Semi-OT: Interesting or unusual PC Compatibles?

[Fred Cisin]

On Sat, 30 Jun 2007, Chris M wrote:
>  Fine, but does a V40 present the same *possible*
> incompatibility issues as an 80186. And for that
> matter but OI NOT THE ORIGINAL QUESTION does a V20/V30
> present any of it's own...

a few, but very few.  For example, 8086/8088 has a few bugs.  One of those
is that if you have TWO prefixes (segment override , and REP) to a MOVSB,
. . . if there is an interrupt during execution of that instruction, then
the first? prefix is forgotten.  NEC failed to provide that bug in the
V20/V30.
In addition, there are instructions to invoke the 8080 mode of the
V20/V30.  That behaves differently than those instructions on an
8088/8086.