# Digital Concept MCQs (Digital Logic Design)

Q1. Compared to analog systems, digital systems.

A. are less prone to noise.

B. can represent an infinite number of values.

C. can handle much higher power.

D. all of the above.

Answer= are less prone to noise

Q2. Any number with an exponent of zero is equal to:.

A. Zero.

B. One.

C. That number.

D. Ten.

Q3. In the decimal numbering system, what is the MSD?.

A. The middle digit of a stream of numbers.

B. The digit to the right of the decimal point.

C. The last digit on the right.

D. The digit with the most weight.

Answer= The digit with the most weight

Q4. Parallel format means that:.

A. Each digital signal has its own conductor..

B. Several digital signals are sent on each conductor..

C. Both binary and hexadecimal can be used..

D. No clock is needed..

Answer= Each digital signal has its own conductor.

Q5. A decoder converts ________..

A. Noncoded information into coded form.

B. Coded information into noncoded form.

C. HIGHs to LOWs.

D. LOWs to HIGHs.

Answer= Coded information into noncoded form

Q6. A DAC changes ________..

A. An analog signal into digital data.

B. Digital data into an analog signal.

C. Digital data into an amplified signal.

D. None of the above.

Answer= Digital data into an analog signal

Q7. The output of a NOT gate is HIGH when ________..

A. The input is LOW.

B. The input is HIGH.

C. The input changes from LOW to HIGH.

D. Voltage is removed from the gate.

Q8. The output of an OR gate is LOW when ________..

A. All inputs are LOW.

B. Any input is LOW.

C. Any input is HIGH.

D. All inputs are HIGH.

Q9. Which of the following is not an analog device?.

A. Thermocouple.

B. Current flow in a circuit.

C. Light switch.

D. Audio microphone.

Q10. A demultiplexer has ________..

A. One data input and a number of selection inputs, and they have several outputs.

B. One input and one output.

C. Several inputs and several outputs.

D. Several inputs and one output.

Answer= One data input and a number of selection inputs, and they have several outputs

Q11. A flip-flop has ________..

A. One stable state.

B. No stable states.

C. Two stable states.

D. None of the above.

Q12. Digital signals transmitted on a single conductor (and a ground) must be transmitted in:.

A. Slow speed..

B. Parallel..

C. Analog..

D. Serial..

Q13. In a certain digital waveform, the period is four times the pulse width. The duty cycle is ________..

A. 0%.

B. 25%.

C. 50%.

D. 100%.

Q14. Which of the following statements does NOT describe an advantage of digital technology?.

A. The values may vary over a continuous range..

B. The circuits are less affected by noise..

C. The operation can be programmed..

D. Information storage is easy..

Answer= The values may vary over a continuous range.

Q15. The generic array logic (GAL) device is ________..

A. One-time programmable.

B. Reprogrammable.

C. A CMOS device.

D. Reprogrammable and a CMOS device.

Q16. The range of voltages between VL(max) and VH(min) are ________..

A. Unknown.

B. Unnecessary.

C. Unacceptable.

D. Between 2 V and 5 V.

Q17. What is a digital-to-analog converter?.

A. It takes the digital information from an audio CD and converts it to a usable form..

B. It allows the use of cheaper analog techniQs, which are always simpler..

C. It stores digital data on a hard drive..

D. It converts direct current to alternating current..

Answer= It takes the digital information from an audio CD and converts it to a usable form.

Q18. What are the symbols used to represent digits in the binary number system?.

A. 0,1.

B. 0,1,2.

C. 0 through 8.

D. 1,2.

Q19. A full subtracter circuit requires ________..

A. Two inputs and two outputs.

B. Two inputs and three outputs.

C. Three inputs and one output.

D. Three inputs and two outputs.

Answer= Three inputs and two outputs

Q20. The output of an AND gate is LOW ________..

A. All the time.

B. When any input is LOW.

C. When any input is HIGH.

D. When all inputs are HIGH.

Answer= When any input is LOW

Q21. Give the decimal value of binary 10010..

A. 6(10).

B. 9(10).

C. 18(10).

D. 20(10).

Q22. In positive logic, ________..

A. a HIGH = 1, a LOW = 0.

B. a LOW = 1, a HIGH = 0.

C. Only HIGHs are present.

D. Only LOWs are present.

Answer= a HIGH = 1, a LOW = 0

Q23. Convert the fractional binary number 0000.1010 to decimal..

A. 0.625.

B. 0.5.

C. 0.55.

D. 0.1.

Q24. Digital representations of numerical values of quantities may BEST be described as having characteristics:.

A. That are difficult to interpret because they are continuously changing..

B. That vary constantly over a continuous range of values..

C. That vary in constant and direct proportion to the values they represent..

D. That vary in discrete steps in proportion to the values they represent..

Answer= That vary in discrete steps in proportion to the values they represent.

