Date   : Mon, 25 Jan 2021 18:37:37 +0000
From   : robert@... (Rob)
Subject: Completely expanded "Cheese wedge" BBC Micro - just

I could probably do three cheese wedges at the same time - 6502, Teletext
and Prestel Adapters.  On a Master (with internal co-pro), this would be
quite a wide beast... I'd have to clear quite a lot of stuff off my desk!

There's a fairly wide setup in this Acorn advert -
https://www.youtube.com/watch?v=H6EOFwK0yCg

Rob

On Mon, 25 Jan 2021@..., Jessica Rowbottom <jess@...> wrote:

> There were a few other modems which did this sort of thing - the Dacom
> Demon II and Designer modems were step-signalled as well, ISTR.
>
> > On 25 Jan 2021,@18:02, Pete Turnbull <pete@...>
> wrote:
> >
> > On 25/01/2021 14:16, Chris Johns wrote:
> >> I had rather expected the prestel adapter to be not much more than a
> >> modem in a cheese wedge. Was there more to it than that?
> >
> > It has an autodialer.  However the mandate was to build a simple dumb
> > modem without any sort of processor, so it had to use a state machine to
> > change modes and do things like going on/off-hook, dialling, etc.
> > Unlike devices such as Hayes Smartmodems which use an ASCII command set
> > to control smart functions, or other modems that use the user port or
> > some other signalling interface for control, only the Tx, Rx, RTS and
> > CTS lines from the RS423 interface were available to control it.
> >
> > --
> > Pete
> > Pete Turnbull
> >
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