Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!apple!baum
From: baum@Apple.COM (Allen J. Baum)
Newsgroups: comp.arch
Subject: Re: Instruction (dis)continuation (
Message-ID: <34732@apple.Apple.COM>
Date: 14 Sep 89 20:47:14 GMT
References: <2353@oakhill.UUCP> <261500010@S34.Prime.COM>
Reply-To: baum@apple.UUCP (Allen Baum)
Organization: Apple Computer, Inc.
Lines: 17

[]
>In article <261500010@S34.Prime.COM> BEAR@S34.Prime.COM writes:
>
>It would appear that what this thread is *really* discussing is whether or
>not MEMORY MAPPED I/O is a good thing. The concensus seems to be that it
>should be avoided (use I/O instructions instead). If it can't be avoided,
>be careful.

OK, I'll bite. What are the characteristics of memory mapped I/O that enable
it to avoid the problems we are talking about? Note that I am assuming that
memory mapped I/O is done with simple Load/Store instructions otherwise, and
not hairy mem-mem translate&test&stand-on-your-head instructions.


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