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- Question
Output 3 of a 74138 octal decoder is selected when it is enabled by a data input of:
A0 = 1
A1 = 1
A2 = 0
Options- A. True
- B. False
- Correct Answer
- True
- 1. If data is brought into the J terminal and its complement to the K terminal, a J-K flip-flop operates as a(n) ________.
Options- A. S-C flip-flop
- B. D flip-flop
- C. gated S-C flip-flop
- D. TOGGLE flip-flop Discuss
- 2. The primary use for Gray code is:
Options- A. coded representation of a shaft's mechanical position
- B. turning on/off software switches
- C. to represent the correct ASCII code to indicate the angular position of a shaft on rotating machinery
- D. to convert the angular position of a shaft on rotating machinery into hexadecimal code Discuss
- 3. All rows in a 2118 dynamic RAM need to be refreshed ________.
Options- A. every second
- B. every millisecond
- C. every 50 milliseconds
- D. every 2 milliseconds Discuss
- 4. A circuit that implements a combinational logic function by storing a list of output values that correspond to all possible input combinations is a(n) ________.
Options- A. output logic macrocell
- B. look-up table
- C. parallel logic expander
- D. logic element Discuss
- 5. Three select lines are required to address four data input lines.
Options- A. True
- B. False Discuss
- 6. If both inputs of an S-R flip-flop are low, what will happen when the clock goes HIGH?
Options- A. An invalid state will exist.
- B. No change will occur in the output.
- C. The output will toggle.
- D. The output will reset. Discuss
- 7. The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:
Options- A. adding a fixed voltage-divider bias resistive network at the output of the TTL device
- B. avoiding this condition and only using TTL to drive TTL
- C. adding an external pull-down resistor to ground
- D. adding an external pull-up resistor to VCC Discuss
- 8. A decoder can be used as a demultiplexer by ________.
Options- A. tying all enable pins LOW
- B. tying all data-select lines LOW
- C. tying all data-select lines HIGH
- D. using the input lines for data selection and an enable line for data input Discuss
- 9. What is the purpose of a decoder's inputs?
Options- A. To allow the decoder to respond to the inputs to activate the correct output gate.
- B. To disable the decoder outputs so that all outputs will be inactive.
- C. To disable the inputs and activate all outputs.
- D. To allow the decoder to respond to the inputs to activate the correct output gate, and to disable the inputs and activate all outputs. Discuss
- 10. A principle regarding most IC decoders is that when the correct input is present, the related output will switch:
Options- A. active-HIGH
- B. to a high impedance
- C. to an open
- D. active-LOW Discuss
More questions
Correct Answer: D flip-flop
Correct Answer: coded representation of a shaft's mechanical position
Correct Answer: every 2 milliseconds
Correct Answer: look-up table
Correct Answer: False
Correct Answer: No change will occur in the output.
Correct Answer: adding an external pull-up resistor to VCC
Correct Answer: using the input lines for data selection and an enable line for data input
Correct Answer: To allow the decoder to respond to the inputs to activate the correct output gate, and to disable the inputs and activate all outputs.
Correct Answer: active-LOW
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