Path: utzoo!utgpu!cunews!bnrgate!bwdls58!mlord
From: mlord@bwdls58.bnr.ca (Mark Lord)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Difference between a 386 and a 386sx
Keywords: 386 386sx
Message-ID: <4405@bwdls58.UUCP>
Date: 22 Sep 90 19:06:12 GMT
References: <1990Sep16.194605.11968@ecn.purdue.edu> <4383@bwdls58.UUCP> <14110@mentor.cc.purdue.edu> <4387@bwdls58.UUCP> <4093@altos86.Altos.COM>
Sender: mlord@bwdls58.UUCP
Reply-To: mlord@bwdls58.bnr.ca (Mark Lord)
Organization: Bell-Northern Research, Ottawa, Canada
Lines: 31

In article <4093@altos86.Altos.COM> rcollins@altos86.UUCP (Robert Collins) writes:
>In article <4387@bwdls58.UUCP> mlord@bwdls58.bnr.ca (Mark Lord) writes:
>>
>>Good in theory.. but cannot be done.  In order to "time" them, 
>>you need to know the exact CPU clock rate, which is another unknown.
>
>It's easy to determine CPU speed.  I've had an algorithm to do this for
>over a year.  It works on 8086, 186, 286, 386SX, 386DX, 486 at any speed
>up to (over) 50Mhz.  Though, I haven't tried it on a 50Mhz CPU (we won't
>get any until next quarter), I have tried it on 386's and 486's up to
>33Mhz in each case.  The algorithm is accurate to 2 decimal places.
>
>The algorithm is independent of, and isn't affected by cache or memory
>speed.

Impressive.  I have yet to see a program which correctly informs me of 
the 18Mhz speed of my 386sx.  Congratulations!

But I'm still doubtful of the applicability of this to determining the
exact CPU type, as in that case the bus-width, caches, wait states etc..
all interfere with any timing-based method of cpu identification.

Remember, even a 386dx could be talking to physical 16-bit memory.
Not common, I admit, but quite possible.  I will not be posting any
code to solve this problem, because I don't WANT any software to be
able to tell the difference.  I LIKE being able to run ALL 386 programs.
-- 
 ___Mark S. Lord__________________________________________
| ..uunet!bnrgate!mlord%bmerh724 | Climb Free Or Die (NH) |
| MLORD@BNR.CA   Ottawa, Ontario | Personal views only.   |
|________________________________|________________________|