over the original PCE. I believe it's the CoreGrafx model 1 because it came out about the same time as the SGX (which has the upgraded revision). So it's possible that CGII doesn't have this (I've never seen a Duo model with the A revision cpu). So that's a potential, albeit small, difference.

[Necromancer]

There's an audio upgrade (revision 6280A) in one of the CoreGrafx models over the original PCE.

What does it do differently/better?

[Bonknuts]

There's an audio upgrade (revision 6280A) in one of the CoreGrafx models over the original PCE.

What does it do differently/better?

 There's popping on the corresponding channel's DAC when volume is adjusted. It's relative to the size of the adjustment, but it can get pretty loud/noticeable if the change is large (in either direction, including turning 'off' the channel). So the revision cpu fixes this (since the audio chip is included in the same package as the cpu) and gives a little smoother audio. When I was creating a few different sound engines, I specifically wrote support for silencing a channel without the noticeable pop. So you can work around it if you're making your own sound engine/code. The one offender that stood out to me was Ninja Spirit (more apparent with headphones). Trust me, you don't want to notice it or you'll start hearing in other games/musics as well. Ignorance is bliss

[spenoza]

If you have a decent selection of hardware at home, could you check out this popping for us? I have a Core I, but that's it. I can't do any sort of comparison. It is also possible that the revision was incorporated into later CPUs without the model number change.

[Necromancer]

Trust me, you don't want to notice it or you'll start hearing in other games/musics as well. Ignorance is bliss

Nope, mine doesn't make any untoward noises.  *sticks head in sand* 

[Bonknuts]

If you have a decent selection of hardware at home, could you check out this popping for us? I have a Core I, but that's it. I can't do any sort of comparison. It is also possible that the revision was incorporated into later CPUs without the model number change.

 I only have a white pce, supergrafx, and an original US duo. I did a bunch of test along with mednafen emulation author and the result is a selectable core for pce audio emulation (it emulates the pops and some of the other small behavior. The waveform output is inverted on the A revision too, but that could just be the amp circuit in general - but it does have a small impact when CD and ADPCM is accompanied with it. And other tiny small differences). We did a ton of testing, so I don't think there's anything else really to be found (but I encourage anyone to take up the task. The more tests, the better). There's somethings you can do on the A revision that you can't do exactly on the original revision, like streaming high playback sample rates and low cpu resouce - using the waveform memory as a small buffer. The original audio chip would allow this, but turning on/off the channel causes a LOUD buzzing sound. The original chip can use a work around by having another channel cause a reverse direction audio spike to cancel it out but it requires two channels to do the same trick the SGX using one. Though I digress, 'cause no games do this...