Evaluate 2’s complement of 8 bits including sign bit. i) Add – 128 and 120 – IGNOU MCA Assignment 2015 – 16

By | September 1, 2015


Course Code : MCS-012
Course Title : Computer Organisation and Assembly Language Programming
Assignment Number : MCA(I)/012/Assignment/15-16
Maximum Marks : 100
Weightage : 25%


Perform the following arithmetic operations using binary signed 2’s complement notation for integers.

You may assume that the maximum size of integers is of 8 bits including the sign bit. (Please note that the numbers given here are in decimal notation)

i) Add – 128 and 120

ii) Subtract 124 from –99

iii) Add 64 and 61

Please indicate the overflow if it is occurs. Also write how you have identified the overflow.

i) Add –128 and 120

First, we have to represent the number in binary notation

The sign of a binary number is represented by 0 as plus and 1 as minus

Sign bit                                 7 -bits

0 / 1

Now, Binary value of the given number

128 – 10000000

120 – 01111000

This number value is of more than 8-bits (i.e.8-bits) in signed 2’s complement notation also the value remains the same. Hence this number cannot fit inside it.

To add this numbers we will need one more bit, hence Addition not possible.