Development, round II

From: Mike Allison <>
Date: Sun Feb 1 19:33:50 1998

Sorry All:

I've been out of town since early Friday, so I wanted to do some

No, I don't remember that Intel ever had a big prob with the '286. The
first big foul up they had was the something to do with a fraction error
which gave incorrect results on large real fraction. It wasn't an error
problem so much as an accuracy problem. It wasn't good to as many
places as it should have been. There was another '386 bug, as I recall
that broke on certain multiplications or divides, can't remember, they
may have even been the same error.

IBM would have had no reason to "cripple" something with an AT chip in
it. I recall, as Allison states, that it was a way to use up XT
hardware, but put some AT capabilities in. If there were any
limitations it was from the supporting IC's or hardware, NOT the


Allison J Parent wrote:
> <1. The AT had been deliberately set up so that it couldn't make one of
> <the transitions between modes - IBM were being paranoid and thinking of
> <crackers having a back door - but this "feature" was removed in the
> <PS/2.
> Incorrect. the I286 has real and protected modes and intel for some
> wacky reason gave you a way to go from real to protected but not back.
> The only way to get to real mode agan was...reset!
> <2. Intel had a fault on a large batch of 286s that couldn't do some of
> <the things you'd expect. IBM bought a job lot on the cheap and stuck
> <them in XT286s.
> Nope, xt286 was a way to put a cheap system of slightly higher performance
> out there using slower parts.
> Allison
Received on Sun Feb 01 1998 - 19:33:50 GMT

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