Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!europa.asd.contel.com!seka.scc.com!enger
From: enger@seka.scc.com (Robert M. Enger)
Newsgroups: comp.dcom.modems
Subject: Re: Why no PC modems without UART (re: Beware the Telebit T18pc)
Keywords: uart chip emulation modem
Message-ID: <1991Feb10.203043.372@europa.asd.contel.com>
Date: 11 Feb 91 01:30:43 GMT
References: <1991Feb9.022024.10932@wsrcc.com> <23314@netcom.COM> <1991Feb9.164603.17731@europa.asd.contel.com> <23490@netcom.COM>
Reply-To: enger@seka.scc.com
Organization: CONTEL Federal Systems
Lines: 29
Nntp-Posting-Host: seka.scc.com

Greg:

There has been some discussion on this list lately regarding the
failings of the UART chips used on some modems.  One person commented
that even the famous T2500 used such and such unacceptable UART chip.
Obviating UART chips altogether might be valued by some customers.

Another advantage might be speed.  While simple minded operating systems
might not have much else to do (might not be able to do much else) when
the telecom program is running, some of the fancier OSs do.  Thus, a
board that reduced the interrupt load on the host might be valued because
it would conserve system resources so that they could be devoted to 
other processes..

Even on a simple minded OS, if one's communications program is trying
to do some form of end-to-end integrity check (host to host checksum, etc)
then the time saved by not having to service per-character I/O interrupts
may provide a faster end-to-end throughput, especially on lower-powered CPUs.

I hope this doesn't devolve into a range war.  I have no bone to pick.
I don't even own a computer.  I dial in from a dumb terminal at home :-)

Bob

-- 

Robert M. Enger
CONTEL Federal Systems
enger@seka.scc.com  (Internet)