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MCQOPTIONS
This section includes 2291 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 701. |
Multiplexing of digital signals is usually required when: |
| A. | moving data internally within a microprocessor. |
| B. | moving data between memory and storage registers in a microprocessor. |
| C. | moving data over long distance transmission lines. |
| D. | moving data internally within a microprocessor or between memory and storage registers. |
| Answer» D. moving data internally within a microprocessor or between memory and storage registers. | |
| 702. |
A 16-input multiplexer is to be used to perform parallel-to-serial data conversion. Which of the following counters would be required to provide the data select inputs? |
| A. | MOD 8 |
| B. | MOD 16 |
| C. | MOD 4 |
| D. | MOD 2 |
| Answer» C. MOD 4 | |
| 703. |
A breadboard-circuit design using a BCD-to-decimal decoder has a problem wherein the operation of the system is erratic. The technician uses his scope to examine the waveforms throughout the system and doesn't really see any problems. While he's scratching his head, what helpful advice can you offer him as to what might be wrong and what to do to correct the problem? |
| A. | The decoder is thermally intermittent; replace it. |
| B. | There is probably a bad connection on the wire wrap protoboard; recheck the wiring. |
| C. | Glitches are probably the culprit; strobe the decoder. |
| D. | The decoder is thermally intermittent and must be replaced; or there is probably a bad connection on the wire wrap protoboard, and the wiring must be rechecked. |
| Answer» D. The decoder is thermally intermittent and must be replaced; or there is probably a bad connection on the wire wrap protoboard, and the wiring must be rechecked. | |
| 704. |
Output 5 of a 74138 octal decoder is selected when it is enabled by a data input of: |
| A. | <img src="/_files/images/digital-electronics/digital-systems/mca9_0240a.gif"> |
| B. | <img src="/_files/images/digital-electronics/digital-systems/mca9_0240b.gif"> |
| C. | <img src="/_files/images/digital-electronics/digital-systems/mca9_0240c.gif"> |
| D. | <img src="/_files/images/digital-electronics/digital-systems/mca9_0240d.gif"> |
| Answer» C. <img src="/_files/images/digital-electronics/digital-systems/mca9_0240c.gif"> | |
| 705. |
How is the number one (1) indicated on the outputs of a 7447 BCD-to-seven-segment code converter? |
| A. | Segment a is active. |
| B. | Segment b is active. |
| C. | Segments a and b are active. |
| D. | Segments b and c are active. |
| Answer» E. | |
| 706. |
Decoupling capacitors should be tied from VCC on one device to ground on a different device. |
| A. | True |
| B. | False |
| Answer» C. | |
| 707. |
One example for the use of a Schmitt trigger is as a(n): |
| A. | switch debouncer |
| B. | racer |
| C. | astable oscillator |
| D. | transition pulse generator |
| Answer» B. racer | |
| 708. |
What is the difference between setup time and hold time? |
| A. | Setup time occurs after the active clock edge, hold time occurs before the active clock edge. |
| B. | Setup time occurs before the active clock edge, hold time occurs after the active clock edge. |
| C. | Setup time and hold time both occur at the active clock edge. |
| Answer» C. Setup time and hold time both occur at the active clock edge. | |
| 709. |
Define a race condition for a flip-flop. |
| A. | The inputs to a trigger device are changing slightly before the active trigger edge. |
| B. | The inputs to a trigger device are changing slightly after the active trigger edge. |
| C. | The inputs to a trigger device are changing at the same time as the active trigger edge. |
| Answer» D. | |
| 710. |
How much setup time (ts) is required for the 74LS76? |
| A. | 5 ns |
| B. | 10 ns |
| C. | 20 ns |
| D. | 40 ns |
| Answer» D. 40 ns | |
| 711. |
Why should a LED be pulled LOW from a logic gate rather than pulled HIGH? |
