Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!altos!altos86!rcollins
From: rcollins@altos86.Altos.COM (Robert Collins)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: finding out MHz rate of processor (like norton 5.0 )
Keywords: MHz speed processors norton
Message-ID: <4738@altos86.Altos.COM>
Date: 14 Feb 91 16:43:27 GMT
References: <4833@ruuinf.cs.ruu.nl>
Reply-To: rcollins@altos86.UUCP (Robert Collins)
Organization: Altos Computer Systems, San Jose, CA
Lines: 36

In article <4833@ruuinf.cs.ruu.nl> ajbanck@cs.ruu.nl (Arent Banck) writes:
>Looking at the norton utilities 5.0, I saw that it checked the 
>freq. at wich the processor runs.
>Does anybody know if there is an easy way of finding this freq.
>And where I can find this. Also, does anybody know how nu is checking
>this frequency?
>
I would be very suprised if anybody at Norton has actually figured out
a way to check CPU frequency, regardless of the fact that it's not that
difficult.  At least until Norton 4.5, they were executing an instruction
mix and comparing the results to known results of IBM, et al and using 
that as a comparative rating in MHZ.  I haven't seen norton 5.0, but
from my past history of Norton, this has been the way they have done it
all along...so why change it on 5.0?

However, to answer your question, to determing CPU frequency, try executing
a sequence of instructions that perform NO memory or bus cycles, and take
longer to execute than prefetch time.  Time this with the 8254, and do some
simple math and you have the CPU clock frequency.

Of corse my solution sounds simplistic, but it is hardly trivial to
implement.  For example, my own source code is rather short, but the
comments that describe the algorithm in grubby detail are over a page
long.  In other words, you will have to know a lot about how the CPU
operates, how to program the hardware, and do LOTS of thinking on
this one.

Good luck, and no I won't post the algorithm.



-- 
"Worship the Lord your God, and serve him only."  Mat. 4:10
Robert Collins                 UUCP:  ...!sun!altos86!rcollins
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