9 Nov
2014
9 Nov
'14
2:38 p.m.
> With no UART, I guess it bit-bangs the serial
protocol (I am
> surprised there's no CDP1854 on the board). [...]
Well, going by the doc which Francis posted, it
expects a
carriage-return character to be sent by the controlling device at
power-up, and it automagically adjusts the baud rate. I'm a little
skeptical about that (because hard configuration of line parameters
is typical with serial hardware), but I don't know enough about RS232
comms to say how plausible/reliable it is.
If it's bit-banged, I find it plausible; taking a highly oversampled CR
character and deducing the effective divisor from it is relatively
easy.
What the docs don't state is the other expected
line parameters -
data bits, parity, stop bits, so I'm completely in the dark there.
Back in the '80s, I played with a Votrax-branded speech synth. Based
on rather fuzzy memory from that, you want 8N1 or 701 - IIRC the
protocol stuck to ASCII, in which case 8N and 70 are equivalent.
Unfortunately all I can recall of the protocol - even assuming it's the
same on the device I used as on the device at hand here - is that it
used short sequences (two? three? octets) to specify various phonemes,
with conversion, if any, from spelling to phonemes happening on the
host.
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