Netronics Phoneme generator info

Johnny Billquist bqt at
Mon Nov 10 14:25:06 CST 2014

On 2014-11-10 18:28, Mouse wrote:
>>>> [...CR for autobaud...]
>>> 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.
>> 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.
> As described, this can't work if the sender's speed is slower than 1/10
> of the receiver's speed, because then the receiver's entire character
> time falls within the sender's start bit.  (Of course, that's enough to
> span a factor of 8, which is enough to be somewhat useful; it allows
> autobauding from 9600 down as low as 1200, for example: 0x0d=N,
> 0xe6=N/2, 0x78 with a framing error = N/4, 0x80=N/8, 0x00 with a
> framing error = N/10 or slower.)
> Handling faster speeds is more difficult, and may vary based on details
> such as whether the sender's speed is slightly more or slightly less
> than (say) double the receiver's speed.

True. There are limits. DEC seems to have been fond of using 4800 for 
the initial sampling. That worked for anything between 600 and 9600 at 
least. Which I'm sure is all a Votrax could handle as well.
(The DEC code does a second sampling at 300 bps if they didn't 
successfully detect things at 4800.)

> But, if it's bit-banged, then simply greatly oversampling the autobaud
> input can allow autobauding even to unusual speeds like 4000 baud,
> provided they're within range.

Yes, with high enough samplig, and long enough, you can always figure it 
out. Even for odd speeds and so on... :-)

>>> [...] ASCII, in which case 8N and 70 are equivalent.
>> 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.
> I said 701, not 7O1.  I initially wrote 7Z1, but its converse is
> ambiguous (because "one" and "odd" both begin with o).  I didn't think
> of M and S; I wish I had, because the set M S E O is less likely to
> display ambiguously than 0 1 E O.

Ok. Color me stupid. :-)
I really didn't notice you typed a zero, and just read it as 'odd'.
(I need to read text with a better font, that makes zero and o differ 


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