B CompE Bachelor of Computer Engineering Digital Logic Design

Question 1

What is the output of an AND gate when both inputs are 1?

Accepted Answer

1

Answer

An AND gate outputs 1 (HIGH) only when all of its inputs are 1; with both inputs at 1, the output is 1.

Question 2

Which Boolean expression represents De Morgan's first theorem?

Accepted Answer

(A·B)' = A'+B'

Answer

De Morgan's first theorem states that the complement of a product (NAND) equals the sum of the complements: (A·B)' = A' + B'.

Question 3

How many bits are in one hexadecimal digit?

Accepted Answer

4

Answer

One hexadecimal digit represents exactly 4 bits, since hex uses base 16 and 2^4 = 16 possible values (0–F).

Question 4

What is the 2's complement representation of -5 in an 8-bit system?

Accepted Answer

11111011

Answer

To find 2's complement of -5: 5 = 00000101, invert to get 11111010, then add 1 to get 11111011.

Question 5

Which logic gate produces an output of 1 only when the number of 1 inputs is odd?

Accepted Answer

XOR gate

Answer

An XOR (exclusive OR) gate outputs 1 when an odd number of its inputs are 1, making it useful in parity checking and addition circuits.

B CompE Bachelor of Computer Engineering Practice Test