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Path: utzoo!linus!philabs!seismo!hao!hplabs!sri-unix!BILLW@SRI-KL
From: BILLW@SRI-KL@sri-unix.UUCP
Newsgroups: net.micro.pc
Subject: Re: Quadram Serial Ports Problem
Message-ID: <4757@sri-arpa.UUCP>
Date: Tue, 30-Aug-83 21:56:00 EDT
Article-I.D.: sri-arpa.4757
Posted: Tue Aug 30 21:56:00 1983
Date-Received: Sun, 4-Sep-83 22:41:27 EDT
Lines: 13

Some boards do not enable interupts for the second RS-232 port.  I
tried this out as I was developing a (commercial) communications
package for the IBM PC, and found that the interrupt pin on the second
8250 on a (argh! can't remember the company name.  It was a 256K
memory + 2 serial port board) wasn't connected to ANYTHING!

The reasoning behind this (I assume) is that if you have multiple
chips generating a single interrupt, then you can't trivially figure
out which port the interrupt was actually for.  In particular,
interrupt driven software that assumes only one active port is likely
to break.

Bill Westfield