Electronics and Communication Engineering - Digital Electronics

11. 

A + A . B =

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

Answer: Option C

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

Answer: Option B

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

Answer: Option B

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

Answer: Option B

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

Answer: Option C

Explanation:

Clock period(t) = = 10-7 sec

Number of FF =

mod counter 28 = 256.