Date   : Mon, 02 Aug 1993 13:07:38 +1200
From   : David Andrew Sainty <David.Sainty@...>
Subject: Synchronous modem emulation

I've just got the chip I needed to make the BBC emulate MNP4 and V.42!
[Only took a couple of months! :-( ]

MNP2 is already going over the RS423 port, so the software side is
basically done. What I may do is just design the hardware, and get MNP4
going. I still don't have all the info on V.42bis, and I have NO info
on MNP5, but MNP4 is definately worth having (More speed PLUS no line
noise!). Also, a lot of modems no longer support MNP2, so relying on
the RS423 by itself dosen't work too well.

This is a significantly cheaper way to go than buying a new modem! (In
fact, it's better than most MNP emulations on top of a 2400bps modem,
my emulation always has to step DOWN to the level of the modem it's
communicating with!)

Once it's going, I'll release another version of Tequilacomm, and info
on how to build the hardware side... (Dual serial ports, Z8530 based, hung
off the 1MHz bus), and those who are still using their beebs as a
terminal can laugh at the poor IBM users forking out their money for
MNP modems! :-)

It may be a while after than that I get V.42bis going (LAPM error correction
will be a breeze, but without the compression it'll be relatively useless,
just use MNP4).

Hope this is useful to people. If you still want to use another machine as
a terminal but would like your modem to be MNP/V.42 capable, I may be
willing to throw something together so the BBC sits between your modem
and other machine converting the signal.....

Dave.