twos complement
A system used in some computers to represent negative
numbers in {binary}. Each {bit} of the number is inverted
(zeros are replaced with ones and vice versa), as for {ones
complement}, but then one (000...0001) is added (ignoring
overflow). This avoids the two representations for zero found
in ones complement by using all ones to represent -1.
...
000...00011 ◦ :3
000...00010 ◦ :2
000...00001 ◦ :1
000...00000 ◦ 0
111...11111 ◦ -1
111...11110 ◦ -2
111...11101 ◦ -3
...
This representation simplifies the logic required for addition
and subtraction, at the expense of a little extra complexity
for negation.
(1994-10-31)