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Subjectre: AMD (again)

Sorry about the empty message I sent before.

In regards to the AMD 5x85-P75 chip
Jim Nance write:

> What is it missing that makes it non-pentium-class?
> Jim

There are several major differences between the pentium class of chips
and the 486 class of chips. Some of them are:

The 486 has a single instruction pipeline.
The pentium has multiple instruction pipelines.

The 486 has a 32-bit data bus.
The pentuim has a 64-bit data bus.

The 486 has a fixed 4k page size.
The pentuim has 4k and 4M page sizes.

The 486 has a small set of specialized registers.
The pentuim has a much larger set of generalized registers (which are
aliased to mimick the 486 registers for multiple simulteneous
instruction pipes).

The pentium has a superset of the 486 instruction set.

The pentium has specialized hardware for handling bus contentions in
multiprocessor environments.

Because of these enhancements, the pentium outperforms the 486 about
2x1 at the same clock speed. That's why the AMD chip has to run at
133MHz to get performance similar to a pentium class chip running at

IMHO, the AMD gives you much more bang for the buck. One could argue
that it greatly limits one's upgrade options, but I don't think that's
such a strong argument. Motherboard technology is advancing very
quickly, and even if one were to puchase a pentium now, the next upgrade
will probably not be for quite some time (say a year), and by then the
PPro will be the mainstream "affordable" chip. So, most likely you'll
be wanting a new motherboard to go with your new PPro anyhow.

One big caveat that I would throw in is to make sure you get a PCI
motherboard. VLB and pentium/PPro don't mix well and you may want to
keep your cards when you go to step up your motherboard.

Hope that helps,

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