There may be slight differences between the portable and machine
independent versions of the bogomips program. On my system (Linux
1.0.9, 386DX-40, gcc 2.5.8) I get the same results, but they may vary
with other compilers or processors. Compiling without optimization
certainly makes a difference.

When running on a new platform, look at the generated assembly
code. The compiler might try to optimize out the delay() function. If
so, compile with less optimization or try making the loop counter
("i") volatile.
