[PD] Arduino

[Charles Henry]

Okay, I think I get it now.  This may be just the thing I'm looking
for to fix a broken board on a CNC lathe...the lathe is so old that no
one builds replacement boards...but there's intact sensors and
velocity control units.
I still don't understand what the clock rate is like for the digital
in/out pins.  If you were trying to sense an optical encoder for
instance, what would be the maximum rate you could detect?
Chuck