*updating* 8088's - test-drb@ccmp.vtda.org

21 Nov 2007

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Subject: Re: *updating* 8088's
   From: Jim Leonard <trixter at oldskool.org>
   Date: Tue, 20 Nov 2007 19:35:14 -0600
     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>

Chris M wrote:
> --- Alexis <thrashbarg at kaput.homeunix.org> wrote:
>  
>> You might run into an issue of minimum clock speed
>> too. I don't know what
>> the minimum for the 386/486 is. I know RISC
>> microcontrollers can go down to
>> DC, but the 8386/486 might not. 
Correct they are dynamic internally.  The minimum clock is 
far slower than most would tolerate (under 1mhz).


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    Presumably
the boards these things come with have
 their own crystals. I would not expect a '486 upgrade
 for a '286 to run at 8mhz or anything comparable (but
 Tony could tell us). 
They did indeed.  Which brings us to why these were stopgaps at best: 
The processing may have been faster, but the memory/bus interface was 
the same, so you were not truly getting the overall performance of the 
real machine (that's why the advertised benchmarks were careful to 
demonstrate how much faster the upgraded machine was compared to how it 
was before, and NOT to a "real" 386). 
Some resorted to PLL chips top multiply the existing clock to
something fast.

Allison

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 -- 
Jim Leonard (trixter at oldskool.org)            http://www.oldskool.org/
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