Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!aplcen!uakari.primate.wisc.edu!ames!amelia!izen
From: izen@amelia.nas.nasa.gov (Steven H. Izen)
Newsgroups: comp.unix.i386
Subject: Re: Third serial port
Message-ID: <4300@amelia.nas.nasa.gov>
Date: 20 Dec 89 17:53:36 GMT
References: <12978@cit-vax.Caltech.Edu> <1989Dec19.002448.2979@virtech.uucp> <1989Dec19.220018.18080@ico.isc.com>
Reply-To: izen@cwru.cwru.edu (Steven H. Izen)
Organization: Case Western Reserve University
Lines: 18

In article <1989Dec19.220018.18080@ico.isc.com> rcd@ico.isc.com (Dick Dunn) writes:

>IRQ2 on a PC corresponds to IRQ9 on the AT bus--which includes the 386 ISA
>machines.  By that I mean that the line on the bus which generates an IRQ2
>on a PC generates an IRQ9 on an AT (since, because of the reason Cahill
>points out, it wouldn't make sense to have an IRQ2 bus line).  So, if you
>have a board which is designed to have "IRQ2" as one of its choices,
>selecting that will give you an IRQ9 on an AT-bus machine without further
>ado.

Yes, but if you have a VGA (or EGA) will the vertical retrace interrupt,
which according to TFMs goes on IRQ9, get in the way?

-- 
Steve Izen: {sun,uunet}!cwjcc!skybridge!izen386!steve  / Quote corner:
or steve%izen386.uucp@skybridge.scl.cwru.edu          / 
or izen@cwru.cwru.edu	   /-------------------------/ My second bike is a car.
                           | The problem is that I *was* paying attention.