From: "Louis J. LaBash, Jr." <A200%SIUEMUS.BITNET@mitvma.mit.edu> Subject: Re: Modems and IRQ's (again) Date: Wed, 28 Oct 1992 21:11:25 GMT
On the PC-AT platform IRQ priorities start with #0 and go to #15,
with #0 (Timer Click) having the highest priority. Therefore, IRQ3
(COM2 & COM4) has a higher priority than IRQ4 (COM1 & COM3).
High speed MODEMS and FAX boards should be configured to use IRQ3
because this hardware can generate a lot of interrupts. I've seen mouses
used on COM2 (DOS applications) causing problems for a MODEM. Personally,
I had a MODEM/FAX board that couldn't receive FAXs when configured to use
COM1 (IRQ4). This board worked Ok on sending FAXs. The vendor's admonition
to use the highest prioity interrupt solved my problem.
It is all a matter of priorities.
-ljl-
---------------------------------------------------------
/* If you drive -reasonable and proper- in the Indy 500
* --you'll loose.
*/
Louis J. LaBash, Jr.
A200@SIUEMUS.BITNET | labashl@vax3.siue.edu