Re: Difference between a 386 and a 386sx

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#3421

From: Robert Collins
Date: Mon, 24 Sep 1990 20:08

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In article <47642@bigtex.cactus.org> james@bigtex.cactus.org (James Van Artsdalen) writes:
>> Ahha you say, so why not use 32-bit instructions that do not access
>> memory?  Simple reason: that would not tell you anything, since the
>> 386sx IS a 32-bit processor inside the chip.
>
>OK, then let's use 32 bit instructions that *do* access memory.  On an
>SX they'll take long because it takes two cycles.  

Yes, and they will take "long" on a DX with a 16-bit bus...as many 
early '386's had.  

>So one could do a
>"rep stosw" then a "rep stosd" and measure the ratio of time between
>the two...

Oh really?  What if the memory was all across the I/O bus?  Shoot, it
seems that the speed of the I/O bus would shadow the results of this
test.  


-- 
"Worship the Lord your God, and serve him only."  Mat. 4:10
Robert Collins                 UUCP:  ...!sun!altos86!rcollins
HOME:  (408) 225-8002
WORK:  (408) 432-6200 x4356

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!apple!altos!altos86!rcollins
From: rcollins@altos86.Altos.COM (Robert Collins)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Difference between a 386 and a 386sx
Keywords: 386 386sx
Message-ID: <4104@altos86.Altos.COM>
Date: 24 Sep 90 20:08:22 GMT
References: <1990Sep16.194605.11968@ecn.purdue.edu> <4383@bwdls58.UUCP> <14110@mentor.cc.purdue.edu> <4387@bwdls58.UUCP> <47642@bigtex.cactus.org>
Reply-To: rcollins@altos86.UUCP (Robert Collins)
Organization: Altos Computer Systems, San Jose, CA
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