Binary Subtraction

Negative numbers are represented in 2 complement form and subtraction is also  per formed  using  2 complement  method in microprocessor. Hence we will  discuss only 2  compliment method  of subtraction in this book.

To find  2 compliment of any binary  number

Use followings  steps

Find 1 complement  of the given  binary  number convert all 0 to 1 and  all 1 to 0 s.

Add 1  to the obtained d1  complement number to get the 2 complement of the original number.

The  obtained  binary number will  be the  negative  of the given  number.

Example :  Find 2 complement  of 010110112.  ( equal to + 91¹⁰)

Solution : 1 complement  of the given number is:    10100100

    Add 1                                                                            1

The 2 complement  form of the number                  101000101

This  will represent  -91₁₀ in microprocessor.