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Article #5466Re: Looking for 21h and 64h port bit format.
From: Bob Eager
Date: Tue, 26 Mar 1991 16:29
Date: Tue, 26 Mar 1991 16:29
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1543 bytes
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.
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Bob Eager | University of Kent at Canterbury
| +44 227 764000 ext 7589
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Path: arc1-ca.pugleaf.net!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