(2) Video Game Sound + Speech ( was RE: 80's Video...)

J.D. McEachin jdm at synthcom.com
Thu Feb 29 07:42:19 CET 1996

On Wed, 28 Feb 1996, Clive Jones wrote:

> Bally first used  the custom 3 channel analogue IC - "AY-3-8910", I've   
> just checked the chip itself and and no manufacture ID is given except   
> for the two *large* letters "G.I.", Bally went on to use another "G.I."   
> chip - the "AY-3-8912"

I have an AY-3-8910 - it's a General Instruments part.  IMO it's not very 
useful for synth-diyers.  The AY-3-8912 is a little more flexible and 
_perhaps_ useful.  I seem to remember a cool looping envelope feature...
> Williams "Defender" series electronics used the 55564 CVSD speech chips,   
> which, I believe are loaded in serial format rather than parallel.

I'm pretty sure the 55564 was a Harris part.  CVSD was a fairly cheap way 
to compress speech, encoding changes in the slope of the signal as a 0 or 
1 in a serial bit stream, depending on whether things were going positive 
or negative.  Low bandwidth - maybe 40-4000Hz, and kinda grungey (and not 
a charming sort of distortion like LPC).  Maybe there are ways of messing 
w/ the digital data that would be cool, but like I said, it's grungey.

Sherman, set the Wayback Machine for 1984, when I designed & built an
Apple II board w/ 4 phone line interfaces, 4 channels of CVSD output, and
4 DTMF encoders/decoders.  If I had marketed it as a telemarketing tool,
I'd be rich.  As it is, it's been used to run a Gay Phone Dating Service
for 24 hours a day, 7 days a week, for 11 years. 

Ob DIY:  I used machine tool sockets in perf board w/ wire-wrap wire 
soldered point to point to construct the board, and it's been totally 
reliable since I tracked down a cold solder joint that started causing 
problems after 4 months.  A useful construction technique if you don't 
want to layout a pcb...


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