Logic Gates Questions and Answers

Answer: C

Correct answer: logic analyzer

A logic analyzer captures many digital lines at once and displays them as a timing diagram, which is what allows the actual waveforms to be compared with the expected ones. A DMM reads a single value and a spectrum analyzer works in the frequency domain.

Answer: B

Correct answer: 4 circuits

The prefixes count the independent gates in the package: dual two, triple three, quad four, hex six. A quad two-input NAND, the 7400, holds four separate gates.

Answer: A

Correct answer: A = 0, B = 0, C = 0

An OR gate is LOW only when every input is LOW; a single 1 makes the output 1.

Answer: C

Correct answer: OR

In Boolean algebra the plus sign denotes OR and the dot, or juxtaposition, denotes AND. Complementation is written with a prime or an overbar.

Answer: C

Correct answer: AND gate

An AND gate outputs 0 whenever any input is 0, since it needs all of them to be 1. An OR gate would be LOW only if every input were 0.

Answer: B

Correct answer: 16

The 4049 is a hex inverting buffer, and its package has 16 pins - six inverters using twelve pins, plus supply and ground, with two pins unused.

Answer: A

Correct answer: basic gates, a clock oscillator, and a repetitive waveform generator

The minimum set is a clock to provide timing, a repetitive waveform generator such as a counter to divide that clock into a sequence, and basic gates to decode the sequence into the particular waveform wanted. The option adding a Johnson counter as well goes beyond the minimum, which is what the question asks for.

Answer: D

Correct answer: 5-volt supply

TTL is specified for a nominal 5 V supply, with LOW below about 0.8 V and HIGH above about 2 V.

Answer: D

Correct answer: all inputs are LOW

NOR is the complement of OR, and OR is 0 only when every input is 0, so NOR is 1 in exactly that case.

Answer: A

Correct answer: competitive with TTL

Early CMOS was markedly slower than TTL, but successive process improvements have brought its switching speed to roughly the same level, which is why CMOS has taken over while keeping its advantage in power.