## University of Madras

Chepauk, Chennai-600 005.

**Digital Logic Fundamentals**

**Subject Code: SAU1A****Year : First**

**Semester: I****Time: Three hours**

Month & Year of Examination: NovemberMonth & Year of Examination: November

**- 2012****SECTION A - (10 * 2 = 20 marks)**

**Answer any TEN questions.**

**All questions carry equal marks.**

**Each answer should not exceed 30 words.**

**1. Define: Complement Numbers.**

2. What is meant by translator?

3. What is the base of the number system?

4. Draw the symbols of basic logic gates.

5. Expand ASCII and EBCDIC

6. Define four variable karanugh map.

7. What is meant by synchronous counter.

8. What is flip flop?

9. What is meant by registers? Give any two examples.

10. What is PLA?

11. What is meant by Encoder?

12. Define Main Memory?

2. What is meant by translator?

3. What is the base of the number system?

4. Draw the symbols of basic logic gates.

5. Expand ASCII and EBCDIC

6. Define four variable karanugh map.

7. What is meant by synchronous counter.

8. What is flip flop?

9. What is meant by registers? Give any two examples.

10. What is PLA?

11. What is meant by Encoder?

12. Define Main Memory?

**SECTION B - (5 * 5 = 25 marks)**

**Answer any FIVE questions.**

**All questions carry equal marks**

**Each answer should not exceed 200 words.**

**13. Explain the characteristics of computer.**

14. Convert the following

(a) (127.85) = (?)

10 10

(b) (175.165) = (?)

8 10

15. Discuss the basic theorems of Boolean Algebra.

16. Explain the principles of master slave flip flop using logic

14. Convert the following

(a) (127.85) = (?)

10 10

(b) (175.165) = (?)

8 10

15. Discuss the basic theorems of Boolean Algebra.

16. Explain the principles of master slave flip flop using logic

**circuit.**

17. Explain the design of decoders with diagram.

18. Explain a 1 * 16 bit multiplexer with truth table.

19. Explain the ASCII and Gray code with example.

17. Explain the design of decoders with diagram.

18. Explain a 1 * 16 bit multiplexer with truth table.

19. Explain the ASCII and Gray code with example.

**SECTION C - (3 * 10 = 30 marks)**

**Answer any THREE questions.**

**All questions carry equal marks.**

**Each answer should not exceed 500 words.**

**20. Explain the following**

(a) Computer languages

(b) Operating systems.

21. Explain the universal logic gates with truth table.

22. Minimize four variables Boolean equation using K-map

(a) Computer languages

(b) Operating systems.

21. Explain the universal logic gates with truth table.

22. Minimize four variables Boolean equation using K-map

**method and implement it using NAND gates.**

**F = WXYZ + WXYZ + WXYZ + WXYZ**

23. Describe the design of the synchronous counter and

23. Describe the design of the synchronous counter and

**explain with truth table.**

24. Design the logic diagram of adder and subtractor with truth

24. Design the logic diagram of adder and subtractor with truth

**table.**

**Month & Year of Examination:**

**APRIL - 2012**SECTION A -(10x2=20 marks)

Answer any TEN questions.

All questions carry equal marks

1. What are the different categories of computers?

2. What is a compiler?

3. What is the decimal equivalent of 10111.

4. Expand ASCII and EBCDIC.

5. Define Boolean Algebra.

6. Write the Associative and Distributive laws.

7. Define demultiplexer.

8. Draw the logic diagram and its truth table of half adder.

9. What is scratch pad memory?

10. List any six operations generated in the ALU.

11. List the six phases of the computer design process.

12. What is PLA?

SECTION B - (5 x 5=25 marks)

Answer any FIVE questions.

All questions carry equal marks

13. Explain the different types of computers.

14. Convert the decimal numbers to the base indicated.

(a) 175 to octal

(b) 2479 to hexadecimal

(c) 255 to binary.

15.Explain the binary logic with symbols and truth tables.

