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From: ted@helios.ucsc.edu (Ted Cantrall)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Difference between a 386 and a 386sx
Keywords: 386 386sx
Message-ID: <7132@darkstar.ucsc.edu>
Date: 24 Sep 90 20:27:34 GMT
References: <1990Sep16.194605.11968@ecn.purdue.edu> <4383@bwdls58.UUCP> <14110@mentor.cc.purdue.edu> <4088@altos86.Altos.COM>
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Reply-To: ted@helios.ucsc.edu (Ted Cantrall)
Organization: UCO/Lick Observatory, Santa Cruz
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In article <4088@altos86.Altos.COM> rcollins@altos86.UUCP (Robert Collins) writes:
>In article <14110@mentor.cc.purdue.edu> edgincd2@mentor.cc.purdue.edu (Chris Edgington *Computer Science Major*) writes:
>>If you wanted to determine whether or not the chip you are using is a 386
>>or a 386sx, couldn't you just execute some 32 bit intructions and time the
>>number of machine cycles it takes to execute them.
The internal, CPU-bound instructions would time out the same for the
386SX and for the 386DX (assumption #1).
The external, bus-bound instructions would be faster on teh 386DX than on
the 386SX (assumption #2). (seems safe...;-)
The actual time used by any set of instructions is dependant on an unknown
system clock rate (assumption #3). (seems even safer!)
Possible solution: Run a set of CPU-bound instructions and a set of bus-
bound instructions and compare the times. The ratio sould give a consistant,
reliable difference.
(I just have no idea how to go about timing such things)
				-ted-
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