Key Topic 35: Logic Levels

Question 1

3-35E1: In a negative-logic circuit, what level is used to represent a logic 0?

A. Low level.
B. Positive-transition level.
C. Negative-transition level.
D. High level.

Answer 1

D. High level.

Question 2

3-35E2: For the logic input levels shown in Figure 3E12, what are the logic levels of test points A, B, and C in this circuit? (Assume positive logic.)

A. A is high, B is low, and C is low.
B. A is low, B is high, and C is high.
C. A is high, B is high, and C is low.
D. A is low, B is high, and C is low.

Answer 2

B. A is low, B is high, and C is high.

Question 3

3-35E3: For the logic input levels given in Figure 3E13, what are the logic levels of test points, A, B, and C in this circuit? (Assume positive logic.)

A. A is low, B is low, and C is high.
B. A is low, B is high, and C is low.
C. A is high, B is high, and C is high.
D. A is high, B is low, and C is low.

Answer 3

C. A is high, B is high, and C is high.

Question 4

3-35E4: In a positive-logic circuit, what level is used to represent a logic 1?

A. High level.
B. Low level.
C. Positive-transition level.
D. Negative-transition level.

Answer 4

A. High level.

Question 5

3-35E5: Given the input levels shown in figure 3E14 and assuming positive logic devices, what would the output be?

A. A is low, B is high, and C is high.
B. A is high, B is high, and C is low.
C. A is low, B is low, and C is high.
D. None of the above are correct.

Answer 5

A. A is low, B is high, and C is high.

Question 6

3-35E6: What is a truth table?

A. A list of input combinations and their corresponding outputs that characterizes a digital device’s function.
B. A table of logic symbols that indicate the high logic states of an op-amp.
C. A diagram showing logic states when the digital device’s output is true.
D. A table of logic symbols that indicates the low logic states of an op-amp.

Answer 6

A. A list of input combinations and their corresponding outputs that characterizes a digital device’s function.