interactive (host=>PC) data compression wanted

[J Q Johnson]

People using a terminal emulator on home computer with a modem soon
find that 1200b or 2400b isn't all that fast.  In principal, effective
data rates for typical interactive terminal sessions could be improved
by at least a factor of 2 or 3 using data compression techniques.

Does anyone have software for such host=>terminal data compression?
Easy static techniques exist for 20% to 50% improvements; can we do
better?  Note that in addition to being self-synchronizing or reliable
(to cope with modem transmission failures) any such technique must not
be too costly to either encode or decode.  Note also that various
vendors have quite efficent proprietary implementations.

My particular environment is a 4.xBSD host and an ATT 3b2 (sys V) or
IBM PC (running DOS or Xenix) client, talking at 1200b asynch 7 bit
with XON/XOFF.  Ideally I'd like public domain code that supports at
least one of these environments.  Failing that, pointers to algorithms
or publicly available implementations for other environments would also
be appreciated.

Given sufficient feedback, I will of course summarize.

cornell!jqj		UUCP
jqj at cornell.arpa	Internet