1. Sign and Magnitude Representation
In this system, he most significant (leftmost) bit in the word as a sign bit. If the sign bit
is 0, the number is positive; if the sign bit is 1, the number is negative.
The simplest form of representing sign bit is the sign magnitude representation.
One of the draw back for sign magnitude number is addition and subtraction need to
consider both sign of the numbers and their relative magnitude.
Another drawback is there are two representation for 0(Zero) i.e +0 and -0.
2. One’s Complement (1’s) Representation
In this representation negative values are obtained by complementing each bit of the
corresponding positive number.
For example 1s complement of 0101 is 1010 . The process of forming the 1s
complement of a given number is equivalent to subtracting that number from 2n -1 i.e
from 1111 for 4 bit number.
Two‟s Complement (2‟s) Representation Forming the 2s complement of a number is
done by subtracting that number from 2n . So 2s complement of a number is obtained
by adding 1 to 1s complement of that number.
Ex: 2‟s complement of 0101 is 1010 +1 = 1011
NB: In all systems, the leftmost bit is 0 for positive number and 1 for negative number.
