Electronics and Communication Engineering - Digital Electronics

11. 

A 4 bit down counter starts counting from 1111 irrespective of modulus.

A. True
B. False

Answer: Option B

Explanation:

The starting count depends on modulus. 4 bit decade down counter starts counting from 1010.


12. 

The number of counter states which an 8 bit stair step A/D converter has to pass through before conversion takes place is equal to

A. 1
B. 8
C. 255
D. 256

Answer: Option D

Explanation:

28 = 256.


13. 

74 HC series can sink upto 4 mA. The 74 LS series has IIL(max) - 0.4 mA. How many 74 LS inputs be driven by 74 HC output?

A. 100
B. none
C. 8
D. 10

Answer: Option D

Explanation:

.


14. 

An 8 bit transistor register has output voltage of low-high-low-high-low-high-low-high. The decimal number stored is

A. 105
B. 95
C. 85
D. 75

Answer: Option C

Explanation:

01010101 in binary and 64 + 16 + 4 + 1 = 85 in decimal.


15. 

The number of cells in a 4 variable K map is

A. 16
B. 8
C. 4
D. 32

Answer: Option A

Explanation:

24 = 16.