Date   : Sat, 03 Jun 2006 11:33:04
From   : Pete Turnbull <pete@...>
Subject: Re: Cheese Wedge Dating

On Jun 3 2006, 11:10, Joel Rowbottom wrote:
> At 10:55 03/06/2006, Pete Turnbull wrote:
>
> >No, it wasn't a standard modem.  It used the standard tones for
> >1200/75, of course, but it was a unique design, with some rather
> >idiosyncratic (and sometimes problematic) control circuitry.
>
> I can't actually think of a practical reason it would be like this,
> unless it was using signalling to do autodial or something similar to
> the Demon-2 and Designer modems. But the Prestel wedge wasn't
autodial was it?

Of course it was.  It could do quite a lot of things, including (I
think) autoanswer.  It could certainly do autodial and autologin, and
much more besides.  The firmware could store directories of places to
dial, along with login details, and commands to execute, eg to get to a
particular page or start a download or upload.  The easiest way to do
that was to make a local viewdata page on disk, with a menu, and embed
the commands as hidden text or key definitions.

All this meant that the modem had several hardware "states", eg
offline, dialling, waiting for carrier, online, hanging up, and a few
others.  All controlled by sequences of pulses on the RTS line!


--
Pete                                            Peter Turnbull
						 Network Manager
						 University of York