Programmable Logic Device MCQs

Question 1

A(n) ________ one-shot starts a pulse in response to a trigger and will restart the internal pulse timer every time a subsequent trigger edge occurs before the pulse is complete.

Accepted Answer

retriggerable

Answer

non-retriggerable

Answer

high-level triggered

Answer

edge-triggered

Question 2

Assume you want to determine the timing diagram for a 4-bit counter using an oscilloscope. The best choice for an oscilloscope trigger signal is ________.

Accepted Answer

the clock signal

Answer

the most significant bit (MSB)

Answer

the least significant bit (LSB)

Answer

from a composite of the MSB and LSB

Question 3

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 ________.

Accepted Answer

stop counting

Answer

continue to count with correct outputs

Answer

continue to count but have incorrect outp

Answer

turn into molten silicon

Question 4

In order to use a shift register as a counter, ________.

Accepted Answer

the serial output of the register is connected back to the serial input of the register

Answer

the register's serial input is the counter input and the serial output is the counter output

Answer

the parallel inputs provide the input signal and the output signal is taken from the serial data output

Answer

serial in/serial out register must be used

Question 5

In order to check the CLR function of a counter, ________.

Accepted Answer

apply the active level to the CLR input and check all of the Q outputs to see if they are all in their reset state

Answer

ground the CLR input and check to be sure that all of the Q outputs are LOW

Answer

connect the CLR input to Vcc and check to see if all of the Q outputs are HIGH

Answer

connect the CLR to its correct active level while clocking the counter; check to make sure that all of the Q outputs are toggling

Question 6

A 4-bit binary up counter has an input clock frequency of 20 kHz. The frequency of the most significant bit is ________.

Accepted Answer

1.25 kHz

Answer

2.50 kHz

Answer

160 kHz

Answer

320 kHz

Question 7

Modulus refers to ________.

Accepted Answer

the maximum number of states in a counter sequence

Answer

a method used to fabricate decade counter units

Answer

the modulus of elasticity, or the ability of a circuit to be stretched from one mode to another

Answer

an input on a counter that is used to set the counter state, such as UP/DOWN

Question 8

A sequential circuit design is used to ________.

Accepted Answer

count in a random order

Answer

count up

Answer

count down

Answer

decode an end count

Question 9

The MOD-10 counter is also referred to as a ________ counter.

Accepted Answer

decade

Answer

strobing

Answer

BCD

Answer

circuit