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From: chris@mimsy.umd.edu (Chris Torek)
Newsgroups: comp.unix.aux
Subject: Re: Keeping up with 19200 baud
Message-ID: <20978@mimsy.umd.edu>
Date: 28 Nov 89 22:58:54 GMT
References: <1219@smurf.ira.uka.de> <568@panix.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 15

In article <568@panix.UUCP> alexis@panix.UUCP (Alexis Rosen) writes:
>This is not my field of expertise, but I believe that the Mac's built-in
>serial ports can't begin to cope with 19.2kbps because they get an interrupt
>for every byte.

It is possible to keep up with 1920 characters per second even with one
interrupt per character, *provided* that the interrupt handler is carefully
hand-coded, or the CPU is extremely fast.  The average 68010 with the
average sloppy `do a few thousand instructions' style interrupt handler
will not keep up.  A somewhat slow 68020 Unix box (the Sun 3/50) with
a reasonably good interrupt handler (i.e., not SunOS 4.x) will, although
it will use most of the CPU.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@cs.umd.edu	Path:	uunet!mimsy!chris