[rescue] sparc10 cpu - what to do.

Dave McGuire mcguire at neurotica.com
Fri Dec 16 14:58:00 CST 2016

On 12/16/2016 02:14 PM, Liam Proven wrote:
>>   The 80486 is little more than an 80386 with an 80387 on-chip.  There
>> are other differences, but that's the main one.
> No, hang on, that is not accurate or fair.

  Oh, here we go.  Liam, I thought you had left that attitude on the
classiccmp list where it belongs.

  Did you conveniently miss the part, still quoted above, when I said
"there are other differences"?

> The 386 is a simple, scalar 32-bit CPU.
> The 486 is pipelined -- it delivered roughly twice the
> instructions-per-clock of the 80386 -- as well as having on-board L1
> cache.
> It was a lot more than a 386+387 on the same die, although the ISA was
> near identical.

  There were something like two additional instructions, yes.  And
you're correct about the pipelining and and cache.  But I'd like to see
a 386 and a 486 side-by-side with the 486 doing twice as many
instructions per MHz than a 386.  I've done those comparisons, albeit
for real (not benchmark-tuned) workloads, and that just doesn't wash.
The main performance benefit of the 486 was due to higher clock speeds,
which are due to process improvements over the intervening years.

> The Pentium Pro has instruction decomposition and reordering.

  The PPro was the first of that family that I consider to be even
halfway reasonable.


Dave McGuire, AK4HZ
New Kensington, PA

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