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From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: Ensoniq Chip and Video sound production
Message-ID: <1991Apr12.203139.21362@nntp-server.caltech.edu>
Date: 12 Apr 91 20:31:39 GMT
References: <70615@eerie.acsu.Buffalo.EDU>
Organization: California Institute of Technology, Pasadena
Lines: 26

v097pba8@ubvmsd.cc.buffalo.edu (Ken F Morton) writes:

>	I think I've asked this before, but what is the playback resolution
>of the ensoniq chip?  I think it is 8bit, but I'm hoping I'm wrong.  Any
>software tricks to make the output psuedo-16 bit (like sampling at 16 and the
>messing with more than one sound generator pair...).

Here's the deal: 32 oscillators, each reads 8 bit sound data and pumps it
through its own 8-bit volume setting. You could fake 15 bit sound by having
7 oscillators with powers of 2 in their volume settings, and updating them
REALLY FAST. I'd have to look at it a bit more but I don't think you can
do it without sucking up all of the CPU time while the sound is playing --
sorta like 3200 color pictures.

>oh yeah, is it possible to de-multiplex more than two channels of sound
>from the GS?  I think I read somewhere that it is possible...

Sure, the DOC supports 16 but Apple's connector on the motherboard only
supports 8 (big deal, the stereo cards only use 2). What happens is a
binary channel number shows up with a clock signal, and you are supposed
to Sample&Hold the analog output into the specified channel as long as you
can (never more than 38 uS if a sound is playing). There was a card that
did 8 outputs, but I never saw it advertised anywhere.

Todd Whitesel
toddpw @ tybalt.caltech.edu