There are three basic ways to represent negative numbers

2's complement

signed magnitude

excess (or bias) notation

2's complement

To represent -5 in binary, take the 2's complement of 5

5 = 00000101

-5 = 11111011

Signed magnitude

To represent -5 in binary, make the first bit a sign bit

5 = 00000101

-5 = 10000101

Excess (or bias) notation

Add the value to the bias. The bias can be any number. Suppose it is 7FH.

5 = 7FH + 5 = 84H = 10000100

-5 = 7FH - 5 = 7AH = 01111010