[rescue] A bit of Fun

Geoffrey S. Mendelson gsm at mendelson.com
Tue Jun 17 14:58:03 CDT 2003

Joshua D. Boyd wrote:
> The 80268 and 80386 both peeved me.  Both were good chances to fix
> things, but they didn't.  But the 80286 was worse because you could
> enter protected mode, but you couldn't leave it.  Thus, I never heard of
> a single program that used 80286 protected mode, except OS2.

Windows/286, Coherent, Xenix. Whatever the 286 version of EMM386 was called.

A smart programer got around the problem. They set a bit to zero in memory
and did a cpu reset. A real cpu reset would have left the bit unitialized,
i.e. a one.

Real UNIX was not ported to Intel until the 386. The 386 had 2 features
that were missing in the older processors, a flat address space
(segment addressing was no longer required) and virtual memeory,
it also was able to gracefuly leave protected mode,


Geoffrey S. Mendelson gsm at mendelson.com 972-54-608-069
Do sysadmins count networked sheep?

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