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From: gil@limbic.ssdl.com (Gil Kloepfer Jr.)
Newsgroups: comp.unix.sysv386
Subject: Re: internal Telebit, SCO Unix 3.2, 80 bytes/sec???
Summary: 16450
Message-ID: <130@limbic.ssdl.com>
Date: 4 Jan 91 06:44:25 GMT
References: <24558@dime.cs.umass.edu>
Organization: Southwest Systems Development Labs, Houston, TX
Lines: 29

In article <24558@dime.cs.umass.edu> williams@cs.umass.edu writes:
>I am calling SCO's sosco system for testing and the Systems entry is
>set to use the dialTBIT dialer with the speed set at 19200.  uutry
>reports CONNECT FAST, but the xferstats shows that I'm only getting
>76 bytes per second on large transfers!

The internal Telebits only have the 16450 UARTs in them, so you would
need to unsolder the 16450 and replace it with a 16550 in order to
really get good performance, even with FAS.  I had a friend who did
this, and now the thing flies.

Note though that you also may need to perform a procedure to turn
hardware flow control on (I think even the internal telebit supports
this internally).  If this doesn't help, then you'll need to do the
UART replacement.  I don't recommend it to the meek or someone who
thinks that they can do fine soldering with a 100W soldering gun :-)

A fix that usually works (but is less than satisfactory when you
consider the price of the modem) is to reduce the speed to 9600 baud.
This will generally clear-up the overrun problems associated with
the packet loss (which is why your throughput is so bad).

Why Telebit didn't use 16550s on that modem beats the heck out of me ...

-- 
Gil Kloepfer, Jr.              gil@limbic.ssdl.com   ...!ames!limbic!gil 
Southwest Systems Development Labs (Div of ICUS)   Houston, Texas
"There are beautiful people I wish would have never opened their mouths,
because such ugliness oozes out."  Philosophy Prof. at NYIT