Pacific Educational Systems VPU-1 External Voice Synth

Michael B. Brutman mbbrutman-cctalk at
Sun Mar 6 22:10:29 CST 2011

On 3/6/2011 8:56 PM, Fred Cisin wrote:
> 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.

Luck and some digging around has turned up information faster than 
usual.  Somebody I knew from PCjr experience was working with this same 
box recently, adding support to MESS (Multiple Emulator Super System). 
And he pointed me at somebody's blog where they discussed all of the 
short comings of the device, and even provide a better ROM for the 
microcontroller to help the flow control.

So I'm happy for a bit, and now I'm going to learn about LPC encoding ...


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