9 Nov
2014
9 Nov
'14
5:29 p.m.
Mouse <mouse at Rodents-Montreal.ORG> skrev: (9 november 2014 23:38:16 CET)
Meh. Auto baud detection has been around a long time. Easy to with uarts as well. I think
all DEC OSes can do it. You basically just set a fairly high speed on the port and read.
You get a character and have a lookup table for the different speeds. That table is
populated by sending in CR at the different speeds and pick the results.
8N1 would actually be the same as 7S1, but depending on the software many variants could
work.
7O will set the high bit for some characters.
Update (computer club) used to have a Votrax, which I had hooked up to a pdp-11. We should
still have it, as well as the manual somwhere.
Johnny
--
Skickat fr?n min Android-telefon med K-9 E-post. Urs?kta min f?ordighet.
> 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.