Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!ucsd!hub.ucsb.edu!tom
From: tom@bears.ucsb.edu (Tom Weinstein)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Differences between HST and V42
Message-ID: <7435@hub.ucsb.edu>
Date: 27 Nov 90 23:42:43 GMT
References: <11623@milton.u.washington.edu> <1990Nov26.031104.8597@xrtll.uucp>
Sender: news@hub.ucsb.edu
Reply-To: tom@bears.ucsb.edu
Organization: Silicon Graphics Inc.
Lines: 41
In-reply-to: silver@xrtll.uucp's message of 26 Nov 90 03:11:04 GMT

Well, since I looked at the new USR modems at Comdex, I guess I should
say something about this.

In article <1990Nov26.031104.8597@xrtll.uucp>, silver@xrtll.uucp (Hi Ho Silver) writes:
>    HST (High Speed Transfer ... or is it Transmission?) is USRobotics'
> proprietary modulation scheme to achieve higher-than-2400 bps throughput.
> It goes up to 14.4 kbps, and was devised back in the days when there wasn't
> even a 9600 bps international standard.  If you buy the USR HST modem,
> you'll be able to communicate at 14.4 kpbs with another USR HST modem, but
> only at 2400 bps with other manufacturers' modems.  Also, this is an
> asymmetrical protocol - while there is a channel in one direction running
> at 14.4 kbps, the return channel runs only at 450 bps.  For many users,
> this is not a problem (downloads from a BBS or remote control of a PC,
> for example, are largely one-way transfers).  However, if you're using
> it to do UUCP between Unix boxes, you'll get terrible throughput since
> the 450 bps channel won't satisfy the protocol.

[ ... ]

>    Actually, USR has three modems.  They have a V.32 modem which uses the
> standard V.32 modulation techniques to achieve 9600 bps communications.
> They have an HST modem which uses their proprietary HST modulation to
> achieve 14.4kbps communications.  They also have a Dual Standard modem which
> will use either.

The USR Courier HST Dual Standard modem has two high speed modes.  One
is symmetric and goes at 14.4 kbps BOTH ways.  The other is asymmetric
and goes at 38.4 kbps one way and 450 bps the other.  Another nice thing
about it is that is monitors the line quality and slows down if the
quality gets poor.  Lots of modems do that, but the USR speeds up again
if the quality gets better which I don't believe anyone else does.

The Dual Standard also supports V.32bis and V.42bis.

USR also has two other modems that are each one half of the Dual
Standard.  One supports the HST standard and the other does V.32bis and
V.42bis.

--
He is Bob...eager for fun.         | Tom Weinstein  tom@bears.ucsb.edu
He wears a smile... Everybody run! |                tweinst@polyslo.calpoly.edu