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From: kjeld@iesd.dk (Kjeld Flarup)
Newsgroups: comp.sys.ibm.pc
Subject: Two Reply's: HW interrupts and COM port's
Message-ID: <2073@iesd.dk>
Date: 15 Jun 89 11:50:27 GMT
Reply-To: kjeld@iesd.dk (Kjeld Flarup)
Organization: Dept. of Comp. Sci., Aalborg University, Denmark
Lines: 44

I have noted some questions concerning interrupts and COM ports.
First there is a reply to Dave Vasko:
		PORT    ADDRESS      INTERRUPT 
		COM1	3F8-3FF      IRQ4
		COM2	2F8-2FF      IRQ3
		COM3    2F0-2F7      IRQ4 ( or IRQ2 )
		COM4    3F0-3F7      IRQ3 ( or IRQ5 )

I think. because noone seems to know for sure.
Let's look at the HW interrupt list Jonatan Vail wasn't sure about.

   IRQ  0 - Timer.
   IRQ  1 - Keyboard.
   IRQ  2 - EGA vertical retrace.
   IRQ  3 - COM2.
   IRQ  4 - COM1.
   IRQ  5 - Fixed disk.
   IRQ  6 - Diskette.
   IRQ  7 - LPT1.
   IRQ  8 - Real time clock.
   IRQ  9 - LAN adapter 1.
   IRQ 10 - Reserved.
   IRQ 11 - Reserved.
   IRQ 12 - Mouse.
   IRQ 13 - Coprocessor.
   IRQ 14 - Fixed Disk.
   IRQ 15 - Reserved.

It also occurs to me that something is wrong.
I know that internal modems can be placed almost anywhere. Therefore Procomm
Plus gives the user a free selection of port adress and interrupt number.

Timo Salmi had some troubles with his modem at COM3, and at the same time using
COM1. When I first Installed my modem it only took me 15 minutes to put it in.
And 1 hour 45 minutes to remove my mouse driver. Because these used the same
interrupt. See my table above.

If one wants to run three or more COM ports at one time by independent
software drivers. I can be nessecary to use individula interrupts for each
of them.

-- 
Kjeld Flarup Christensen | "I'am now thirty-seven times older than the universe
kjeld@iesd.dk            | itself." Marvin the depressed Robot.