# DECO Previous year Paper

### B.C.A. (Second Semester)Examination, 2016

(Digital Electronics & Computer Organization)

Time: Three Hours                                          Maximum Marks: 75

Note: Attempt any five questions. All question carry equal marks. The answer to short questions should not exceed 200 words and the answer to long answer type questions should not exceed 500 words.

1. (A) Show that NAND gate is a universal gate.

(B) What is the basic dunction of a decoder? Explain basic 3- input decoder with diagram.

2. Describe the mode of working of an edge triggered S-R flip flop.

3. What do you understand by virtual memory? Explain the basic organization and working methodology of virtual memory.

4.(A) Using the Karnaugh Map Method. Minimize the expression:

X = A B C  +  A B C   +   A B C  + A B C

(B) What are “ Don’t Care Conditions”? Discuss how they are handled, with the help of an example.

5. Using the postulates of Boolean Algebra, simplify the following expression:

•            (i)          A B + A ( B + C ) + B ( B + C )
•            (ii)          A B ( C + B D ) + A B
•            (iii)          A B C + ( A + B + C ) A B C D
•            (iv)          A B + A B C + B C D + B E

6. Describe the working of Ripple counter with the suitable diagram and counting sequence. How is the Ripple counter used in digital circuit?

7. Distinguish between:

A) Combinational and sequential Circuits

B) Synchronous and Asynchronous counter

C) T flip flop and D flip flop

Give suitable diagram where necessary.

8. What is a shift register? Discuss the different methods of operation of shift register with clear diagram. Mention the used of shift Register in computer hardware circuit.

### B.C.A. (Second Semester)Examination, 2017

(Digital Electronics & Computer Organization)

Time: Three Hours                                          Maximum Marks: 75

Note: Attempt any five questions. All question carry equal marks. The answer to short questions should not exceed 200 words and the answer to long answer type questions should not exceed 500 words.

1. (A) Draw the Truth Table and the symbol for the following gates:
2. XNOR
3. NAND
4. XOR

(B) Which gates is know as the “Agreement Gate”? why?

(C) Explain the working of any one of the following:

(i)         Decoder

(ii)         Multiplexer

2.(A)  Describe the working of full adder with the help of clear  circuitDiagram and truth table.

(B)  Differentiate between :

(i)     Combinational and Sequential Circuits

(ii)     Decoder and Encoder

3.Write an explanatory not on the following:

• EPROM
• CD-ROM

4.Describe the working of a Master-Slave J-K flip flop with the help of clear Block diagram and state table. Explain the “Race-around condition” and discuss how the master-slave setup circumvents it?

5. (A) What is cache memory? Explain.

(B) How does the cache memory improve the throughput of a digital computer?

(C) How many types of cache memories are available? Compare their relative merits and demerits.

6. Write short notes on:

(A) RAM banking

(B) Associate memory

7. Define and explain with example:

(A) Don’t care condition.

(B) Associate and distributive laws of Boolean Algebra

(C) Min Term and Max Term

8.  Differentiate between the following :

(A)  Edge triggered and Pulse Triggered Flip Flop

(B)  Binary code and BCD code

(C)  SIPO and PISO shift register.

### B.C.A. (Second Semester)Examination, 2019

(Digital Electronics & Computer Organization)

Time: Three Hours                                          Maximum Marks: 75

Note: Attempt any five questions. All question carry equal marks. The answer to short questions should not exceed 200 words and the answer to long answer type questions should not exceed 500 words.

1.Explain the following with example (any three):

(i)Mutliplexer                                    (ii) SOP and POS

(iii) Don’t care states                       (iv) Universal Gate

2. How is a RAM constructed? Discuss  the different technology used in constructing the RAM of a computer, with their relative advantages and disadvantages.

3. (A) explain with formula, the De Morgan’s Laws. Prove them with the help of truth table .

(B) prove the following Boolean identities:

(i)          AB + AB + A B = (A + B )

(ii)        [ (A+B) + (A+B) ]’ = A B + A +B

(iii)      ( A + B ) ( A+ B ) = A B + A B

(iv)       A + A B C = A + B C

4. (A) realize a three-input gate using two-input gates for the following gates :

(i) AND          (ii) OR           (iii) NAND           (iv) NOR

(B) Consider the expression:

Z = A + B + C + D ………

Show that Z = 1 for an odd number of variable are 1 and

Z = 0 if an even number of variable are 1.

5. (i) Describe and discuss the operation of a T-type Flip flop.

(ii) Design a 3-bit UP/DOWN counter with the help of J-K flops.

6. Explain with diagram:

(i) PROM          (ii) EPROM          (iii) CD-ROM          (iv) Hard disk

7. (A) Minimize the given Boolean function using K-maps and implement the simplified function using NAND gates only.

F ( A,B,C,D )=    m (0,1,2,9,11,15) + d (8,10,14)

8. explain briefly :

(A) Race Around condition and its solution

(B) D Flip Flop using NAND gates.