Q25. A common instrument used in troubleshooting a digital circuit is a(n) ________..

A. Logic probe.

B. Oscilloscope.

C. Pulser.

D. All of the above.

Q26. The parallel transmission of digital data:.

A. Is much slower than the serial transmission of data..

B. Requires only one signal line between sender and receiver..

C. Requires as many signal lines between sender and receiver as there are data bits..

D. Is less expensive than the serial method of data transmission..

Answer= Requires as many signal lines between sender and receiver as there are data bits.

Q27. Convert the fractional decimal number 6.75 to binary..

A. 111.11.

B. 110.101.

C. 110.11.

D. 110.011.

Q28. What is one relative disadvantage of serial transfer?.

A. It requires too many conductors..

B. Its interconnect system is complex..

C. It is slow..

D. It can only be used over very short distances..

Q29. Which format requires fewer conductors?.

A. Parallel.

B. Serial.

C. Both are the same.

D. Cannot tell.

Q30. A pulse has a period of 15 ms. Its freQncy is ________..

A. 6.66 Hz.

B. 66.66 Hz.

C. 666.66 Hz.

D. 15 Hz.

Q31. Give the decimal value of binary 10000110..

A. 134(10).

B. 144(10).

C. 110(10).

D. 126(10).

Q32. The rise time is the time it takes a pulse to go from ________..

A. The base line to the maximum HIGH voltage.

B. 10% of the pulse amplitude to the maximum HIGH voltage.

C. The base line to 90% of the pulse amplitude.

D. 10% of the pulse amplitude to 90% of the pulse amplitude.

Answer= 10% of the pulse amplitude to 90% of the pulse amplitude

Q33. What is an analog-to-digital converter?.

A. It makes digital signals..

B. It takes analog signals and puts them in digital format..

C. It allows the use of digital signals in everyday life..

D. It stores information on a CD..

Answer= It takes analog signals and puts them in digital format.

Q34. A multiplexer has ________..

A. One input and several outputs.

B. One input and one output.

C. Several inputs and several outputs.

D. Several inputs and one output.

Answer= Several inputs and one output

Q35. What is the decimal value of 2^3 ?.

A. 2.

B. 4.

C. 6.

D. 8.

Q36. What kind of logic device or circuit is used to store information?.

A. Counter.

B. Register.

C. Inverter.

D. Buffer.

Q37. PLCC packages have leads on ________..

A. One side.

B. Two sides.

C. Three sides.

D. Four sides.

Q38. What is the typical invalid voltage for a binary signal?.

A. 0.7-2.8 volts.

B. 0.8-3 volts.

C. 0.8-2 volts.

D. 0.7-2.5 volts.

Q39. Convert the fractional binary number 0001.0010 to decimal..

A. 1.4.

B. 1.125.

C. 1.2.

D. 1.8.

Q40. Convert the fractional binary number 10010.0100 to decimal..

A. 24.5.

B. 18.25.

C. 18.4.

D. 16.25.

Q41. How many binary bits are necessary to represent 748 different numbers?.

A. 9.

B. 7.

C. 10.

D. 8.

Q42. A periodic digital waveform has a pulse width (tw) of 6 ms and a period (T) of 18 ms. The duty cycle is ________..

A. 3.30%.

B. 33.30%.

C. 6%.

D. 18%.

Q43. Any number with an exponent of one is equal to:.

A. Zero..

B. One..

C. Two..

D. That number..

Q44. Serial format means digital signals are:.

A. Sent over many conductors simultaneously..

B. Sent over one conductor seQntially..

C. Sent in groups of eight signals..

D. Sent in binary coded decimal..

Answer= Sent over one conductor seQntially.

Q45. What is the decimal value of 2^(-1) ?.

A. 0.5.

B. 0.25.

C. 0.05.

D. 0.1.

Q46. Which format can send several bits of information faster?.

A. Parallel.

B. Serial.

C. Both are the same.

D. Cannot tell.

Q47. The freQncy of a pulse train is 2 kHz. The pulse period is ________..

A. 5 ms.

B. 50 ms.

C. 500 micro-seconds.

D. 2 micro-seconds.

Q48. A type of digital circuit technology that uses bipolar junction transistors is ________..

A. TTL.

B. CMOS.

C. LSI.

D. NMOS.

Q49. How many uniQ symbols are used in the decimal number system?.

A. One.

B. Nine.

C. Ten.

D. Unlimited.

Q50. A classification of ICs with complexities of 12 to 100 equivalent gates on a chip is known as ________..

A. SSI.

B. MSI.

C. LSI.

D. VLSI.

Q51. Which of the following is a semiconductor memory?.

A. RAM.

B. MAR.

C. CD-ROM.

D. CD.