16 Jun
2004
16 Jun
'04
11 a.m.
At 00:25 16/06/2004, Tony Duell wrote:
That's a Modem 2B. I have a pair of those too. Years ago I designed a
dialer (pulsing DTR) and autoanswer add-on for it. The 300 baud ones do
CCITT originate and answere tones, BTW.
Somewhere (and Bletchley are NOT GETTING IT), I
have a Plessey modem (all
discrete components in the GPO case that's about 14" square and 6" high)
that doess 1200 baud transmit, 75 receive. Sounds like a viewdata host
unit to me...
I used to have something one like this, but a 300 baud one. Hige case, drop down front panel with a GPO logo on it,
individual cards mounted
inside for each function. I used to sit my first BBS BBC micro on top of it!
One of mine has a GPO logo, the other a BT nameplate :-). Identical
inside.
These modems (both the 300 buad and the 1200/75 baud ones) have 4 modules
inside. Power supply, Modulator, Demodulator, Control. All discrete
transistors, relays, pot-core coils, etc.
Somewhere I have a Modem 13A. This is a plinth that mounts under a
standard type 746 telephone (which has a couple of swtiches added for
voice and data) which contians a 300 baud modem.
For the life of me I can't remember what happened to it.. This was about
1982, and it was my first modem. I later upgraded to a Maplin
build-your-own modem kit, before getting one of the early Pace Nightingale
I think I still have some bare, never soldered, PCBs for the Maplin modem...
-tony