Guru Jambheshwar University 2006 M.C.A Digital electronics - Question Paper
M.C.A. (Second Year) EXAMINATION % ,
(5 Years Integrated Course)
(Re-appear)
MCA-203 DIGITAL ELECTRONICS
Time : 3 Hours Maximum Marks : 100
Note : Attempt any Five questions. All questions carry equal marks.
1. (a) State and prove De-Morgans Theorems. 6
(b) Explain NAND and NOR logic operations. 5
(c) Obtain AND, OR and NOT operations using NOR operations. 9
2. Do as directed : 20 (i) (10010101)2 = (?)10
(ii) (10-625), 0 = (?)2
(iii) (6A28)16 = (?)8
(iv) (32 7*89) 10 = (?)BCD CODE
(v) (1101*0110111)2 - (?)8
(vi) (15)10 - (8)I0 = (?)
(Using one's complement)
(vii) Find 2's complement of 01101
(viii) (1100010)2 - (111 )2 = (?)2
(ix) (1101101)2 x (101)2 = (?)2
(x) (-- 48) 10 - (23) using 2's complement
3. Simplify the following using K-maps : 20
(a) /(A, B, C, D) = *M (4, 5, 6, 7, 8, 12)
d( 1, 2, 3, 9, 11, 14)
(b) /(A, B, C, D) - Im (0, 3, 5, 6, 9, 10,
12, 15)
Also realize them using minimum number of gates.
A BCD message appears in four input lines of a switching circuit. Design an AND, OR, NOT gate network which produces an output *1' whenever input combination is 0, 2. 3, 5 or 8. Construct a 5 to 32 line decoder with four 3 to 8 line decoders with enable and one 2 to 4 line decoder. 10
Explain the operation of master-slave J-K flip-flop with complete circuit arrangement and truth table. How the race around condition of J-K flip-flop is removed ? 15
4. (a)
(b)
5. (a)
(b)
6. (a)
(b)
Show that J-K flip-flop can also be used as T and D flip-flops. 5
Draw' the diagram for universal shift register and explain its operation. 15 Write a short note on Parity Generator/ Checker. 5
3 P.T.O.
7. (a) Draw the diagram for 3 bit ripple counter
and explain its operation with the help of waveforms. Use T flip-flop. 10
(b) Design a four bit decade counter (synchronous). Use J-K flip-flops. 10
8. (a) Explain various characteristics of digital
IC's. .10
(b) Draw the circuit diagram for TTL Totem Pole NAND gate and explain its working. 10
J-4272 4 1,500
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