"Paul B. Webster VK2BZC" writes:
>  Ahh yes, but that was Votrax.  Was it completely encapsulated in epoxy
>resin to make it un-repairable, like the Type-n'-Talk?  I think I have
>two of these, but at least one was faulty.  They used a serial interface
>which also had handshake problems.

        That's the beast, all right.  They were very protective of their
circuitry and design, (Insert philosophical rant and %#@@%%%&&*** here.)

        I believe this device sold for about $400.00 when new.  I bought
it used about 12 years ago and I will try to use it until it dies and then
that's that.  The power switch also resets the Z-80 so you have to keep the
switch clean and make several attempts at powering it up.  This also means
that one must cycle the power switch off and on if the power is interrupted
from the AC outlet such as an external outlet strip or power failure.
A little less potting compound and a better reset circuit would have made
a pretty good product for the time.


>

        Excellent description of the strobe/ACK timing dropped for brevity.
I connected another odd-ball speech synthesizer to an Apple II parallel port
in 1979 and basically discovered what you told us the hard way.  I even
put a fast-forward button on the box to let one move through the output
at a fast rate.  All that did was to take the speech board's Busy output
out of the circuit and cause a one-shot to deliver an ACK for each strobe
sent.  The speech board used, then, was a TeleSensory Minispeech2 module.
It used -5 and -15 volt power rails and logic levels were -5 for 0 and 0 for
1.  The company had good documentation for it and it explained what to do
to properly interface it with TTL.  The Minispeech board also had only
6 data lines so you had to logically prevent control characters from reaching
the data bus or you would hear lots of weird characters mixed in with the
proper data.

        I shouldn't tell this part, but I got confused back in 1979 about
which data bit was LSB and MSB and soldered all 8 data lines wrong-way
out.  I got the strobe and other lines of which there were only one correct,
so I got output, but it was all garbage.  I remember being shall we say
furious when I found out about the reversed conductors on the data lines
because they were all tiny stranded wires that had been a royal pain to solder
in the first place.

        Some of these discussions bring back floods of memories, but I won't
waste any more of the list bandwidth.  I am glad I finally decided to just
buy an 8-bit input port for the application that started all this good
discussion.  I am even more surprised that somebody is still selling them.

        The system board I am trying to get screen dumps from to work the
CMOS setup is the system I plan to use for PIC development so this will
eventually lead to on-topic messages:-).

Martin McCormick