16. Explain JK Master Slave flip flop.

17. Explain the operation of clocked RS flip flop.

18. Describe in detail the functional units of a digital computer with a neat block diagram.

19. Describe the PLA control method of designing a control unit.

SECTION C -(3x10=30 marks)

Answer any THREE questions.

All questions carry equal marks

20. Discuss about generation of computers.

21. Discuss about Gray, Excess 3 and error detection codes with an example.

22. Using maps derive minimal product of sums expression for the function in four variables w, x, y, z:

m1+m3+m5+m7+m12+m13+m8+m9.

23. Explain the operation of digital multiplexers and show

how it can be used to implement any Boolean function.

24. Describe in detail how the arithmetic and logic unit of a computer is designed.

Answer any TEN questions.

All questions carry equal marks

1. What are the different categories of computers?

2. What is a compiler?

3. What is the decimal equivalent of 10111.

4. Expand ASCII and EBCDIC.

5. Define Boolean Algebra.

6. Write the Associative and Distributive laws.

7. Define demultiplexer.

8. Draw the logic diagram and its truth table of half adder.

9. What is scratch pad memory?

10. List any six operations generated in the ALU.

11. List the six phases of the computer design process.

12. What is PLA?

SECTION B - (5 x 5=25 marks)

Answer any FIVE questions.

All questions carry equal marks

13. Explain the different types of computers.

14. Convert the decimal numbers to the base indicated.

(a) 175 to octal

(b) 2479 to hexadecimal

(c) 255 to binary.

15.Explain the binary logic with symbols and truth tables.

16. Explain JK Master Slave flip flop.

17. Explain the operation of clocked RS flip flop.

18. Describe in detail the functional units of a digital computer with a neat block diagram.

19. Describe the PLA control method of designing a control unit.

SECTION C -(3x10=30 marks)

Answer any THREE questions.

All questions carry equal marks

20. Discuss about generation of computers.

21. Discuss about Gray, Excess 3 and error detection codes with an example.

22. Using maps derive minimal product of sums expression for the function in four variables w, x, y, z:

m1+m3+m5+m7+m12+m13+m8+m9.

23. Explain the operation of digital multiplexers and show

how it can be used to implement any Boolean function.

24. Describe in detail how the arithmetic and logic unit of a computer is designed.

**Month & Year of Examination**

**November & 2011****SECTION A - (10 * 2 = 20 marks)**

**Answer any TEN questions.**

**All questions carry equal marks.**

**Each answer should not exceed 30 words.**

1. Convert the following hexadecimal numbers into binary numbers:

1. Convert the following hexadecimal numbers into binary numbers:

**(a) FFFF**

**(b) AAAA**

2. State Commutative law.

3. Write the truth table for NAND gate.

4. Define Flip-flop.

5. What is Memory?

6. What is Bit?

7. What is the 2s complement of (111111)?

8. What is called as LSB?

9. Mention the types of level triggering in flip-flop.

10.What do you mean by maxterm?

11.Define Gate.

12.What is the function of shift register.

2. State Commutative law.

3. Write the truth table for NAND gate.

4. Define Flip-flop.

5. What is Memory?

6. What is Bit?

7. What is the 2s complement of (111111)?

8. What is called as LSB?

9. Mention the types of level triggering in flip-flop.

10.What do you mean by maxterm?

11.Define Gate.

12.What is the function of shift register.

