------------much snipping----------
Semiconductors fatigue. Their parts don't vibrate. They are not as
susceptible to variations in moisture and other environmental factors.
If I were to go dig out an old 1984 IBM PC from my schools computer lab
closet and flip the switch, it might not start, but that would be due
to rust on the mechanics. I could take the board out, put it in a
non-rusty case, power it, and it will boot. And it will compute up to
4.77 million instructions per second thereafter, and continue to do so
for 1000 years provided I did not drop or fry it.

They are certainly more repeatable over a modest period of time. However,
it is my understanding that the molecules in the critical substrates do
migrate over time, and also due to temperature and electrical events. So,
presuming that "normal" operation was not too close to any critical speed,
voltage, or temperature; the 21 years since 1984, or a few more years into
the future, should not be troublesome. However, 1000 years really is taking
"poetic lecense" over the top.