I want to thank the several people who had suggestions concerning
my attempts to run mpsim, mpasm, and mps16C on OLD XT's.  Thanks to some
questions raised by Andy Warren, I dug a little more deeply in to what was
happening.  If anybody else has an old XT lying around, here is what I
discovered.

        It appears that it is simply out of the question to run mpsim on
anything that doesn't have high memory and can't do protected mode.  When I
rant mpsim on a modern 486 machine with Qemm386, I got text output to the
video buffer which is great.  I was afraid that it would try to draw letters
in graphics mode which would pretty well keep it from working with the speech
synthesizer.

        mpasm seemed to run just fine on 2 of the 3 XT's I tried it on which
is also a lucky break.  I haven't connected the programmer and actually tried
to program a PIC yet, but mps16C does produce a proper-looking screen on
IBM XT's with a monochrome display.  It didn't do so well on a couple of
Clones with Hercules-type video displays.  I bet it's a memory conflict
of some kind.

        One person mentioned an ICE or in-circuit emulator.  I know that
such things exist, but am curious as to how they work.  Is there a way to
at least see the contents of the registers of a non-protected PIC as it
is stepped through its program?  I know that time-critical operations would
not necessarily work right, but one could at least test parts of a program
to make sure that it was at least logically correct.

Martin McCormick WB5AGZ  Stillwater, OK 36.7N97.4W
OSU Center for Computing and Information Services Data Communications Group