Explain about the Arithmetic Shift

An arithmetic shift micro operation shifts the signed binary number to left or right.

The effect of the arithmetic shift left operation is to multiply binary number by 2.

Similarly an arithmetic shift right divides number by 2. Since the sign of number  must  remain  same  arithmetic  shift-right  must  leave  sign  bit unchanged, when it is multiplied or divided by 2. The left most bit in a register hold sign bit, and remaining bits hold number. The sign bit is 0 for positive and 1for the negative. Negative numbers exists in 2's complement form. Following figure represents a typical register of n bits.