**SECTION B - (5 * 5 = 25 marks)**

**Answer any FIVE questions.**

**All questions carry equal marks.**

**Each answer should not exceed 200 words.**

13. Express the following functions in canonical SOP form

13. Express the following functions in canonical SOP form

**Y = A +BC**

14. Discuss in detail about the Demorgans theorems.

15. Discuss in detail about the Full adder.

16. Add the numbers -5 and -2 using 2s compliment method. Assume 4-bit word register.

17. Draw the diagram of D flip-flop and explain its function.

18. Multiply (11011)2 by (101)2

19. Solve the following Binary numbers into its equivalent Octal and Hexadecimal Numbers:

14. Discuss in detail about the Demorgans theorems.

15. Discuss in detail about the Full adder.

16. Add the numbers -5 and -2 using 2s compliment method. Assume 4-bit word register.

17. Draw the diagram of D flip-flop and explain its function.

18. Multiply (11011)2 by (101)2

19. Solve the following Binary numbers into its equivalent Octal and Hexadecimal Numbers:

**(a) (101011)2**

**(b) (11011110)2**

**SECTION C - (3 * 10 = 30 marks)**

**Answer any THREE questions.**

**All questions carry equal marks.**

**Each answer should not exceed 500 words.**

20. Explain the Master-Slave operation of the JK flip flop with

20. Explain the Master-Slave operation of the JK flip flop with

**neat diagram.**

21. Discuss in details about the different types of counters.

22. Explain Mod-10 counter with neat diagram.

23. What is universal building block? Explain.

24. Explain RS flip flop and T flip flop with truth tables.

21. Discuss in details about the different types of counters.

22. Explain Mod-10 counter with neat diagram.

23. What is universal building block? Explain.

24. Explain RS flip flop and T flip flop with truth tables.

**Month & Year of Examination**

**November & 2009** PART A - (10 x 3 = 30 marks)

Answer any TEN questions.

All questions carry equal marks.

1.Convert decimal 0.6875 to binary.

2. Use 2's complement to perform M-N with the given binary number M = 1010100 N = 1000100

3.Write a note on "Error-Detection Codes".

4.Prove: x + x = x .

5.Construct the truth table for F = xy’ + x ' y .

6. Draw the logic F = x' y’ z + x 'y z + xy’ circuit for the expression

7. Give the logic diagram and graphic symbol for clocked RS flip-flop.

8.What are the functions of counter?

9.Describe the use of encoders.

10.What are Demultiplexers?

11.What is meant by accumulator?

12.Explain 'Minterms' with an example.

PART B - (5 x 6 = 30 marks)

Answer any FIVE questions.

All questions carry equal marks.

13.Write short notes on "Logic Gates".

14.Simplify the Boolean function using map method F =A'C+A'B+AB'C+BC

15.Explain the operations of status registers.

16. What is a decoder? Draw the logic diagrams of a BCD to decimal decoder and explain.

17. Explain with a logic diagram, the working of a full-adder.

18. Describe the operation of accumulator with neat diagram.

19. Describe about alphanumeric codes and error codes.

PART C - (4 x 10 = 40 marks)

Answer any FOUR questions.

All questions carry equal marks.

20.Perform the following in binary form.

(a) (128)10 - (64)10 (b) (l02)10 + (120)10 (c) (31)10 X (14)10 (d) (25)10 / (5)10

21Prove the following equations:

(a) (X+Y)(X+Z)=X+YZ (b) (A +B’+C)(A +B’+C’)(A +B +C) =A +B’ C.

22. Explain the shift-right register and shift-left register with circuit diagram and truth tables.

23. Draw the block diagram of a ripple counter. Explain its operation. What is the advantage of a synchronous

counter over ripple counter?

24. Explain the action of multiplexer and demultiplexer with suitable diagrams.

25.Describe the operation with function table of ALU

Answer any TEN questions.

All questions carry equal marks.

1.Convert decimal 0.6875 to binary.

2. Use 2's complement to perform M-N with the given binary number M = 1010100 N = 1000100

3.Write a note on "Error-Detection Codes".

4.Prove: x + x = x .

5.Construct the truth table for F = xy’ + x ' y .

6. Draw the logic F = x' y’ z + x 'y z + xy’ circuit for the expression

7. Give the logic diagram and graphic symbol for clocked RS flip-flop.

8.What are the functions of counter?

9.Describe the use of encoders.

10.What are Demultiplexers?

11.What is meant by accumulator?

12.Explain 'Minterms' with an example.

PART B - (5 x 6 = 30 marks)

Answer any FIVE questions.

All questions carry equal marks.

13.Write short notes on "Logic Gates".

14.Simplify the Boolean function using map method F =A'C+A'B+AB'C+BC

15.Explain the operations of status registers.

