jantypas@hope.UUCP (John Antypas) (03/25/88)
A simplistic question. Would anyone out there know if:
(a) The IBM PC data bus (ie when I do an INP, or OUT port instruction)
has address decoding already done? What about latching?
(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.)
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Internet: jantypas%soft21.UUCP@{eddie.MIT.EDU, UCSD.EDU, uunet.UU.NET}farren@gethen.UUCP (Michael J. Farren) (03/27/88)
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