# 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.**

**(**decrease the following:-

**a)****(**AB + A + AB

**i)****(**(AB +

**i****i)****C)**(AC + B

**C)**+ ABC + AB

**(**provide the block diagram of exclusive OR (XOR) gate using four NAND gates

**b)**only. Write its truth table also.

**(**Subtract (01001)2 from (01000)2 using

**c)****(**1’s Complement method.

**i)****(**2’s Complement method.

**i****i)****(**What is the range of signed and unsigned decimal values that can be represented by 8-bits?

**d)****Q.**

**2.**

**(**Perform the BCD addition of numbers 286 and 548.

**a)****(**Design a Gray to Binary code converter using NAND gates only.

**b)**F (W, X, Y, Z) = (0, 2, 5, 6, 8, 10)

**(**Convert the decimal number 3567 to

**c)****(**Hexadecimal Number

**i)****(**Octal Number

**i****i)****Q.**

**3.**

**(**Show how the subsequent expression can be implemented using NAND gates only.

**a)**X= (A+

**B)**(C+D)

**(**For the subsequent circuit, determine the Boolean function for the output F.

**b)****Q.**

**4.**

**(**Minimize the 4 variable logic function.

**a)**f(A, B, C,

**D)**= (A + B + C +

**D)**(A + C + D).(A + B + C + D).

(B + C ) .(B + C).(A + B).(B + D)

**(**Implement the expression using 8:1 multiplexer

**b)**f (A, B, C,

**D)**= m(0, 2, 3, 6, 8, 9, 11, 14)

**Q.**

**5.**

**(**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.

**a)****(**Design a J-K kind synchronous counter to count the subsequent states.

**b)**5, 8, 2, 7, 13, 0, 5, ………..

**Q.**

**6.**

**(**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

**a)****(**one Mhz

**i)****(**five Mhz.

**i****i)****(**discuss the working of an OP-AMP based Schmitt Trigger Circuit.

**b)****Q.**

**7.**

**(**discuss the ladder method of a D/A converter. How does this method overcome the disadvantages of a weighted register method?

**a)****(**Show how to expand 256 x four RAMs to find a memory expansion of 1024 x 4.

**b)****Q.**

**8.**

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

**a)****(**What is a microprocessor? provide the pin diagram of an 8085 µp and briefly discuss the pin architectur

**b)****e.**provide your ans with reference to the system bus architecture and register organization of 8085 µp.

Earning: Approval pending. |