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## BSc.CSIT 1st Semester Old Questions

## Subject: Digital Logic

- Subject: Digital Logic
- BSc.CSIT 1st Semester Digital Logic Question Year : 2065
- Year : 2066 BSc.CSIT 1st Semester Digital Logic Old Question
- Year: 2067 Old Question of BSc.CSIT 1st Semester Digital Logic
- Year : 2068 Question of BSc.CSIT 1st Semester Digital Logic
- BSc.CSIT 1st Semester Digital Logic Question Year : 2069
- Year : 2070 BSc.CSIT 1st Semester Digital Logic Questions
- Year : 2071 Old Question of BSc.CSIT 1st Semester Digital Logic
- Year: 2072 1st Semester BSc.CSIT Digital Logic Old Questions
- Year: 2073 Old Questions of Digital Logic

BSc.CSIT 1st Semester Digital Logic

### BSc.CSIT 1st Semester Digital Logic Question Year : 2065

Long Questions:

Attempt any two questions: (2 × 10=20)

- Draw a block diagram, truth table and logical circuit of a 16 x 1 multiplexer and explain

its working principle. - Explain the 4-bit ripple counter and also draw a timing diagram.
- Design the full subtract or circuit with using Decoder and explain the working

principle.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Design a half adder logic circuit using only NOR gate.
- Convert the following decimal numbers into hexadecimal and octal number.

(a) 304

(b)224

- Describe the three-variable K-map with example.
- Design the Decoder using Universal gates.
- What is combinational logic? What are its important features?
- Describe the clocked RS flip-flop.

10.What do you mean by triggering of flip-flop? - What are the shift Register operations?
- Describe the Ripple counter.
- Write short notes on:

(a) Registers.

(b)Digital.

(c) EBCDIC.

### Year : 2066 BSc.CSIT 1st Semester Digital Logic Old Question

Long Questions:

Attempt any two questions: (2 × 10=20)

- Design the 4-bit synchronous up/down counter with timing diagram, logic diagram

and truth table. - Design a full subtractor with truth table and logic gates.
- Design a decimal adder with logical diagram and truth table.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Differentiate between Analog and Digital system.
- Convert the following octal numbers to hexadecimal.

a. 1760.46

b. 6055.263 - Which gates can be used as inverts in additional to the NOT gate and how?
- Draw a logic gates that implements the following

a) A = (Y1 ⊕ Y2) (Y3 ⊙ Y4

) + (Y5 ⊕ Y6 ⊕ Y7

)

b) A = (X1 ⊙ X2

) + (X3 ⊙ X4

) + ( X4 ⊙ X5

)⨁(X4 ⊙ X7

)

- State and prove De-Morgan’s theorem 1st and 2nd with logic gates and truth table.
- Reduce the following expressions using K-map

̅A + B(A + B + D)(B + C)(B + C + D)

10.Differentiate between a MUX and a DEMUX.

- Explain the operation of Decoder.
- What are the various types of shift registers?
- What do you mean by Synchronous counter?

### Year: 2067 Old Question of BSc.CSIT 1st Semester Digital Logic

Long Questions:

Attempt any two questions: (2 × 10=20)

- What is magnitude comparator? Design a logic circuit for a 4-bit magnitude

comparator and explain it. - What do you mean by full adder and full subtractor? Design a 3 to 8 line decoder using

two 2 to 4 line decoder and explain it. - What is JK master slave flip-flop? Design its logic circuit, truth table and explain the

working principle.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Convert the following hexadecimal number to decimal and octal numbers

a. 0FFF

b. 3FFF - Design a half adder logic circuit using NOR gates only.
- Proof the 1st and 2nd law of De Morgan’s theorems with logic gate and truth table.
- What do you mean by universal gate? Realize the following logic gates using NOR

gates.

a. OR gate

b. AND gate - Draw a logic circuit of 4×1 multiplexer.
- What is a flip-flop? Mention the application of flip-flop.

10.Explain the Ripple Counter. - Design the Decimal Adder.
- What do you mean by shift registers? Explain.
- Write short notes on (any two):

a. Decoder

b. Integrated circuit

c. PLA.

### Year : 2068 Question of BSc.CSIT 1st Semester Digital Logic

Long Questions:

Attempt any two questions: (2 × 10=20)

- Draw a block diagram truth table and logic circuit of 1*16 Demultiplexer and explain

its working principle. - Design a 3 bit synchronous counter and explain it.
- What is magnitude comparator? Design a logic circuit for 4 bit comparator and explain

it.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Design a half subtractor circuit using only NAND gates.
- Convert the following decimal numbers into Hexadecimal and Octal numbers:
- 504
- 250
- Design an encoder using universal gates.
- What do you mean by D-flip-flop?

10.What is sequential logic? What are the important features? - Simplify the Boolean function using K-Maps.
- F = X’yz + X’yz’ +Xy’z’ +Xy’z
- Draw a parallel-parallel-out shift register and explain it.

14.Explain the 4 bit ripple counter. - Explain the programmable logic array.

