# Electronics and Communication Engineering - Digital Electronics

31.

The dual of A + [B + (AC)] + D is

 A. A + [(B (A + C))] + D B. A [B + AC] D C. A + [B (A + C)] D D. A [B (A + C)] D

Explanation:

In taking dual OR is replaced by AND and vice versa.

32.

A divide by 78 counter can be obtained by

 A. 6 numbers of mod-13 counters B. 13 numbers of mod-6 counters C. one mod-13 counter followed by mod-6 counter D. 13 number of mod-13 counters

Explanation:

Modulus 13 x modulus 6 = modulus 78.

33.

The initial state of MOD-16 down counter is 0110. What state will it be after 37 clock pulses?

 A. Indeterminate B. 0110 C. 0101 D. 0001

Explanation:

A mod-16 counter goes through 16 states in one cycle of 16 Pulses.

It complete 2 cycles in 32 Pulses.

In the rest 5 Pulses, it moves down from 0110 = 610 - 510 = 110 or (001)2 .

34.

The number of address lines in EPROM 4096 x 8 is

 A. 2 B. 4 C. 8 D. 12

Explanation:

212 = 4096.

35.

If the inputs to a 3 bit binary adder are 1112 and 1112, the output will be 1102

 A. True B. False