| A. | LOW-level current is smaller. |
| B. | LOW-level current is larger. |
| C. | HIGH-level current is larger. |
| D. | LOW-level current is smaller and HIGH-level current is larger. |
| Answer» C. HIGH-level current is larger. | |
| 712. |
A settable flip-flop's normal starting state when power is first applied to a circuit is always the ________ state. |
| A. | reset |
| B. | set |
| C. | toggle |
| D. | dual |
| Answer» C. toggle | |
| 713. |
In the automatic reset circuit for a flip-flop, how long does it take the capacitor to completely charge? |
| A. | 1 time constant (RC) |
| B. | 2 time constants (RC) |
| C. | 5 time constants (RC) |
| D. | 10 time constants (RC) |
| Answer» D. 10 time constants (RC) | |
| 714. |
The output of a standard TTL NAND gate is used to pull an LED indicator LOW. The LED is in series with a 470- resistor. What is the current in the circuit when the LED is on? |
| A. | 7.02 mA |
| B. | 8.51 mA |
| C. | 10.63 mA |
| D. | 5.32 mA |
| Answer» B. 8.51 mA | |
| 715. |
When the inputs to a flip-flop are changing at the same time that the active trigger edge of the input clock is making its transition, this condition is called: |
| A. | racing |
| B. | toggling |
| C. | slave loading |
| D. | pulse timing |
| Answer» B. toggling | |
| 716. |
Is the propagation delay from the clock to the output for the 7476 the same as the delay from the set or reset to the output? |
| A. | yes |
| B. | no |
| Answer» B. no | |
| 717. |
Describe offset error for a DAC. |
| A. | missing codes |
| B. | error in the slope of the output staircase waveform |
| C. | more or less input voltage is required for the first step than what is specified |
| Answer» D. | |
| 718. |
In an AHDL BCD to binary code converter, how is multiplication by 10 accomplished? |
| A. | By using the shifting of bits |
| B. | By using the library multiplication function |
| C. | By using integer types |
| D. | By using the multiplication operator |
| Answer» B. By using the library multiplication function | |
| 719. |
What is the HDL key issue in the design of the MUX and DEMUX? |
| A. | Having the MUX and DEMUX part of the library |
| B. | Using the case statement in the process |
| C. | Describing the functions |
| D. | Assigning signals under certain conditions |
| Answer» E. | |
| 720. |
Why are control inputs included in an HDL magnitude comparator? |
| A. | For cascading the chips |
| B. | For control signal input |
| C. | For signal control |
| D. | For internal interconnections |
| Answer» B. For control signal input | |
| 721. |
What VHDL techniques are used to describe a priority encoder? |
| A. | Integer outputs and priority coding |
| B. | Signal outputs and priority coding |
| C. | Tristate outputs and priority coding |
| D. | Variables and priority coding |
| Answer» D. Variables and priority coding | |
| 722. |
What is an important attribute of the conditional signal assignment statement? |
| A. | Its tristate outputs |
| B. | Its sequential evaluation |
| C. | Its use of library components |
| D. | Its fast activation times |
| Answer» C. Its use of library components | |
| 723. |
Referring to the figure given below, what output code will appear on the output (A3,A2,A1,A0) when the 5 key is pressed? |
| A. | 1010 |
| B. | 0101 |
| C. | 1101 |
| D. | 1011 |
| Answer» B. 0101 | |
| 724. |
What type of device is shown in the given figure, and what inputs (A3,A2,A1,A0) are required to produce the output levels as shown? |
| A. | A binary-to-decimal encoder; 0,1,1,1 |
| B. | A decimal-to-binary decoder; 1,1,1,0 |
| C. | A BCD-to-decimal decoder; 0,1,1,1 |
| D. | A decimal-to-BCD encoder; 1,1,1,0 |
| Answer» D. A decimal-to-BCD encoder; 1,1,1,0 | |
| 725. |
Which is the decimal number for the BCD number, 10110110? |
| A. | 182 |
| B. | 36 |
| C. | 116 |
| D. | 10110110 is not a valid BCD number. |
| Answer» E. | |
| 726. |
Two principal advantages of the dual-slope ADC are its: |
