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From: BILLW@sri-kl@sri-unix.UUCP
Newsgroups: net.micro
Subject: Re: quadram boards
Message-ID: <4725@sri-arpa.UUCP>
Date: Tue, 30-Aug-83 21:56:00 EDT
Article-I.D.: sri-arpa.4725
Posted: Tue Aug 30 21:56:00 1983
Date-Received: Sat, 3-Sep-83 08:15:01 EDT
Lines: 13

Some boards do not enable interupts for the second rs232 port.  I
tried this out as I was developing a (comercial) communications
package for the IBM PC, and found that the interupt pin on the
second 8250 on a (argh! cant remember the company name.  It was
a 256K memory + 2 serial port board) wasnt connected to ANYTHING!

The reasoning behind this (I assume) is that if you have multiple
chips generating a single interupt, then you cant trivially figure
out which port the interupt was actually for.  In particular,
interupt driven software that assumes only one active port is
likely to break.

Bill Westfield