Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!uunet!mcsun!ukc!harrier.ukc.ac.uk!zodiac.ukc.ac.uk!cur022
From: cur022%cluster@ukc.ac.uk (Bob Eager)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Looking for 21h and 64h port bit format.
Message-ID: <22170.27ef76e9@cluster@ukc.ac.uk>
Date: 26 Mar 91 16:29:28 GMT
Article-I.D.: cluster@.22170.27ef76e9
References: <1991Mar25.055908.2257@msuinfo.cl.msu.edu>
Organization: Computing Lab, University of Kent at Canterbury, UK.
Lines: 16

In article <1991Mar25.055908.2257@msuinfo.cl.msu.edu>, leeda@frith.egr.msu.edu (Dae Hee Lee) writes:
> Could you help me looking for 21h and 64h port bit format for ibm pc?
> Where can I find the documentation on this?

For the 21H port, look in any Intel parts book under interrupt controllers
(8259). The port is a mask (called OCW1) to enable/disable interrupts on the
eight IRQ lines - the bit is set to one to disable interrupts.

I don't recall offhand what 64H does - it is connected to a programmable
peripheral controller, which sends various bits of various ports to different
places. The IBM PC Technical Reference will say. I am not near my copy at
present, but get back to me if no-one else replies.
-------------------------+-------------------------------------------------
Bob Eager                | University of Kent at Canterbury
                         | +44 227 764000 ext 7589
-------------------------+-------------------------------------------------