Electronics and Communication Engineering - Digital Electronics

11.

A + A . B =

 A. B B. A . B C. A D. A or B

Explanation:

A.B= 1 or 0, A + A.B = 0 if A is zero and A + A.B = 1 if A = 1. Hence A + A.B = A.

12.

The device 'one shot' has

 A. two stable states B. one stable state C. either 1 or 2 stable states D. no stable state

Explanation:

One shot means one stable state.

13.

For the logic circuit of the given figure the simplified Boolean expression is

 A. A + BC B. A + BC C. A + B C D. A + BC

Explanation:

= A + BC.

14.

If number of information bits is 4, the parity bits in Hamming code are located at bit positions __________ from the LSB.

 A. 1, 2, 5 B. 1, 2, 4 C. 1, 2, 3 D. 1, 2

Explanation:

The number of parity bits is 3. These bits are located at 20, 21, 22, i.e., 1, 2, 4th bits starting from LSB.

15.

A certain JK FF has tpd = 12 n sec the largest MOD counter that can be constructed from these FF and still operate up to 10 MHz is

 A. any B. 8 C. 256 D. 10

Explanation:

Clock period(t) = = 10-7 sec

Number of FF =

mod counter 28 = 256.