Why the range of 8-bit binary numbers is -128~127

1. There are three ways to represent a signed number in a computer: original code, inverse code, and complement
8-bit source code and inverse code can be expressed in the range of -127~127
8-bit complement can represent the range of numbers is -128~127
So since the range is -128~127, it must be expressed in the complement.

10000000-11111111 means 128 to-1, 00000000-01111111 means 0-127

The complement of 1111 1111 is converted into the original code is 1000 0001, that is-1.

In the complement (-128) instead of (-0), so the complement of the expression range is:

Note: (-128) there is no corresponding source code and anti-code, (-128) = (10000000), 10000000 is reversed plus 1 is-128.

2. The data in the computer is usually stored in the complement, because the CPU can only do the addition operation.

Why the range of 8-bit binary numbers is -128~127