BEE Digital Logic and Systems 4

Question 1

Which sequential circuit element is used to detect a specific binary sequence in a serial data stream?

Accepted Answer

Sequence detector (finite state machine)

Answer

A finite state machine (sequence detector) is designed to recognize a specific pattern in a serial bit stream by transitioning through defined states.

Question 2

How many flip-flops are required to build a MOD-16 counter?

Accepted Answer

4

Answer

A MOD-16 counter cycles through 16 states (0–15), requiring 4 flip-flops since 2⁴ = 16.

Question 3

Gray code is preferred over standard binary in mechanical encoders because:

Accepted Answer

Only one bit changes between consecutive values

Answer

Gray code changes only one bit between consecutive values, preventing erroneous intermediate readings when multiple bits would change simultaneously in binary.

Question 4

What Boolean expression represents an Exclusive-OR (XOR) gate with inputs A and B?

Accepted Answer

A'B + AB'

Answer

XOR outputs 1 when the inputs differ: A'B (A=0,B=1) + AB' (A=1,B=0), written as A ⊕ B.

Question 5

In a 4-to-1 multiplexer, how many select lines are needed?

Accepted Answer

2

Answer

A 4-to-1 MUX has 4 data inputs requiring 2 select lines since 2² = 4 possible selections.

BEE - Bachelor of Electrical Engineering Practice Test

BEE - Bachelor of Electrical Engineering Practice Test

BEE Digital Logic and Systems 4