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From: labc-1ic@e260-1f.berkeley.edu (Willy S. Liao)
Newsgroups: comp.sys.mac.comm
Subject: Re: zmodem and MNP compression
Summary: It does work
Message-ID: <1991Apr29.193312.16542@agate.berkeley.edu>
Date: 29 Apr 91 19:33:12 GMT
References: <1991Apr29.153954.1661@magnus.acs.ohio-state.edu>
Sender: root@agate.berkeley.edu (Charlie Root)
Organization: University of California, Berkeley
Lines: 35

In article <1991Apr29.153954.1661@magnus.acs.ohio-state.edu> scasterg@magnus.acs.ohio-state.edu (Stuart M Castergine) writes:
>
>I have recently ben testing out an MNP error-correctin gmodem. It
>works great except for the fact that I can't get zmodem protocol to
>work while MNP protocol is in effect.
>
>Consultant here says the two can't co-exist. Is that true?
>I can't seem to get xmodem to work, either.
>
>Is kermit the only protocol that will work in conjuntion with MNP?
>What kind of performance are you getting from it?
>
>-- 
>scasterg@magnus.ircc.ohio-state.edu	Stuart M Castergine
>	"The sound of gunfire off in the distance; I'm getting used to
>	 it now."  -- The Talking Heads, Life During Wartime

Well, I use Zmodem with MNP 5 and it does work, sort of.  I have to watch out
for nasty flow-control problems because the modem I'm connecting to can't
pass on flow-control signals to the UNIX host (so I'm told).  Anyway, with
sz 3.07 I've gotten over 300 cps on text files routinely (I usually use
only MNP 4 when transferring .sit or .cpt files).  If flow control is a
problem on your system, try something like 'sz -w 1536', which means
"do not send more than 1536 bytes unacknowledged" so if your Mac does
something under MultiFinder which hogs the CPU, the UNIX host will stop
sending after 1536 bytes have gone through w/o a reply from your Mac.

Anyway I do recall reading in my modem manual that xmodem absolutely does
not work without XON/XOFF flow control, so this implies it will never work
with MNP 5 & RTS/CTS.  But zmodem I know will work, if you can figure out
how to force it to...  This specifics may also have to do with whether you're
talking to a BSD host or a SysV host, or one that's not even UNIX...

Willy Liao
labc-1ic@web.berkeley.edu