Prestel (Was: Re: What is this??? - Update)

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Jun 16 18:00:17 2004

>
> At 00:25 16/06/2004, Tony Duell wrote:
>
>
> >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,

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.

> 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
Received on Wed Jun 16 2004 - 18:00:17 BST