the logical xor operator!

[Steven Ryan]

The lack of a boolean exclusive-or is probably cultural. Xor is important
for bit fiddling, but few predicates use it. An equivalence operator (even
if it is just a negated xor), on the other hand is useful for boolean but
not bits.

>A good `rule of thumb' is this:
>
>    -------------------------------------------------------------
>    Logical operators are never slower than arithmetic operators.
>    -------------------------------------------------------------
>
>[are there any machines for which this is false?]

Depends how you implement booleans. On a pipelined machine, jumps kill you.