## Previous Year’s Question Papers of Digital Electronics & Computer Organisation

BCA second semester  Digital Electronics & Computer Organisation Last year’s question paper of Chaudhary Charan Singh University (ccsu)

## BCA Question Paper of Digital Electronics & Computer Organisation, 2015 (ccsu)

Digital Electronics & Computer Organisation (BCA-204)

TIME: THREE HOURS MAXIMUM MARKS : 75

Note: Attempt all the sections as per instructions

Section-A

Note: Attempt all the five questions. Each question carries 3 marks. very short answer is required not exceeding 75 words.

1. What is logic Gate? Explain logic designation.
2. Define the NAND and NOR gates through their truth tables.
3. Design a half adder using only NOR gates.
4. What is Multiplexer?
5. List of four basic flip-flop applications.

Section-B

Note: Attempt any two questions out of the following three questions, Each question carries 7.5 marks. Short answer is required not exceeding 200 words

1. Minimise the Boolean function
• Y(A,B,C)=A’ B’ C’+A’ B C’+A B’ C’+A B C’
2. Draw a full adder circuit using NAND gates only. Explain the functioning of the circuit and show that the output is that of full adder.
3. Draw the basic circuit of a ROM cell and Explain its working.

Section-C

Note: Attempt any three questions out of the following five Question. Each question carries 15 marks. Answer is required in detail.

• Explain the difference between primary and secondary memories.
• Implement the following function using 4 to 1 multiplexer.
• Explain how a J-K flip-flop can be converted into D flip-flop.
• Draw the logic diagram of a master-slave D flip-flop using NAND gates.
1. Explain the operation of a bi-directional shift register.
2. Explain the operation of a twisted ring counter and give its state diagram.
1. Draw and explain the working of three-bit asynchronous counter.
2. Prove the following identities.
• AB+ABC+A’B+AB’C = B+ AC
1. write a short note on cache memory organisation.

## BCA Question Paper of Digital Electronics & Computer Organisation, 2016 (ccsu)

Digital Electronics & Computer Organisation (BCA-204)

TIME: THREE HOURS MAXIMUM MARKS : 75

Note: Attempt all the sections as per instructions

Section-A

Note: Attempt all the five questions. Each question carries 3 marks. very short answer is required not exceeding 75 words.

1. What are the logic gates? Draw the schematic block diagram of a 3 input and gate. Give its truth table.
2. What is decoder and encoder?
3. What do you mean by cache memory?
4. What is the function of a shift-register? where are such register used?
5. Differentiate RAM and ROM?

Section-B

Note: Attempt any two questions out of the following three questions, Each question carries 7.5 marks. Short answer is required not exceeding 200 words.

1. Draw k map and simplify the following Boolean expression.
• Y(A,B,C,D)=Σ(0,2,4,6,8,10,12,14,15).
2. What is shortcoming of a S-R flip-flop? Explain how its shortcoming is removed by J-K flip-flop. Describe its operating principle.
3. Explain the difference between static and dynamic memories.

Section-C

Note: Attempt any three questions out of the following five Question. Each question carries 15 marks. Answer is required in detail.

1. Explain the various boolean and simplify the following boolean expressions.
• (A’+B’+B’A)D.
• A’BC’+ABC’+A’B’C’+A B’C’.
• A’BC’+A’BC’D+BC’.
• Implement a full-subtractor with two half-subtractors and an OR gate.
• Show how a full-adder can be converted to a full-subtractor with the additional of one inverter circuit.
2. Write short notes on the following.
• EPROM.
• Dynamic Ram.
• Hard disk.
• Floppy disk.
• CD-ROM.
3. Discuss the working principle of a synchronous (parallel) counter with its block diagram. What is the advantage of synchronous counter over asynchronous (ripple) counter? Give some examples of both type of counters.
4. what is associative memory? Draw and explain its block diagram. How read operations and write operation performed in the associated memories?

## BCA Question Paper of Digital Electronics & Computer Organisation, 2017 (ccsu)

Digital Electronics & Computer Organisation (BCA-204)

TIME: THREE HOURS MAXIMUM MARKS : 75

Note: Attempt all the sections as per instructions

Section-A

Note: Attempt all the five questions. Each question carries 3 marks. very short answer is required not exceeding 75 words.

1. What is truth table? What is its significance?
2. What is multiplexers?
3. Explain the Edge Triggered D flip-flops.
4. Why are NAND and NOR gates more popular?
5. Difference between registers and counters.

Section-B

Note: Attempt any two questions out of the following three questions, Each question carries 7.5 marks. Short answer is required not exceeding 200 words

1. Reduce the following Boolean expression using k-map?
2. The 2732 is a 4096 * 8 EPROM. How many address lines does it have?
3. Draw the master-slave JK flip-flop and explain its working.

Section-C

Note: Attempt any three questions out of the following five Question. Each question carries 15 marks. Answer is required in detail.

• Explain the difference between Cache memory and virtual memory.
• Draw the half adder logic circuit and summarise the operation.
• State the verify the De-Morgan’s law in the following Boolean Algebra.
• Draw a logic circuit diagram for the Boolean expression.
• Explain the operation of the bi-directional shift register.
• Explain how a JK flip-flop can be converted into a D flip-flop.
1. Define the following:
• Multiplexer (8 * 1) MUX design.
• Register.
• Flip-Flop applications.
• asynchronous counter.
• Basic cell of static RAM.
2. Write a short note on cache memory organisation.