# Electronics and Communication Engineering - Digital Electronics

41.

The number of distinct Boolean expression of 4 variables is

 A. 16 B. 256 C. 1024 D. 65536

Explanation:

22n = 224 = 216 .

42.

The fixed count that should be used so that the output register will represent the input for a 6 bit dual slope A/D converter uses a reference of -6v and a 1 MHz clock. It uses a fixed count of 40 (101000).

 A. 000110 B. 0010 C. 1111 D. 011101

Explanation:

If is made to be unity, the O/P count N2 = ei, N1 = 6 = 000110.

43.

For the K map in the given figure the simplified Boolean expression is

 A. A C + A D + ABC B. A C + A D + ABC C. A C + A D + ACD D. A C + A D + AB C

Explanation:

44.

A memory system of size 16 k bytes is to be designed using memory chips which have 12 address lines and 4 data lines each. The number of such chips required to design the memory system is

 A. 2 B. 4 C. 8 D. 18

Explanation:

.

45.

In a 7 segment display, LEDs b and c lit up. The decimal number displayed is

 A. 9 B. 7 C. 3 D. 1