Signed overflow optimization hazards in the kernel

» I suspect that the dominance of twos complement was not due to ease of use, but rather due to the fact that it allows a single hardware adder to perform both signed and unsigned computations. «

My recollection of those days is that the greater motivation was to get away from systems with two different representations of zero. There were ancient Fortran codes run on CDC mainframes that had to test results for both postive and negative zero.