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 of the following circuits, the register monitors the comprator's output to see if the binary count is less than or greater than the analog signal input, adjusting the bit values accordingly?

  1. Resolution

  2. Nyquist Frequency

  3. R-2R Ladder DAC

  4. Single-Slope Integrating ADC

  5. Successive Approximation ADC
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Here, the register monitors the comprator's output to see if the binary count is less than or greater than the analog signal input, adjusting the bit values accordingly.

Multiple choice

Which of the following flags is set to a 1 by the instruction just ending if a carry occurred from 4th bit i.e 0, 1, 2 and 3rd bit of the A register during the instruction's execution in 8085 processor?

  1. Carry Flag

  2. Zero Flag

  3. Auxiliary Carry Flag

  4. Sign Flag

  5. Clock
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This flag is set to a 1 by the instruction just ending if a carry occurred from  4th bit i.e 0, 1, 2, 3rd bit of the A register during the instruction's execution in 8085 processor.

Multiple choice

JK master-slave flip-flop resolves the race problem using two flip-flops. These flip-flops are connected in which of the following patterns?

  1. Cascaded to each other and clock is applied to master flip-flop

  2. Cascaded to each other, but the clock is applied to both master and slave simultaneously

  3. Cascaded to each other and the outputs of master flip-flop are cross-coupled to inputs of slave

  4. Crossed-coupled to each other

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In JK flip-flop, the clock is applied to both flip-flops. The master-slave action is controlled by the Q output of master. The answer is correct.

Multiple choice

If the timer 8254 is used in a microprocessor, then the counters always count down. To accomplish this, the counters contain which of the following registers?

  1. Serial-in and serial-out

  2. Parallel-in and parallel-out

  3. Parallel-in and serial-out

  4. Serial-in and parallel-out

  5. Clock in at parallel-out and no clock at clock input
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In 8254, one has to provide the initial value in binary form. This value will provide the required delay. At start, this binary value is loaded to the counter. This is done using parallel-in concept of the shift register. The counter counts down and provides the value to 8254 for comparison with zero. For this, a parallel output stream is used. So, the concept of shift registers is parallel-in and parallel-out.