POKEY 4-bit sampling and 7800basic

[Synthpopalooza]

A little known POKEY trick:

 

Writing $10-$1F rapidly to one of the AUDCx registers will cause POKEY to replay 4-bit audio samples.  Downside of this is it takes 100% CPU.

 

Now here's the hard part ... I believe I can down sample to 4-bit audio using Audacity.  How then would I include this data into 7800basic, i.e. read data and convert to 4-bit values to be written as follows:  psound 0,0,1,x ... where x is $00 to $0F

 

I know 5200 Berserk does this trick for the robot voices, though the game stops while doing so.

[+Stephen]

Can't answer this directly, but there are now timer techniques used (see Space Harrier), that allow full digi playback without blanking the screen, nor stopping the action.

[RevEng]

TIA has the exact same trick, with identical resolution. No need to require a pokey for playing samples.

 

I haven't done this yet in my own code, but Bob has done it a few times. You'd need to use assembly code within 7800basic to update the register, to play the sample.

[Synthpopalooza]

I'll have to look at the code then.  This ties into the Kung Fu Master thing in another thread a little ... but I wanted to experiment too.