PURBANCHAL UNIVERSITY

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Lawrence Palmer
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1 [c] Implement a full adder circuit with a decoder and two OR gates. [4] III SEMESTER FINAL EXAMINATION-2006 Q. [4] [a] What is flip flop? Explain flip flop operating characteristics. [6] [b] Design and explain 4 bit up-down ripple counter. [10] Q. [5] [a] Design 4 bit parallel input and serial output shift register. [10] Attempt any FIVE questions Q. [1] [a] Convert (247.36) 10 into binary, octal and hexadecimal. [4] [b] State and prove De' Morgans Theorem. [4] [c] Prove that AB +A C + BC = AB + A C [4] [d] Obtain the minimal expression for Σm(1,2,4,6, 7) and implement it using universal gates. [4] Q. [2] [a] Design a alarm system which is connected to three switches and the alarm will ring when majority of switches are pressed it takes value 1 and 0 when switches is not present. [5] [b] Design 4 hit binary to gray code convener. [8] [c] Implement F = A(B +CD)+BC using only NOR gates. [3] Q. [3] [a] Design any one type of decimal adder. [8 [b] Construct a 4 16 decoder using 3 8 decoders.[8] [b] Design an adder/subtractor circuit with one selection variables and two inputs A and B, when s = 0, the circuit performs A+B and when S=l, the circuit performs A-B. Draw complete circuit. [6] Q. [6] [a] Which is the fastest logic family? Write short notes on TTL. [10] [b] Explain the working of shifter with heat diagram. [6] Downloaded from 1

2 [b] A combinational circuit is defined by the following three Boolean functions: [8] III SEMESTER FINAL EXAMINATION-2005 F1= (x+y) +xyz F2=(x+y) +x yz F3=xyz+(x+y) Design the circuit with a decoder and external OR gates. Q. [3] [a] Magnitude Comparator? Design a 2-bit Attempt any FIVE questions Q. [1] [a] What do you mean by digital system? What is the signification of binary number in digital system. Explain. [2+3] [b] Perform the following conversions: [2+2] [i] (F3A7C2) H to octal. [ii] ( ) 10 to binary. [c] Perform the following subtractions of unsigned numbers. [ ] [i] (567.8) 10 (2345) 10 using 9 s complement of subtrahend. [ii] (10110) 2 (1011) 2 using 2 s complement of subtrahend. Q. [2] [a) Simplify the following function using K-map: F = WX + WXZ + W Y Z + W XY + WXZ Implement the simplified function using NAND gates only. Downloaded from 2 Magnitude Comparator using all the necessary Boolean expressions for circuit implementation. [1+7] [b] Differentiate Multiplexer and Demultiplexer circuits. [5] [c] What is Programmable Logic Array (PLA)? Explain it. [3] Q. [4] [a] Explain the operations of a clocked RS flip-flop with the help of its characteristic table What is the drawback of this flip-flop? [6+1] [b] What do you mean by registers? Explain the operation of a 4-bit serial in serial out register with a timing diagram. [1+6] [c] Write brief note on ALU. [2] Q. [5] [a] Design a counter with the following repeated binary sequence 0,1,3,2. [b] Design an arithmetic circuit with one selection variable S and two n-bit data inputs A and B the circuit generates the following four arithmetic operations in conjunction with the input carry

3 C in. Draw the logic diagram for the first two stages. [9] S C in =0 C in =1 0 D= A+B=(ADD) D=A+1(INCREAMENT) 1 D=A-1(DECREMENT) D=A+B +1(SUBTRACT) Q. [6] [a] Explain the circuit operation of I 2 L circuit with necessary diagrams. [8] [b] Explain the circuit operation of DTL circuit with necessary circuit diagrams. [8] Downloaded from 3

4 Q. [4] [a] Differentiate between Encoder and Decoder. [b] Explain the working of T flip flop. [5] III SEMESTER BACK-PAPER EXAMINATION-2005 [c] Design a mode 10 synchronous counter. And explain its working using timing diagram. [8] Q. [5] [a] Explain the working mechanism of Ripple Counter. [5] [b] Explain the working of status Register. [5] [c] Design a logic circuit that can add and subtract Attempt any FIVE questions Q. [1] [a] What is analog and digital system? Explain [5] [b] Explain what is Bit, byte, nimble and radix. [5] [c] Convert (444.55) 10 into binary, octal and hexadecimal. [6] Q. [2] [a) Design a full substractor circuit using NAND gate or NOR gate only. [7] [b] State and prove de Morgan s theorem. [5] [c] Subtract (101) 2 from ( using 2 s complement method. [4] Q. [3] [a] What is multiplexer. Design 16 1 MUX using 4 1 MUX. [2+4] [b] Simplify the folio win function using k-map:[3+3] F =AB + ABCD + BC D+AC Implement the simplified function in a circuit. [c] Explain 2 bit Binary Parallel adder with one example. [4] Downloaded from 4 two 3-bit data with one selection variable S. If S=0, the circuit adds and if S=1, the circuit subtract. [6] Q. [6] [a] Which is the faster logic family? Write short note on CMOS logic family. [1+6] [b] Differentiate RTL and DTL circuits. [9]

