In article <199512031711.LAA08465@darkwatch.flame.org>
explorer@flame.org (Michael Graff) writes:

   And another data point on my list is that I have had memory problems
   which were not caught by parity checking.  I had almost six months
   where my computer was unreliable, and the problem was a bad SIMM.
   Once I replaced that everything worked again.  Parity just didn't
   catch that.

Yah, and there was a story a few years ago about a skydiver whose main
parachute and backup parachute both failed to open, who hit the ground
from a N000-foot fall and survived.  That's not the point.

Parity detects a large percentage of errors that would otherwise go
unnoticed.  This is definitely a win.  Perhaps the average Windows
user playing Solitaire or Minesweeper doesn't care, but your average
person *is* going to care if their Quicken or 1-2-3 lies to them, and
they go write a check that bounces or something.

Sure; failures don't happen very often.  But if we built everything
for the common case, failures would always cause your car to explode
and your house to fall down.  This is simply not good engineering
principle.