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From: jc58+@andrew.cmu.edu (Johnny J. Chin)
Newsgroups: comp.os.msdos.programmer
Subject: Re: COM1 COM2 interrupt numbers?
Message-ID: <Iaw_cB600VY6IMyqUW@andrew.cmu.edu>
Date: 14 Sep 90 09:59:41 GMT
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 33

First of all ... the hardware interrupt for the serial ports are 3 or 4, by
default.

COM1 - IRQ4 (hardware interrupt request #4)
COM2 - IRQ3

As for some other common ones:

INT 0 - NMI (non-maskable interrupt) - usually due to memory parity error
INT 1 - reserved
INT 2 - used by many EGA/VGA cards (usually available on 8088)
        cascading interrupt on 286/386/486 machines
INT 3 - COM2:
INT 4 - COM1:
INT 5 - Hard Disk Controller on 8088 (available for LPT2: on 286/386/486)
INT 6 - Floppy Controller
INT 7 - LPT1:

INT 14 - cascaded off INT 2 - Hard Disk Controller on 286/386/486.


I hope this information helps ...

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Disclaimer:   The views expressed herein are STRICTLY my own, and not CMU's.