Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ncar!mephisto!udel!gvlv2!faatcrl!jimb
From: jimb@faatcrl.UUCP (Jim Burwell)
Newsgroups: comp.dcom.modems
Subject: Re: HST's vs. Telebits (was Searching for inexpensive V.32...)
Message-ID: <1319@faatcrl.UUCP>
Date: 12 Apr 90 22:39:23 GMT
References: <1438@mindlink.UUCP> <139@dynasys.UUCP>
Organization: FAA Technical Center, Atlantic City NJ
Lines: 62

jessea@dynasys.UUCP (Jesse W. Asher) writes:

>In article <1438@mindlink.UUCP> a186@mindlink.UUCP (Harvey Taylor) writes:
>>In <134@dynasys.UUCP>, jessea@dynasys.UUCP (Jesse W. Asher) writes:
>>} The number of _unix_ sites running HSTs vs. running Telebits are
>>} negligible.
>> Jesse,
>>     Can you document this? I tried to get this kind of info from our
>> sysop, but he says he doesn't have the uucp maps, the only source I
>> know from which to extract such data. The folklore I have heard is that
>> HST has the BBSes, PEP has Unix & Hayes has business, but I have never
>> seen figures for Unix sites (or business). I pulled some data for Fido
>> sites from a local board (see below).

>This is neither scientific or anything else along those lines, but I did the
>following:  I grepped through the uucp maps and found -

>	4 lines referencing "HST" in regard to the modem (there is an HST time
>		zone).
>	5 lines referencing "USR" in regard to the modem.
>		- two of these sites also had Telebits.
>	66 lines referencing "[tT]elebit".

Put us (faatcrl) in for 12 of those Telebits.  We have 12 Telebit T2500s,
which gives us V.32 (9600 baud/full duplex), and PEP (19.2Kbaud/adaptive
duplex).  

Believe me.  Telebit OWNS the Unix market.  This is because they were the only
people to think of marketing a high speed modem which gets good results with
the UUCP 'g' protocol.  To get maximum file transfer throughput from a PEP 
connection when using UUCP 'g', Kermit, Xmodem, and Ymodem, all of which rely
on a full duplex connection, Telebit put "File Transfer Protocol Support" into
it's modems.  You enable this by setting an S register (S111 on a T2500) to
the value for the protocol you'll be using for that call.  The modem detects
when the file transfer starts and "spoofs" the file transfer between the 
computer and the modem, while the two Telebits simply talk PEP between 
themselves (PEP is error correcting, of course).  This allows PEP to allocate 
nearly all if it's channels to outgoing data for the sender, and incoming data 
for the receiver (of course).  Thus, the maxmum throughput of PEP can be 
realized even when using a full duplex file protocol.  If the Telebits didn't 
spoof, the modem would allocate some channels for input, and some for output,
since there is a lot of handshaking going on.  Ymodem wouldn't be THAT bad,
since it only ACKs every 1K block sent.  But 'g', and 'Kermit' (kermit for
the most part) send VERY short (32 to 64 byte) blocks, acks would be coming
back from the receiver very often, and them modem would probably divide the
send/receive channels evenly, thus dropping from almost 19.2KBaud throughput
to 9600 baud throughput!  And since UUCP is locked into using the 'g' protocol,
Telebits are the only answer.  (Too bad it doesn't use a streaming protocol
like Zmodem or something)

I have heard that USR now makes an HST Dual-Standard-U or something for Unix
systems, which also has 'g' spoofing (not sure about Kermit or [XY]modem). 
But even then, I probably wouldn't buy a HST, since they're not nearly as
good on noisy/bad phone lines as the Telebits under PEP (PEPs a trooper on
noisy lines!).  And we have some noisy lines here.  :-)  Owell.  I'll stop now.

C'ya,
Jim
-- 
James S. Burwell
UUCP:  ...!rutgers!faatcrl!jimb        Internet:  jimb@faatcrl.UUCP
"Idiots... " - Anonymous