16.Write short notes on :

a. Asynchronous counter

b. Multiplexers

c. State reduction table

### BSc.CSIT 1st Semester Digital Logic Question Year : 2069

Long Questions:

Attempt any two questions: (2 × 10=20)

- What is decoder? Implement the following using decoder.

a. F (W X Y Z) = Σ (0,1,3,4,8,9,10)

b. F (W X Y Z) = Σ (1,3,5,6,11,13,14) - What do you mean by asynchronous counter? Design a mod-6 synchronous counter

using T flip-flops. - Explain the Master-slave S-R flip-flop with logic diagram, truth table and timing

diagram.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Design a half subtractor using only NOR gates.
- Convert the following decimal numbers into hexadecimal and octal number.

a. 220

b. 1020 - Design a multiplexer 4*1 using only universal gates.
- What is J-K flip flop? Explain.
- Write a procedure to reduce K-maps.
- What are the various types of shift registers?

10.Draw a logic diagram of a 4 bit ripple counter using D-flip flop. - Differentiate between combinational logic and sequential logic. List some

applications of sequential logic. - Explain the decimal adder.
- Write short notes on :

a. Programmable Logic Array

b. Triggering at flip-flop

c. Memory Unit

### Year : 2070 BSc.CSIT 1st Semester Digital Logic Questions

Long Questions:

Attempt any two questions: (2 × 10=20)

- Design Magnitude comparator and also design a logic diagram for a 4 bit magnitude

comparator. - What do you mean by ripple counters? Explain with timing diagram.
- Explain the full subtractor with using decoder.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Design a half adder logic using only NAND gates.
- Convert the following decimal number into hexadecimal and octal.

a. 334

b. 225 - Explain the K-map with three variables.
- Explain the combination logic with examples.
- Differentiate between Multiplexer and demultiplexer.
- Mention the difference types of shift register.

10.What do you mean by Ripple counters? - Explain the decoder and design with universal gates.
- What do you mean by clocked RS flip-flop ?Explain
- Write short note on (any two):

a) Flip flop

b) Synchronous Counter

c) Digital systems.

### Year : 2071 Old Question of BSc.CSIT 1st Semester Digital Logic

Long Questions:

Attempt any two questions: (2 × 10=20)

- What are the various types of numbering system use in the digital logic? Explain.

Convert the 3EC816 into different numbering system that you know. - Design the mod-6 asynchronous counter and explain with truth table.
- What is demultiplexer? Draw its block diagram and explain its working principle.

Short Questions:

Attempt any eight questions: (8 × 5=40)

- Convert the hexadecimal number 2BFC to binary and then to octal.
- Proof the De-Morgan 1st and 2nd theorem with truth table and logic gates.
- Simplify, the following Boolean function using three variable K-map.

a) F(X,Y,Z) = ∑(0,3,2,5)

b) F(A,B,C) = ∑(0,2,4,5,6) - Simplify the Boolean expression.

Y = ̅A̅̅.̅B̅ + A

̅̅̅̅+̅̅ B̅

prepare truth table to show that the simplified expression is correct or not?

- Explain the PLA (Programmable Logic Array).
- How JK flip flop can convert into a D-flip flop?
- What do you mean by synchronous counter? Explain with truth table.
- Draw a 3 to 8 decoder circuit and explain its operation.
- Mention the difference types of shift register and explain.
- Write short notes on:-

a) CMOS

b) Universal gates

c) Error detection code

### Year: 2072 1st Semester BSc.CSIT Digital Logic Old Questions

Long Questions:

Attempt any two questions: (2 × 10=20)

- Design and implement with logic diagram of synchronous 3 bit up down counter using

J-K flip flop. - Design a magnitude comparator using logic gates and truth table.
- Design a master-slave S-R flip flop with logic diagram and truth table.

Short Questions:

Attempt any eight questions: (8 × 5=40) - What do you mean by the Gray code? What are its application?
- Covert the following:

a) A08E. FA16 = (? )10

b) AE9. BOE16 = (? )2 - State and prove commutative laws, associative laws and distributive law using logic

gate and truth table. - Show that both NAND gate and NOR gate are universal gates.
- Prove that:

a) ABC ̅̅̅̅̅̅ ((A + B + C)

̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅)=ABC

b) A + B̅C(A + B̅ C

̅̅̅̅̅ = A - Reduce the following expression using K-map.

a) (A+B)(A+B̅+C)(A+C̅)

b) A+B(A+B̅+D)(B+C̅)(B+C+D) - How does a J-K flip flop differs from an S-R flip flop in its basic operations? Explain.
- Differentiate between a counter a shift register.
- Design a 4 input multiplexer using logic diagram and truth table.
- Explain the serial-In, parallel out shift register.

### Year: 2073 Old Questions of Digital Logic

Long Questions:

Attempt any two questions: (2 × 10=20)

- Explain the magnitude comparator and also design a logic diagram for 4 bit magnitude

comparator. - What do you mean by decoder? Design a 3 to 8 line decoder using 2 to 4 line decoder

and explain it. - What do you mean by ripple counter? Explain the design procedure of sequential

circuits.

Short Questions:

Attempt any eight questions: (8 × 5=40) - Convert the following hexadecimal number to decimal and octal numbers.

a) 4FF

b) 6FED - Explain the error detection code with example.
- Explain the duality theorem with example.
- Design half adder logic circuit using only universal gates.
- Draw a logic circuit of 8*1 multiplexer.
- Design the 4 bit parallel binary adder.

10.Explain the PLA with the block diagram. - Explain the R-S flip flop with truth table.
- Explain the shift register with example.
- Write short note on (any two):

a) Binary counter

b) State reduction

c) Negative edge triggering