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From: mikes@iuvax.cs.indiana.edu (Michael Squires)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Comparing 486 to 386 Systems
Summary: 486 gotcha's
Keywords: 486 XCMOS setup cache
Message-ID: <1991Apr7.173227.24870@news.cs.indiana.edu>
Date: 7 Apr 91 22:32:14 GMT
References: <1991Apr4.062503.1325@agate.berkeley.edu> <1991Apr4.142742.20601@lonex.radc.af.mil> <1991Apr6.021141.5859@cc.helsinki.fi>
Organization: Computer Science, Indiana University, Bloomington.
Lines: 16

In article <1991Apr6.021141.5859@cc.helsinki.fi> osmoviita@cc.helsinki.fi writes:
>But I compared 33 Mhz 486 with 8k cache and 25 MHz 386 with 64k cache. The
>25 MHz 386 was faster in some tests until I added additional cache to 486.
>Then the performance of 486 was 4-5 times the performance without cache.
>That was only in tests using lots of memory (e.g. 12 MB).

My 486/25 has only the internal 8K cache.  With the AMI BIOS/OPTI chipset
it turns out that the range of memory which could be cached was set by the
XCMOS settings even when the 8K cache was turned on using jumpers.  I could
not understand why a 486/25 was slower than a 386/20 running UNIX; it turned
out that the 8K cache was only working in the first 1MB.
-- 

Mike Squires (mikes@iuvax.cs.indiana.edu)     812 855 3974 (w) 812 333 6564 (h)
mikes@iuvax.cs.indiana.edu          546 N Park Ridge Rd., Bloomington, IN 47408
Under construction: mikes@sir-alan.cica.indiana.edu