"Bill Daniels" wrote
I still have an IBM PC XT that works as well as the day it was bought back
in 1985. It just doesn't do anything useful in today's world.

There is a Bendix T-12C ADF installed in my airplane. It has been
there for decades and still works as well as it ever did. It just
doesn't do anything useful in today's world.

Well, maybe. In fact it allows me to legally shoot the approach into
my home field. In reality, I shoot it with the panel LORAN and
yokemount GPS - either of which is far more accurate and reliable -
but for the sake of legalities the ADF must be there. In theory I am
supposed to use it as the primary reference, but nobody can prove I
don't.

And thus my point - your IBM PC-XT does nothing useful because the
regulatory climate is quite relaxed in personal computer use. Not so
when it comes to panel-mount avionics in certified aircraft. I fully
expect that the first-generation glass panel displays will still have
significant value a decade from now (and maybe three decades) because
the FAA acts as a massive brake on innovation.

Michael