| A. | high speed and low cost. |
| B. | high sensitivity to noise and low cost. |
| C. | low sensitivity to noise and high speed. |
| D. | low sensitivity to noise and low cost. |
| Answer» E. | |
| 727. |
________ are the most linear of all the temperature transducers. |
| A. | Thermistors |
| B. | Thermocouples |
| C. | IC temperature sensors |
| D. | Resistance temperature detectors |
| Answer» D. Resistance temperature detectors | |
| 728. |
The circuit in Figure 9-8 is defective; data is not appearing on the output lines. A check with the scope shows data pulses on the serial data line and multiplex control lines, S0 S2; no parity error is indicated. A further check with a logic probe indicates that Vcc and ground appear to be present. What might be wrong with the circuit? |
| A. | The demultiplexer may be bad. |
| B. | The parity checker is defective. |
| C. | The parity generator may be bad. |
| D. | The parity checker is defective, or the parity generator may be bad. |
| Answer» B. The parity checker is defective. | |
| 729. |
What is the accuracy of a D/A converter? |
| A. | It is the reciprocal of the number of discrete steps in the D/A output. |
| B. | It is the comparison between the actual output of the converter and its expected output. |
| C. | It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs. |
| D. | It is the deviation between the ideal straight-line output and the actual output of the converter. |
| Answer» C. It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs. | |
| 730. |
An analog quantity varies from 0 7 V and is input to a 6-bit A/D converter. What analog value is represented by each step on the digital output? |
| A. | 0.111 V |
| B. | 1.17 V |
| C. | 0.109 V |
| D. | 0.857 V |
| Answer» B. 1.17 V | |
| 731. |
What is the linearity of a D/A converter? |
| A. | It is the reciprocal of the number of discrete steps in the D/A output. |
| B. | It is the comparison between the actual output of the converter and its expected output. |
| C. | It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs. |
| D. | It is the deviation between the ideal straight-line output and the actual output of the converter. |
| Answer» E. | |
| 732. |
Referring to the given figure, what should the display on the scope look like if the A/D converter is working properly? |
| A. | It should be a circular Lissajous pattern resulting from the simultaneous application of ramps to the vertical and horizontal inputs of the oscilloscope. |
| B. | The pattern should be a straight line across the screen due to the equal but opposite voltages being applied to the scope inputs. |
| C. | A uniform stairstep pattern should be displayed. |
| D. | The scope should display a sequential binary count with the LSB on the left and the MSB on the right side of the display. |
| Answer» D. The scope should display a sequential binary count with the LSB on the left and the MSB on the right side of the display. | |
| 733. |
What type of DAC is shown below? |
| A. | binary-weighted |
| B. | <i>R</i> |
| C. | -2 |
| D. | <i>R</i> |
| E. | ladder |
| Answer» C. -2 | |
| 734. |
What is the disadvantage to using a counter-ramp type ADC? |
| A. | complex circuit |
| B. | high cost |
| C. | very slow |
| Answer» D. | |
| 735. |
Which is not a precaution for handling CMOS? |
| A. | Devices should be placed with pins down on a grounded surface, such as a metal plate. |
| B. | All tools, test equipment, and metal workbenches should be earth grounded. |
| C. | CMOS devices should not be inserted into sockets or PC boards with the power on. |
| D. | Wear wool clothes at all times. |
| Answer» E. | |
| 736. |
Which factor does not affect CMOS loading? |
| A. | Charging time associated with the output resistance of the driving gate |
| B. | Discharging time associated with the output resistance of the driving gate |
| C. | Output capacitance of the load gates |
