# Digital Circuits Questions and Answers – Counters

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Counters”.

1. In digital logic, a counter is a device which ____________
a) Counts the number of outputs
b) Stores the number of times a particular event or process has occurred
c) Stores the number of times a clock pulse rises and falls
d) Counts the number of inputs

Explanation: In digital logic and computing, a counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal.

2. A counter circuit is usually constructed of ____________
a) A number of latches connected in cascade form
b) A number of NAND gates connected in cascade form
c) A number of flip-flops connected in cascade
d) A number of NOR gates connected in cascade form

Explanation: A counter circuit is usually constructed of a number of flip-flops connected in cascade. Preferably, JK Flip-flops are used to construct counters and registers.

3. What is the maximum possible range of bit-count specifically in n-bit binary counter consisting of ‘n’ number of flip-flops?
a) 0 to 2n
b) 0 to 2n + 1
c) 0 to 2n – 1
d) 0 to 2n+1/2

Explanation: The maximum possible range of bit-count specifically in n-bit binary counter consisting of ‘n’ number of flip-flops is 0 to 2n-1. For say, there is a 2-bit counter, then it will count till 22-1 = 3. Thus, it will count from 0 to 3.

4. How many types of the counter are there?
a) 2
b) 3
c) 4
d) 5

Explanation: Counters are of 3 types, namely, (i)asynchronous/synchronous, (ii)single and multi-mode & (iii)modulus counter. These further can be subdivided into Ring Counter, Johnson Counter, Cascade Counter, Up/Down Counter and such like.

5. A decimal counter has ______ states.
a) 5
b) 10
c) 15
d) 20

Explanation: Decimal counter is also known as 10 stage counter. So, it has 10 states. It is also known as Decade Counter counting from 0 to 9.
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6. Ripple counters are also called ____________
a) SSI counters
b) Asynchronous counters
c) Synchronous counters
d) VLSI counters

Explanation: Ripple counters are also called asynchronous counter. In Asynchronous counters, only the first flip-flop is connected to an external clock while the rest of the flip-flops have their preceding flip-flop output as clock to them.

7. Synchronous counter is a type of ____________
a) SSI counters
b) LSI counters
c) MSI counters
d) VLSI counters

Explanation: Synchronous Counter is a Medium Scale Integrated (MSI). In Synchronous Counters, the clock pulse is supplied to all the flip-flops simultaneously.

8. Three decade counter would have ____________
a) 2 BCD counters
b) 3 BCD counters
c) 4 BCD counters
d) 5 BCD counters

Explanation: Three decade counter has 30 states and a BCD counter has 10 states. So, it would require 3 BCD counters. Thus, a three decade counter will count from 0 to 29.

9. BCD counter is also known as ____________
a) Parallel counter
c) Synchronous counter
d) VLSI counter

Explanation: BCD counter is also known as decade counter because both have the same number of stages and both count from 0 to 9.

10. The parallel outputs of a counter circuit represent the _____________
a) Parallel data word
b) Clock frequency
c) Counter modulus
d) Clock count

Explanation: The parallel outputs of a counter circuit represent the clock count. A counter counts the number of times an event takes place in accordance to the clock pulse.

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