Question

Consider that R1 and R2 both are 8
bit registers and contains 01010101 and 10011010 respectively. What will be the values of
select inputs, carry-in input and result of operation (including carry out bit) if the following
micro-operations are performed? (i) Increment R1
(ii) Subtract R2 from R1 with borrow
(iii)Exclusive OR of R1 and R2
(iv)Shift left R1

Answer 1

1.

Increment R1

= 01010101 + 1

Enter Number A

01010101

Enter Number B

00000001

A + B (Binary) = 1010110

A + B (Decimal) = 86

2.

Enter Number A

01010101

Enter Number B

10011010

2's Complement

A - B (Binary) = 1000101

A - B (Decimal) = -69

Input Data :

Binary Input 1 = 01010101

Binary Input 2 = 10011010

Obejective :

010101012 - 100110102 = ?

Find 2's complement of 10011010

1's complement of 10011010 = 01100101

2's complement of 10011010 = 01100101

1

01100110

Input 1 01010101

2's Complement of 10011010 01100110

Sum 10111011

As the sum has no carry take 2's complement for 10111011 and add negative sign

1's complement of 10111011 = 01000100

2's complement of 10111011 = 01000100

1

01000101

01010101 - 10011010 = -01000101

3.

A Ex OR B

Enter Number A

01010101

Enter Number B

10011010

A + B (Binary) = 11101111

A + B (Decimal) = 239

4.

Shift left R1

10101010