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Home ‣ Digital Electronics ‣ Combinational Logic Circuits See What Others Are Saying!
- Question
How many outputs would two 8-line-to-3-line encoders, expanded to a 16-line-to-4-line encoder, have?
Options- A. 3
- B. 4
- C. 5
- D. 6
- Correct Answer
- 4
- 1. What type of logic circuit is represented by the figure shown below?
Options- A. XOR
- B. XNOR
- C. XAND
- D. XNAND Discuss
- 2. The principal advantage of MOS ICs over TTL ICs is their fast operating speed.
Options- A. True
- B. False Discuss
- 3. What is the difference between a 7400 and a 7411 IC?
Options- A. 7400 has two four-input NAND gates; 7411 has three three-input AND gates
- B. 7400 has four two-input NAND gates; 7411 has three three-input AND gates
- C. 7400 has two four-input AND gates; 7411 has three three-input NAND gates
- D. 7400 has four two-input AND gates; 7411 has three three-input NAND gates Discuss
- 4. Assume a 4-bit ripple counter has a failure in the second flip-flop such that it "locks up." The third and fourth stages will ________.
Options- A. continue to count with correct outputs
- B. continue to count but have incorrect outputs
- C. stop counting
- D. turn into molten silicon Discuss
- 5. In a full-featured counter in HDL, the concept of rolling over simply means the count sequence has reached its limit and must start over at the beginning of the sequence.
Options- A. True
- B. False Discuss
- 6. What is unique about TTL devices such as the 74SXX?
Options- A. These devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn-on and turn-off times, which translates into higher frequency operation.
- B. The gate transistors are silicon (S), and the gates therefore have lower values of leakage current.
- C. The S denotes the fact that a single gate is present in the IC rather than the usual package of 2?6 gates.
- D. The S denotes a slow version of the device, which is a consequence of its higher power rating. Discuss
- 7. A macrofunction is a self-contained description of a logic circuit with all of its inputs, outputs, and operational characteristics defined.
Options- A. True
- B. False Discuss
- 8. Using the schematic diagram of a TTL NAND gate, determine the state of each transistor (ON or OFF) when all inputs are high.
Options- A. Q1-ON, Q2-OFF, Q3-ON, Q4-OFF
- B. Q1-ON, Q2-ON, Q3-OFF, Q4-OFF
- C. Q1-OFF, Q2-OFF, Q3-ON, Q4-ON
- D. Q1-OFF, Q2-ON, Q3-OFF, Q4-ON Discuss
- 9. The solution to the binary problem 00110110 ? 00011111 is 00011000.
Options- A. True
- B. False Discuss
- 10. As a technician you are confronted with a TTL circuit board containing dozens of IC chips. You have taken several readings at numerous IC chips, but the readings are inconclusive because of their erratic nature. Of the possible faults listed, select the one that most probably is causing the problem.
Options- A. A defective IC chip that is drawing excessive current from the power supply
- B. A solar bridge between the inputs on the first IC chip on the board
- C. An open input on the first IC chip on the board
- D. A defective output IC chip that has an internal open to Vcc Discuss
More questions
Correct Answer: XNOR
Correct Answer: False
Correct Answer: 7400 has four two-input NAND gates; 7411 has three three-input AND gates
Correct Answer: stop counting
Correct Answer: True
Correct Answer: These devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn-on and turn-off times, which translates into higher frequency operation.
Correct Answer: True
Correct Answer: Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
Correct Answer: False
Correct Answer: An open input on the first IC chip on the board
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