Hey guys,

Correct me if I am wrong but Allegro will work with any x86 based microprocessor, correct?

Allegro has to make use of several OS calls so I'd say "works on x86" is the wrong question. The DOS version was quite low level, but depended on the so-called "IBM compatible" architecture.

4.2.x branches support DOS, correct?

They claim to, but all development has stopped on 4.2, and if something doesn't work, you're SOL.