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# Centre for Development of Advanced Computing(C-DAC) 2004 M.C.A -103 Digital Electronics - Question Paper

Saturday, 02 February 2013 02:30Web

END-TERM exam
FIRST SEMESTER [MCA] - DECEMBER 2004
Paper Code: MCA-103 Subject: Digital Electronics
Time: three Hours Maximum Marks: 60

Q. 1. (a) decrease the following:-
(i) AB + A + AB
(ii) (AB + C) (AC + BC) + ABC + AB
(b) provide the block diagram of exclusive OR (XOR) gate using four NAND gates
only. Write its truth table also.
(c) Subtract (01001)2 from (01000)2 using
(i) 1’s Complement method.
(ii) 2’s Complement method.
(d) What is the range of signed and unsigned decimal values that can be represented by 8-bits?

Q. 2. (a) Perform the BCD addition of numbers 286 and 548.
(b) Design a Gray to Binary code converter using NAND gates only.
F (W, X, Y, Z) =  (0, 2, 5, 6, 8, 10)
(c) Convert the decimal number 3567 to
(ii) Octal Number

Q. 3. (a) Show how the subsequent expression can be implemented using NAND gates only.
X= (A+B) (C+D)
(b) For the subsequent circuit, determine the Boolean function for the output F.

Q. 4. (a) Minimize the 4 variable logic function.
f(A, B, C, D) = (A + B + C + D) (A + C + D).(A + B + C + D).
(B + C ) .(B + C).(A + B).(B + D)
(b) Implement the expression using 8:1 multiplexer
f (A, B, C, D) = m(0, 2, 3, 6, 8, 9, 11, 14)

Q. 5. (a) What do you understand by race around condition in a J-K flip flop? How is it removed in J-K master Slave flip-flop? discuss the working of masterslave flip-flop in detail by giving its block diagram and truth table.
(b) Design a J-K kind synchronous counter to count the subsequent states.
5, 8, 2, 7, 13, 0, 5, ………..

Q. 6. (a) discuss the working of an 8-bit serial-in-parallel-out shift register by giving its block diagram. How long will an eight bit binary number take in this register if the lock frequency is
(i) one Mhz
(ii) five Mhz.
(b) discuss the working of an OP-AMP based Schmitt Trigger Circuit.

Q. 7. (a) discuss the ladder method of a D/A converter. How does this method overcome the disadvantages of a weighted register method?
(b) Show how to expand 256 x four RAMs to find a memory expansion of 1024 x 4.

Q. 8. (a) provide and discuss the concept of a tri-state buffer circuit. Write its advantages also

(b) What is a microprocessor? provide the pin diagram of an 8085 µp and briefly discuss the pin architecture. provide your ans with reference to the system bus architecture and register organization of 8085 µp.

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 Earning:   Approval pending.
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