Dec 2014
Bachelor of Computer Applications (BCA) Examination
III Semester
Digital Computer Electronics
Time 3 Flours] [Max. Marks 50
Note : Attempt all the five questions. Ail questions
carry equal marks.
1. (a) Perform the following subtraction, using 2's
complement subtraction method :
(i) M  N (ii) N  M where M = 10101100 and N =
11010101.
(b) Convert the binary number 1101 010 into following
codes :
(i) Gray Code (ii) Excess 3 Code (iii) BCD.
(c) Convert the following number to their indicated
bases :
(i) (58.3)10 = (?)8 (ii) (AF3) 6 = = (?)1
(iii) (627)8 = (?)lo (iv) (82.9)10 (?j2.
2. (a) Explain principle of duality with suitable
example.
(b) (i) Simplify the following function using Boolean
algebra :
f = AD + ABCD' + A'B'C'D'  ABC' + A'B'CD + ABC.
(ii) Implement AND and OR gate using NAND gate.
(c) Implement full adder using half adders and external
gates.
3. (a) Obtain the minimal sum of products for the
function (use K map) :
F (A, B, C, D) = E (1, 3, 7, 11, 15)
d (A, B, C,'D) = E (0, 2, 5) d : don't care.
(b) Explain the following in brief :
(i) Standard Sum of Product
(ii) Standard Product of Sum
(iii) Canonical Sum of Product
(iv) Canonical Product of Sum.
(c) Draw the truth table for a three input function
given below : f= (A, B, C) = AB + BC + AC.
4. (a) Implement the full add.er with the help of
decodes and external gate.
(b) Compare the different type of TTL on the basis of
following parameter :
(i) Fanin . (ii) Fanout (iii) Power dissipation.
(c) Explain 8 x 1 multiplexer.
5. (a) What are the problems in the level triggering ?
Flow it these problems can be removed?
(b) Explain the difference between buffer register and
shift register using suitable example.
(c) Design a module10 ripple counter.
