My only experience is anecdotal, not rigorous testing.
I do remember that Norton version 5 took a real hit
when I disabled eternal (L2) cache.  It hit bottom if
I disabled internal cache.  Subjective opinion?  L2 cache
helps on a 486DX33.  However, the point about right-thru
versus write-back cache is on target.  The older right-thru
internal cache is more of a penalty than external cache.
An AMD 486DX2/80 with right-back cache almost paces a DX2/100
with right-thru in benchmarks, and in real life, I prefered my
DX2/80 to my coworkers 100s.  I had some write-thru 80s and they
felt during real usage to be no better than my Cyrix DX2/66.
AMD's are marked -SB for write-back and -VT for write-thru if
I remember right.  As for cpu speed having an impact on cache,
I had to remove several defective COAST (cache on a stick) modules
from AMD586DX/133 computers and performance loss was noticable, so I
don't think high cpu speed makes L2 cache less important.

You probably have a 5 volt board since all 33's were 5 volt.  I can't
remember if Intel had a 5 volt 100, but all the write-back cpus
were 3.45 or 3.3 volt.  These are generally interchangable if your
board supports one or the other.

By the way, you may not like the results you get.  But if
you persist, I did have a 486DX2/66 with 32meg ram and an ISA SCSI card
with an 8 bit SCSI (50 pin connection) Seagate drive (because the
IDE bios was so old it didn't support newer faster ide drives) and the
performance was good enough to use for almost a year. I use a Pentium 120
now
for the same dedicated unattended application.



-----Original Message-----
From: PCBUILD - Personal Computer Hardware discussion List
[mailto:[log in to unmask]]On Behalf Of Herbert Graf
Sent: Monday, April 17, 2000 9:01 PM


> I am working on a old AST Advantage PRO 486DX33 with 16 megs of RAM. I am
> thinking about  upgrading it to a Linux Box for a specific job
> but there is
> one issue. The old Advantage Pro and Bravos were very proprietary and did
> not normally come with an L2 cache....there was a special plug in circuit
> board that was available as an upgrade but now of course this would not be
> available.  The lack of a L2 cache makes for a performance hit but I can't
> remember just how big. I am thinking of upgrading to 32 megs of RAM and a
> DX4100 but something in my memory tells me that without the L2 cache it
> won't be able to benefit from the additional RAM and the Megahertz in an
> efficient manner.
>
> Does anybody remember any hard data as to performance with or without a L2
> cache on a 486 ?

     From what I have experienced L2 cache does not supply as huge a
performance boost as people tend to believe. At higher clock speeds where
the core runs 4 or 5 times the speed of the memory bus L2 certainly becomes
more important (in cases where the L2 runs at either core or close to core
speeds) but in 486 class machines L2 cache has never in my experience
supplied more than about a 5 to 10% boost. L1 cache is much more important.
Now again, it does depend, some tasks benefit from L2 more than others. A
lack of L2 cache will not impede the additional performance of additional
RAM and processing speed. I myself ran a 486DX4/120 (overclocked from 100)
with 16MB and it "managed" win95 OK, not stellar but usable as a backup
system. I have found that Linux is very good at getting every last bit of
performance out of a machine. While X might be a little sluggish on that
machine I am sure that it will run quite well. If you forgo X it will fly
pretty well. Good luck, TTYL

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