| D. | Input capacitance of the load gates |
| Answer» D. Input capacitance of the load gates | |
| 737. |
Which is not part of emitter-coupled logic (ECL)? |
| A. | Differential amplifier |
| B. | Bias circuit |
| C. | Emitter-follower circuit |
| D. | Totem-pole circuit |
| Answer» E. | |
| 738. |
Stepper motors have become popular in digital automation systems because ________. |
| A. | of their low cost |
| B. | they are driven by sequential digital signals |
| C. | they can be used to provide repetitive mechanical movement |
| D. | they are driven by sequential digital signals and can be used to provide repetitive mechanical movement |
| Answer» E. | |
| 739. |
The group of bits 11001 is serially shifted (right-most bit first) into a 5-bit parallel output shift register with an initial state 01110. After three clock pulses, the register contains ________. |
| A. | 01110 |
| B. | 00001 |
| C. | 00101 |
| D. | 00110 |
| Answer» D. 00110 | |
| 740. |
A serial in/parallel out, 4-bit shift register initially contains all 1s. The data nibble 0111 is waiting to enter. After four clock pulses, the register contains ________. |
| A. | 0000 |
| B. | 1111 |
| C. | 0111 |
| D. | 1000 |
| Answer» D. 1000 | |
| 741. |
What is meant by parallel load of a shift register? |
| A. | All FFs are preset with data. |
| B. | Each FF is loaded with data, one at a time. |
| Answer» B. Each FF is loaded with data, one at a time. | |
| 742. |
What does the output enable do on the 74395A chip? |
| A. | It determines when data can be loaded. |
| B. | It forces all outputs to go HIGH. |
| C. | It forces all outputs to go LOW. |
| D. | It activates the three-state buffer. |
| Answer» E. | |
| 743. |
To operate correctly, starting a ring shift counter requires: |
| A. | clearing all the flip-flops |
| B. | presetting one flip-flop and clearing all others |
| C. | clearing one flip-flop and presetting all others |
| D. | presetting all the flip-flops |
| Answer» C. clearing one flip-flop and presetting all others | |
| 744. |
In a 6-bit Johnson counter sequence there are a total of how many states, or bit patterns? |
| A. | 2 |
| B. | 6 |
| C. | 12 |
| D. | 24 |
| Answer» D. 24 | |
| 745. |
A modulus-12 ring counter requires a minimum of ________. |
| A. | 10 flip-flops |
| B. | 12 flip-flops |
| C. | 6 flip-flops |
| D. | 2 flip-flops |
| Answer» C. 6 flip-flops | |
| 746. |
How many address bits are needed to select all memory locations in the 2118 16K 1 RAM? |
| A. | 8 |
| B. | 10 |
| C. | 14 |
| D. | 16 |
| Answer» D. 16 | |
| 747. |
The check sum method of testing a ROM: |
| A. | indicates if the data in more than one memory location is incorrect. |
| B. | provides a means for locating and correcting data errors in specific memory locations. |
| C. | allows data errors to be pinpointed to a specific memory location. |
| D. | simply indicates that the contents of the ROM are incorrect. |
| Answer» E. | |
| 748. |
What is the meaning of RAM, and what is its primary role? |
| A. | Readily Available Memory; it is the first level of memory used by the computer in all of its operations. |
| B. | Random Access Memory; it is memory that can be reached by any sub- system within a computer, and at any time. |
| C. | Random Access Memory; it is the memory used for short-term temporary data storage within the computer. |
| D. | Resettable Automatic Memory; it is memory that can be used and then automatically reset, or cleared, after being read from or written to. |
| Answer» D. Resettable Automatic Memory; it is memory that can be used and then automatically reset, or cleared, after being read from or written to. | |
| 749. |
The storage element for a static RAM is the ________. |
| A. | diode |
| B. | resistor |
| C. | capacitor |
| D. | flip-flop |
| Answer» E. | |
| 750. |
In a DRAM, what is the state of R/W during a read operation? |
| A. | Low |
| B. | High |
| C. | Hi-Z |
| D. | None of the above |
| Answer» C. Hi-Z | |