16. What is a decoder? Draw the logic diagrams of a BCD to decimal decoder and explain.

17. Explain with a logic diagram, the working of a full-adder.

18. Describe the operation of accumulator with neat diagram.

19. Describe about alphanumeric codes and error codes.

PART C - (4 x 10 = 40 marks)

Answer any FOUR questions.

All questions carry equal marks.

20.Perform the following in binary form.

(a) (128)10 - (64)10 (b) (l02)10 + (120)10 (c) (31)10 X (14)10 (d) (25)10 / (5)10

21Prove the following equations:

(a) (X+Y)(X+Z)=X+YZ (b) (A +B’+C)(A +B’+C’)(A +B +C) =A +B’ C.

22. Explain the shift-right register and shift-left register with circuit diagram and truth tables.

23. Draw the block diagram of a ripple counter. Explain its operation. What is the advantage of a synchronous

counter over ripple counter?

24. Explain the action of multiplexer and demultiplexer with suitable diagrams.

25.Describe the operation with function table of ALU

**Month & Year of Examination**

**November & 2006****PART A - [5 x 8 = Marks 40]**

Answer any FIVE questions.

All questions carry equal marks.

Answer any FIVE questions.

All questions carry equal marks.

**1. Convert the following numbers as directed.**

(a) (345.625)10 into its binary equivalent (b) (FED)16 into its decimal equivalent.

2. Reduce the following Boolean expressions into its minimal form:

(a) W(K,L,M)=KL+LM+KM (b) Z(A,B,C,D,E,F)=A +AB +ABC+ABCD + ABCDE + ABCDEF.

3. Write the truth table of an OR gate and explain its behavior. Realise an OR gate using NAND gates only.

4. Draw the circuit using gates of an SR flip flop and obtain its truth table.

5. Draw the circuit of a radix-8 synchronous up counter and using timing diagrams explain its working.

6. Sketch the circuit of a half subtractor. Show how a full subtractor is built using half subtractors.

7. Draw the gate 4 1 it of a 1 to 4 de-multip and explain its working

8. State and explain the functions of the different logical components of an ALU.

(a) (345.625)10 into its binary equivalent (b) (FED)16 into its decimal equivalent.

2. Reduce the following Boolean expressions into its minimal form:

(a) W(K,L,M)=KL+LM+KM (b) Z(A,B,C,D,E,F)=A +AB +ABC+ABCD + ABCDE + ABCDEF.

3. Write the truth table of an OR gate and explain its behavior. Realise an OR gate using NAND gates only.

4. Draw the circuit using gates of an SR flip flop and obtain its truth table.

5. Draw the circuit of a radix-8 synchronous up counter and using timing diagrams explain its working.

6. Sketch the circuit of a half subtractor. Show how a full subtractor is built using half subtractors.

7. Draw the gate 4 1 it of a 1 to 4 de-multip and explain its working

8. State and explain the functions of the different logical components of an ALU.

**PART B - [3 x 20 = Marks 60]**

Answer any THREE questions.

All questions carry equal marks.

Answer any THREE questions.

All questions carry equal marks.

9. Describe in detail error detecting and error correcting codes. Bring out their advantages and disadvantages as

error detectors.

10. A combination circuit gives an output 1 if there are exactly two ones in the input. Using a Karnaugh map design

the circuit.

11. Design a counter to count the sequence 000, 001, 011, 111, 110, 100, 000....

12. Using a suitable multiplexer design a circuit to give X (A, B, C, D) = Y- 0, 2, 3, 5, 7, 8, 9, 12,15.

13. What is a status register? What are its uses? How is a status register designed?

9. Describe in detail error detecting and error correcting codes. Bring out their advantages and disadvantages as

error detectors.

10. A combination circuit gives an output 1 if there are exactly two ones in the input. Using a Karnaugh map design

the circuit.

11. Design a counter to count the sequence 000, 001, 011, 111, 110, 100, 000....

12. Using a suitable multiplexer design a circuit to give X (A, B, C, D) = Y- 0, 2, 3, 5, 7, 8, 9, 12,15.

13. What is a status register? What are its uses? How is a status register designed?