1) Only "Two's Complement" signed arithmetic is asymmetric. One's Complement arithmetic wasn't uncommon on computers of the era and is fully symmetric. And, I

1) Only "Two's Complement" signed arithmetic is asymmetric. One's Complement arithmetic wasn't uncommon on computers of the era and is fully symmetric. And, I believe that a PDP-7 uses one's complement. 2) "unsigned" didn't get implemented until about 5 years after C was initially implemented.