1.NounThe number obtained by subtracting a given n-digit binary number from
2
n
−
1
{\displaystyle 2^{n}-1}
(which yields the same result as the logical complement).
"The ones' complement of 0xAAAA is 0x5555 on a 16-bit machine, and 0xFFFF5555 on a 32-bit machine."
2.NounThe convention by which bit patterns with high bit 0 represent positive numbers from 0 to
2
n
−
1
−
1
{\displaystyle 2^{n-1}-1}
directly, while bit patterns with high bit 1 represent negative numbers from 0 to
−
(
2
n
−
1
−
1
)
{\displaystyle -(2^{n-1}-1)}
, n being the word size of the machine, and the numeric complement of a number is its ones' complement.
"Computers that use ones' complement arithmetic have two representations for zero, all 0's and all 1's."