Article View: comp.sys.ibm.pc
Article #25957Re: PC IO Port bus ?
From: Michael J. Farren
Date: Sun, 27 Mar 1988 15:25
Date: Sun, 27 Mar 1988 15:25
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1295 bytes
In article <166@ucrmath.UUCP> jantypas@hope.UUCP (John Antypas) writes:
>(a) The IBM PC data bus (ie when I do an INP, or OUT port instruction)
> has address decoding already done? What about latching?
No. And, no.
>(b) On the PC, I assume the bus is 16 bits wide (data) with a 16 bit
> address bus? (My AT manual says it is.)
The AT data bus is 16 bits wide, but the original PC data bus is only
8 bits wide. There is an additional connector on the AT bus, carrying
the extra data bits. The original PC's address bus is 20 bits wide,
I believe the AT's is 24, but am not sure.
--
Michael J. Farren | "INVESTIGATE your point of view, don't just
{ucbvax, uunet, hoptoad}! | dogmatize it! Reflect on it and re-evaluate
unisoft!gethen!farren | it. You may want to change your mind someday."
gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!lll-winken!lll-lcc!unisoft!gethen!farren From: farren@gethen.UUCP (Michael J. Farren) Newsgroups: comp.sys.ibm.pc Subject: Re: PC IO Port bus ? Message-ID: <831@gethen.UUCP> Date: 27 Mar 88 15:25:28 GMT References: <166@ucrmath.UUCP> Reply-To: farren@gethen.UUCP (Michael J. Farren) Organization: There's Unix there in Oakland Lines: 18