Computer Knowledge

Digital Logic and Microprocessors

735 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

In which ADC, an integrator circuit is driven positive and negative in alternating cycles to ramp down and then up, rather than being reset to 0 volts at the end of every cycle?

  1. Flash Type ADC

  2. R-2R Ladder DAC

  3. Binary Weighted Input DAC

  4. Dual Slope Integrator ADC

  5. Resolution
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the Dual Slope Converter, an integrator circuit is driven positive and negative in alternative cycles to ramp down and up, rather than being reset to 0 volts at the end of every cycle.

Multiple choice

Which of the following can specify the address of the next instruction to be executed, if it is not the one immediately following the branch, in two ways in 8085 processor?

  1. Register Indirect Branch Addressing Mode

  2. Branch Instruction Type Addressing Mode

  3. Direct Addressing Mode

  4. Instruction

  5. Intersegment Indirect Addressing Mode
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

These instructions can specify the address of the next instruction to be executed, if it is not the one immediately following the branch , in two ways in 8085 processor.

Multiple choice

Consider following code

wait (s) : while not (s > 0) do keep testing s : s - 1 Signal(s) : s = s + 1 if value of s is - 2. And a process P executes first instruction, then which of the following is true?

  1. P will be granted to enter critical state

  2. P will not be able to enter critical state and terminate

  3. P will execute first instruction and terminate

  4. P will keep testing until variable s becomes greater than zero

  5. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Here as we know, semaphore variable has value 1 and 0 so if s gets 1 then P has permitted it to enter into critical region.

Multiple choice

The accumulator is a part of the

  1. input unit

  2. output unit

  3. control unit

  4. ALU
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The accumulator is a register in the Arithmetic Logic Unit (ALU) where intermediate arithmetic and logic results are stored. The ALU performs mathematical and logical operations, and the accumulator is central to this process. Input, output, and control units are separate components of the computer architecture.

Multiple choice

Types of flops are

  1. mega flops and tera flops

  2. giga flops and tera flops

  3. giant flops and tera flops

  4. both (1) and (2)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

FLOPS (Floating Point Operations Per Second) measures computer performance in powers of 1000. Both megaFLOPS (10^6 operations/sec) and gigaFLOPS (10^9 operations/sec) are standard units, making option D correct. TeraFLOPS (10^12) is also valid but the question asks which pair is correct, and A-B are indeed real FLOPS types.

Multiple choice

Parallel Adders are

  1. combinational logic circuits

  2. sequential logic circuits

  3. both (1) and (2)

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Parallel adders use combinational logic - they compute sums instantly based solely on current inputs without any memory elements. All full-adder circuits operate simultaneously on all bit positions, hence 'parallel'. Sequential circuits require memory and clock signals, which parallel adders do not use. They are purely feedforward logic networks.

Multiple choice

Which one of the following holds true when a JK flip-flop is constructed from an SR flip-flop?

  1. S = JQ, R = K + JQ'

  2. J = S, K = R

  3. J = S + R' Q, K = S- (R' + Q' )

  4. S = JQ' , R = KQ
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When constructing a JK flip-flop from an SR flip-flop, we need to prevent the invalid state (S=1, R=1) and enable toggling (J=1, K=1). The correct mapping is S = JQ' and R = KQ. When Q=0, S=J and R=0, so setting J=1 sets Q to 1. When Q=1, S=0 and R=K, so setting K=1 resets Q to 0. When J=K=1 and Q=0, the SR inputs become (1,0) setting Q to 1; when Q=1, they become (0,1) resetting Q to 0 - thus toggling.