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From: urlichs@smurf.sub.org (Matthias Urlichs)
Newsgroups: comp.dcom.modems
Subject: Re: Why no PC modems without UART (re: Beware the Telebit T18pc)
Keywords: uart chip emulation modem
Message-ID: <6v#qh2.o+3@smurf.sub.org>
Date: 9 Feb 91 18:49:06 GMT
References: <1991Feb7.225401.28138@ingres.Ingres.COM> <1991Feb9.022024.10932@wsrcc.com> <23314@netcom.COM>
Organization: University of Karlsruhe, FRG
Lines: 22

In comp.dcom.modems, article <23314@netcom.COM>,
  gandrews@netcom.COM (Greg Andrews) writes:
< 
< Ever try to emulate a UART chip in software?  Ever wonder why the smart
< multiport boards don't do it either?  It's a pain in the butt!
< 
However, when you know what's on the other side of the pseudo-UART (a Telebit
modem, in this case), you can forget about almost every feature.
All you need is bits&parity (baud rate for the "use speed of last AT command"
modes only), handshake lines, and send+receive buffer.

Seems reasonable to me.

However, it still has to be implemented&programmed&tested, and it might be
more cost-effective to just stick two cheapo UARTs (one for the PC, and one
for the modem -- you already have the software for the latter from your
standalone modem PROMs) onto the board instead of the latches you'd otherwise
need.

-- 
Matthias Urlichs -- urlichs@smurf.sub.org -- urlichs@smurf.ira.uka.de     /(o\
Humboldtstrasse 7 - 7500 Karlsruhe 1 - FRG -- +49+721+621127(0700-2330)   \o)/