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

Directions : Two products are sold from a vending machine, which has two push buttons P1 and P2. When a button is pressed, the price of the corresponding product is displayed in a 7 - segment display. If no buttons are pressed, '0' is displayed signifying 'Rs 0'. If only P1 is pressed, '2' is displayed, signifying 'Rs. 2'. If only P2 is pressed, '5' is displayed, signifying 'Rs. 5'. If both P1 and P2 are pressed, 'E' is displayed, signifying 'Error' The names of the segments in the 7 - segment display, and the glow of the display for '0', '2', '5' and 'E' are shown below.

Consider (1) push buttons pressed/not pressed in equivalent to logic 1/0 respectively. (2) a segment glowing/not glowing in the display is equivalent to logic 1/0 respectively.

What are the minimum numbers of NOT gates and 2 - input OR gates required to design the logic of the driver for this 7 - Segment display?

  1. 3 NOT and 4 OR

  2. 2 NOT and 4 OR

  3. 1 NOT and 3 OR

  4. 2 NOT and 3 OR
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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Multiple choice

The output of the 74 series of TTL gates is taken from a BJT in

  1. totem pole and common collector configuration

  2. either totem pole or open collector configuration

  3. common base configuration

  4. common collector configuration
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When output of the 74 series gate of TTL gates is taken from BJT then the configuration is either totem pole or open collector configuration.

Multiple choice

Directions : Two products are sold from a vending machine, which has two push buttons P1 and P2. When a button is pressed, the price of the corresponding product is displayed in a 7 - segment display. If no buttons are pressed, '0' is displayed signifying 'Rs 0'. If only P1 is pressed, '2' is displayed, signifying 'Rs. 2' If only P2 is pressed '5' is displayed, signifying 'Rs. 5' If both P1 and P2 are pressed, 'E' is displayed, signifying 'Error' The names of the segments in the 7 - segment display, and the glow of the display for '0', '2', '5' and 'E' are shown below.

Consider (1) push buttons pressed/not pressed in equivalent to logic 1/0 respectively. (2) a segment glowing/not glowing in the display is equivalent to logic 1/0 respectively.

If segments a to g are considered as functions of P1 and P2, which of the following is correct?
  1. g = $\overline P_1$+ P2, d = c + e

  2. g = P1+ P2, d = c + e
  3. g = $\overline P_1$+ P2, e = b + c

  4. g = P1+ P2, e = b + c
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Multiple choice

Choose the correct one from among the alternatives A, B, C, D, after matching an item from Group 1 most appropriate item in Group 2. Group 1 Group 2 P. Shift register 1. Frequency division Q. Counter 2. Addressing in memory chips R. Decoder 3. Serial to parallel data conversion

  1. P - 3, Q - 2, R - 1

  2. P - 3, Q - 1, R - 2

  3. P - 2, Q - 1, R - 3

  4. P - 1, Q - 2, R - 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Shift Register $\rightarrow$ Serial to parallel data conversion Counter $\rightarrow$ Frequency division Decoder $\rightarrow$ Addressing in memory chips.

Multiple choice

A master - slave flip flop has the characteristic that

  1. change in the output immediately reflects in the output

  2. change in the output occurs when the state of the master is affected

  3. change in the output occurs when the state of the slave is affected

  4. both the master and the slave states are affected at the same time
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A master slave D-flip flop is shown in the figure.  In the circuit we can see that output of flip-flop call be triggered only by transition of clock from 1 to 0 or when state of slave latch is affected.