5 [b] What is Full Adder? Briefly explain how parallel binary adder works. [3+3] III SEMESTER FINAL EXAMINATION-2004 [c] What is Decoder? Explain with help of 2X4 Decoder. [3] Q. [4] [a] What is flip flop? Write short note on SR Filpflop. [1+3] [b] Design a counter using T Flip-flop which will count in 0,2,3,1,0 sequence. [6] Attempt any FIVE questions Q. [1] [a] Covert (333.33)10 into binary, octal and hexadecimal. [5] [b] Prove A B C +A B C+A BC +ABC +ABC=A B +A C +AB [c] state and prove De-Morgan's theorem. [5] [d] Subtract (37) 10 -(35) 10 in l's compliment method.[3] Q. [2] [a] What is NAND gate? Prove that NAND gate is Universal gate. [3+5] [b] Design a bell system which is connected to three switches and the bell will ring when majority of switches are pressed. Assume when switch is pressed it takes value 1 and when switch is not pressed it takes value 0. [5] [c] Write short note on EX-OR gate. [3] Q. [3] [a] What is multiplexer? Design 8X1 Multiplexer using 4X1 multiplexer. [3+4] Downloaded from 5 [c] Draw an Asynchronous Up Counter using three JK master slave Filp-flop. Explain the operation using timing diagram. [6] Q. [5] [a] What is shift register? Explain the working of sereial in serial out shift register. [1+5] [b] Why memoir is necessary in a Sequential Circuit? Write short note on Memory Unit. [2+6] [c] Differentiate between Combination Sequential Circuits. [2] Q. [6] [a] What is Arithmetic and logic unit of a computer? How Arithmetic and logic unit works? Explain. [1+6] [b] Explain the working of shifter with neat diagram. [5] [c] Which is the fastest Logic family? Write short note on CMOS bogie Family. [1+3]

6 [c] Design a BCD adder circuit capable of adding BCD equivalent of 2 digit decimal number with III SEMESTER BACK-PAPER EXAMINATION-2004 short explanation. [6] Other portion are remaining. Attempt any FIVE questions. Q. [1] [a] Convert: [4 1.5] [i] (222) 10 ( ) 16 [ii] (0.625) 10 ( ) 2 [iii] ( ) 2 ( ) 8 [iv] (F2) 16 ( ) 2 [b] What is binary number system? How are binary numbers converted to other number systems?[1+3] [c] What is canonical form of Boolean function? Explain its significance. Convert (A+B) (B+C) into canonical form. [2+2+2] Q. [2] [a] simplify the Boolean function using K-map: [4] F= A B C +B CD +A BCD +AB C [b] Draw 4-bit binary Adder/Subtractor circuit. Explain how binary addition/subtraction is carried. [6] Downloaded from 6

7 D A = X.Y +X Y and D B = A.X+B.Y III SEMESTER FINAL EXAMINATION-2002 The figure in the margin indicates full marks. GROUP-A [8 6 = 48] Attempt any EIGHT questions Q. [1] Discuss on various types of numbering system with examples of each and their conversion processes. Q. [2] Why the method of 2 s complemental subtraction is used? Subtract binary 1010 form 1101 using 2 s complement subtraction. Q. [3] Draw the truth table for a full adder and also draw the circuit for a carry part of addition based on the truth table. Q. [4] Write a short note on programmable Logic Array (PAL) with suitable example. Q. [5] Why ripple counters are so called? Explain the operation of a 3-bit ripple counter with a neat diagram. Q. [6] What are the relations between combinational circuit and sequential circuit? Also describe sequential circuit with a block diagram. Q. [7] A Sequential circuit is to be constructed using two D flip flops A and B. If the input equations of the flip-flops are Downloaded from 7 Where X and Y are the input variable and A and B are the normal output of flip-flops A and B and if z=(a+b).(x.y).draw a sequential circuit based on the given equations. Q. [8] Draw a diagram of 6-bit serial in parallel out shift register and also draw the required waveforms of input and output sides. Q. [9] Show a 4 16 decoder can be made with two 3 8 decoders. Q. [10] What are code converters? Write down a neat diagram for BCD to excess 3 converters? GROUP-B Attempt any FOUR questions. [4 8=32] Q. [11] Draw a neat diagram of a 4-bit magnitude comparator showing clearly whether the first number is greater then or equal to or less than the second number. Q. [12] What are universal gales? Prove their universality. Q. [13] Draw a 3-bit up-down counter and explain its operation and write it s count sequences with help of waveforms.

8 Q. [14] Draw a neat diagram of an ELC basic gate. The number of inputs should be 4(A, B, C) and two outputs for OR and NOR equivalent. Q. [15] There are three sensors on the lop of a building. One for measuring temperature, one for measuring humidity and the next is for measuring wind velocity. If a person has only one monitor and if that could display only one of the measured/sensed value at a time. Design a circuit and explain so as the person could monitor the sensed value in his monitor as per his wish. Downloaded from 8

Bachelor Level/ First Year/ Second Semester/ Science Full Marks: 60 Computer Science and Information Technology (CSc. 151) Pass Marks: 24

Bachelor Level/ First Year/ Second Semester/ Science Full Marks: 60 Computer Science and Information Technology (CSc. 151) Pass Marks: 24 2065 Computer Science and Information Technology (CSc. 151) Pass Marks: 24 Time: 3 hours. Candidates are required to give their answers in their own words as for as practicable. Attempt any TWO questions: