Pacific Educational Systems VPU-1 External Voice Synth

Fred Cisin cisin at
Sun Mar 6 20:56:22 CST 2011

On Sun, 6 Mar 2011, Michael B. Brutman wrote:
> This is an external voice synthesis box based on an Intel 8031
> micro-controller and a TSP5220CNL synthesis chip.  It has an RS232
> interface, volume and tone knobs, a headphone jack and an RCA jack for
> external audio.
> Does anybody remember these things and how to talk to them?  I've tried
> all of the various bps rate and parity combinations from 300 to 19200
> and I can't get anything response (data or sound).

I don't remember anything useful.  Usually.
I remember connecting a serial voice output unit to a TRS80 model 2, at
the request of a Radio Shack "Computer Center".  They gave me a Model 2
Technical Reference Manual (in addition to my invoice) for doing it!  The
part that is relevant is that it required, for it's handshaking, a jumper
on a DB25 connector that was NOT pins 1 through 8 or 20.  It may have been
10, 12, or 22, none of which made any sense to me at the time, but that is
what that peripheral demanded.

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