From: almesber@nessie.cs.id.ethz.ch (Werner Almesberger) Subject: Re: Serial communications problems Date: Sun, 13 Dec 1992 04:34:23 GMT
In article <1992Dec13.021248.3074@athena.mit.edu> tytso@ATHENA.MIT.EDU (Theodore Ts'o) writes:
> It would be possible to write a serial driver that did not use
> interrupts --- by hooking something to the timer interrupt and having it
> check 100 times a second to see if there's anything on the serial port;
> but it would ruin your system performance, and it wouldn't really work
> unless you had a 16550A UART, or if you aren't doing anything faster
> than 600 bps. (And even if you had a 16550A, you wouldn't be able to do
> anything faster than 9600.)
You're a bit too pessimistic here. I'm using such a driver to run all
four COM ports and it does 2400 bps with a 16450 and 19200 bps with a
16550A. 19200 bps gets a bit unreliable under load, but it's still
acceptable for Zmodem. I'm polling at 300 Hz and it doesn't lower
system performance very noticeably.
- Werner
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