24 Feb
2003
24 Feb
'03
10:31 a.m.
> Wasn't that chip used in the Tandy TRS-80
Model 100 machines.
I thought the M100 uses the 14412 chip...
Yep, You are right.
>
> I remember playing with the Band Pass filters to convince the
>TRS-80 to work
> with CCITT tones, instaed of the Bell tones that were used in
>USA. That was a while ago
IIRC, the 14412 didn't demodulate CCITT tones
reliably at 300 baud. The
better-designed UK modems that used this chip at all used it for the
modulator only and used something like an XR2211 for the demodulator.
Ahh, That explains why it was allways fussy about signal levels. The data
sheet said that it could do it, and I had to alter the level of the
BELL/CCITT pin.
- doug
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