Here are 1000 MCQs on Switching Circuits and Logic Design (Chapterwise).
1. Switches connected in parallel represent which operation?
a) NOT
b) AND
c) OR
d) NAND
View Answer
Explanation: Switches connected in parallel represent OR operation, because if any one or more of the switches are closed the current flows.
2. What is the primary function of a switching circuit in digital logic design?
a) Signal switching
b) Signal processing
c) Signal modulation
d) Signal amplification
View Answer
Explanation: Switching circuits in digital logic are designed to control the flow of signals, allowing the selection and manipulation of digital data by facilitating the switching between different paths.
3. What on the FlipFlop symbol identifies it as a positive edge triggered one?
a) Arrowhead with bubble on the clock input
b) Arrowhead on the clock input
c) Plus sign
d) Clk
View Answer
Explanation: The arrowhead symbol on the FlipFlop identifies it as a positive edge triggered one, since there is no bubble. The output of a positive edge triggered flipflop changes when the clock signal rises from 0 to 1.
4. Which counter counts both increments and decrements?
a) UpDown Counter
b) Ring Counter
c) Down Counter
d) Up Counter
View Answer
Explanation: In an UpDown counter, both the outputs of the flipflops, Q and Q’ are used as the input to the next flipflop and they are selected according to the operation. The selection operation is done by using AND gates. AND gates used for Up operation, take a signal named UPCOUNT and Q from flipflop as inputs. Similarly, AND gates used for Down operation, takes a signal named DOWNCOUNT and Q’ from flipflop as inputs. Preferred signal is kept high according to Up/Down operation while the other is kept low.
5. How can we classify a sequence generator circuit?
a) A parity checker
b) A general sequential circuit
c) A clocked Moore circuit
d) A clocked Mealy circuit
View Answer
Explanation: A sequence detector detects a specific sequence of bits present in a bit stream. For that the output at every state depends on the input and the present state of flipflops used that is the main characteristic of a clocked Mealy circuit. Hence the right answer is a clocked Mealy circuit.
6. Which of the following is an example of an iterative circuit?
a) Half adder
b) Comparator
c) ROM
d) Full adder
View Answer
Explanation: An iterative circuit performs the same operation on each pair of input bits which is necessary for a comparator circuit. For each iteration, a pair of bit will be compared. But the others like ROM, half or full adder don’t need any type of iterations. Hence, Comparator is the right answer.
7. Which of the following is used to code in a CPLD designing procedure?
a) Python
b) C++
c) VHDL
d) Assembly
View Answer
Explanation: CPLD means Complex Programmable Logic Devices. This has a complexity between PLAs and FPGAs. CPLDs are Complex Program Logic Devices those contain several macrocells grouped into a number of blocks. The design is first coded in HDL (Verilog or VHDL), once the code is validated (simulated and synthesized).
8. Which one of the following best describes a sequential machine?
a) A mathematical model
b) A logic circuit
c) A Moore machine
d) An electronic circuit
View Answer
Explanation: A sequential machine is a mathematical model of a certain type sequential circuit, which has inputs and outputs that can each take on any value from a finite set and are at interest only at certain instants of time. Output depends on both the current as well as the previous input.
9. 10. What are the possible values of the STD_LOGIC data type?
a) 0, 1, 2
b) X, 0, 1, Z
c) 0, 1
d) o to 9
View Answer
Explanation: Data types are used in VHDL to define variables of a specific types. The STD_LOGIC data type can have 4 values – X, 0, 1 and Z. It can have other values also but they are not synthesizable – i.e. they cannot be implemented on CPLDs and FPGAs.
10. What is the characteristic feature of a flipflop in sequential logic circuits?
a) Amplification
b) Feedback
c) Delay
d) Memory
View Answer
Explanation: Flipflops in sequential logic circuits store binary information, providing a memory element for the system.
Chapterwise Multiple Choice Questions on Switching Circuits and Logic Design
 Boolean Algebra
 Introduction to VHDL
 Latches and FlipFlops
 Registers and Counters
 Analysis of Clocked Sequential Circuits
 Derivation of State Graphs and Tables
 Reduction of State Tables State Assignment
 Sequential Circuit Design
 VHDL for Sequential Logic
1. Switching Circuits MCQs on Boolean Algebra
The section contains multiple choice questions and answers on boolean algebra basic operations and theorems, boolean expressions and truth tables, boolean laws like commutative, associative and demorgan’s laws, multiplying out and factoring, boolean expressions complementing, exclusiveor and equivalence operations.
2. Logic Design MCQ on VHDL
The section contains questions and answers on combinational circuits vhdl description, multiplexers vhdl models, vhdl modules, vhdl signals, constants and arrays, vhdl operators, packages, libraries and ieee standard logic.


3. Latches and FlipFlops
The section contains MCQs on setreset latch, gated latches, flip flops like sr flip flop, jk flip flop, t flip flop and edgetriggered d flip flop.


4. Logic Design Questions on Registers and Counters
The section contains multiple choice questions and answers on registers, register transfers, binary counters design, other sequences counters, counter designs using sr and jk flip flops.


5. Analysis of Clocked Sequential Circuits
The section contains Logic Design questions and answers on sequential parity checker, signal tracing and timing charts analysis, sequential circuits models, state tables and graphs.


6. Logic Design MCQs on Derivation of State Graphs and Tables
The section contains MCQs on sequence detector design and serial data code conversion


7. Reduction of State Tables State Assignment
The section contains multiple choice questions and answers on redundant states elimination, equivalent states, onehot state assignment, equivalent sequential circuits and state assignments.


8. Sequential Circuit Design
The section contains questions and answers on code converters, iterative circuits design, sequential circuits design using roms, plas, cplds and fpgas, computeraided design overview, sequential circuits simulation and testing.
9. VHDL for Sequential Logic
The section contains Sequential Logic Design MCQs on modeling flip flops using vhdl processes, registers and counters modeling using vhdl processes, sequential machine modeling, combinational logic modeling using vhdl processes, vhdl code synthesis, processes and sequential statements.
Wish you the best in your endeavor to learn and master Switching Circuits and Logic Design!
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