Computer Knowledge

Digital Logic and Microprocessors

749 Questions

Digital logic and microprocessors form the core of computer science, covering logic gates, combinational and sequential circuits, and CPU architecture. These topics are crucial for computer knowledge sections in technical exams. Test your digital electronics basics here.

Logic gates and circuitsCombinational vs sequential circuitsMicroprocessor instructionsTruth tables and boolean functions

Digital Logic and Microprocessors Questions

Multiple choice

The Boolean expression F(X, Y, Z) = $\bar{X}Y \bar{Z} + X\bar{Y}\bar{Z} + XY\bar{Z} + XYZ$ converted into the canonical product of sum (POS) form is
  1. (X + Y + Z) (X + Y + $\bar{Z}$) (X + Y + $\bar{Z}$) ($\bar{X}$ + Y + $\bar{Z}$)
  2. (X + $\bar{Y}$ + Z) ($\bar{X}$ + Y + $\bar{Z}$) ($\bar{X}$ + $\bar{Y}$ + Z) ($\bar{X}$ + $\bar{Y}$ + $\bar{Z}$)
  3. (X + Y + Z) ($\bar{X}$ + Y + $\bar{Z}$) (X + $\bar{Y}$ + Z) ($\bar{X}$ + $\bar{Y}$ + $\bar{Z}$)
  4. (X + $\bar{Y}$ + $\bar{Z}$) (X + Y + Z) (X + $\bar{Y}$ + Z) (X + Y + Z)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Multiple choice

The digital logic shown in the figure satisfies the given state diagram when Q1 is connected to input A of the XOR gate.

Suppose the XOR gate is replaced by an XNOR gate. Which one of the following options preserves the state diagram?
  1. Input A is connected to $\overline{Q_2}$
  2. Input A is connected to $\overline{Q_2}$
  3. Input A is connected to $\overline{Q_1}$ and S is complemented
  4. Input A is connected to $\overline{Q_1}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\text{When $Q_1$, is connectede to input A, then we have the input $D_2$ as} \\ D_2 = A \oplus S \\ \hspace{0.6cm} = Q-1 \oplus S = Q_1 \bar{S} + \bar{Q_1}S$

Multiple choice

The circuit shown below consists of JK flip-flops, each with an active low asynchronous reset ($\bar{R}_d$ input). The counter corresponding to this circuit is

  1. a modulo-5 binary up counter

  2. a modulo-6 binary down counter

  3. a modulo-5 binary down counter

  4. a modulo-6 binary up counter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

From the figure, it can be seen that it is a basic modulo UP counter configuration because clock is negative edge triggering at modulo-5.

Multiple choice

A universal logic gate can implement any Boolean function by connecting sufficient number of them appropriately. The three are as follows:

Which of the following statements is TRUE?

  1. Gate 1 is a universal gate.

  2. Gate 2 is a universal gate.

  3. Gate 3 is a universal gate.

  4. None of the gates shown is a universal gate.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In general, the only universal gates are NAND and NOR gates, but none of the given gates is NAND or NOR gate. However, we must observe gate 3. All the Boolean functions can be implemented by using this gate. Hence, it is a universal gate.