[82S100 PLA]
It's bipolar and also programable (fuseable links)
and they do have
a tendancy to develop shorted paths where they were once "opened".
Yes, but why is it such a problem in the C64 (and SX64?) Is it just that
so many of those machines were sold that if only 0.1% of them fail it's
still a lot of dead chips? The 82S100 was used in a lot of other things
(including the PDP11/44 IIRC), and you don't hear about those failing all
the time.
-tony