Path: utzoo!attcan!uunet!lll-winken!lll-ncis!helios.ee.lbl.gov!pasteur!ucbvax!bloom-beacon!oberon!pollux.usc.edu!papa
From: papa@pollux.usc.edu (Marco Papa)
Newsgroups: comp.sys.amiga
Subject: Re: high-speed file transfer
Message-ID: <14674@oberon.USC.EDU>
Date: 13 Jan 89 19:40:40 GMT
References: <8901131551.AA12559@PTT.LCS.MIT.EDU>
Sender: news@oberon.USC.EDU
Reply-To: papa@pollux.usc.edu (Marco Papa)
Organization: Felsina Software, Los Angeles, CA
Lines: 39

In article <8901131551.AA12559@PTT.LCS.MIT.EDU> atheybey@PTT.LCS.MIT.EDU writes:
|I have tried DNet with the USRobitics HST modems, and have a few
|reservations.  (I ended up deciding that I couldn't afford an HST
|modem, and so did not look for a solution too vigorously.)  The HST
|modems have a *unidirectional* 9600 baud channel.  The two modems
|negotiate which direction gets the high speed channel, based on the
|number of characters in the modems' buffers.  The other direction is
|300 baud.

Yes, that's a problem with the HST and simlilar "uniditectionsl" high-speed
modems.  It is not a problem at all with a "normal" terminal program.

|I do know that other
|people dialing up to the terminal concentrator with the HST modems and
|terminals do achieve rates much closer to 9600 bps (at least fast
|enough that a VT100 can't handle it without flow control :-).

Way, way too fast for a "real" vt100.  The HST will allow transfers of
compressed files with speeds of 1500 char/sec, and transfers of text files
of up to 1800 char/sec or more depending on the file.  The "unidirectionality"
of the HST modem works in its favour with a "normal" communication program.

Characters typed are not bufferred.  Protocols like Zmodem and Ymodem-g
use NO acknowlegment, so one channel is not used unless there is an error.

|If one could permamently assign the high speed channel to the
|Unix--|Amiga direction, I think that DNet would have performed better
|(except for uploads, of course).  I don't know if it is possible with
|this modem.

I'm not sure it can be done, since it is the modem that "dinamycally"
reassigns the high speed channel to either send or receive.  Surely
I could not find an AT-command that allows me to set that.

-- Marco Papa 'Doc'
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