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V i d y a l a n k a rS.E. Sem. III [CMPN]
Digital Logic Design and ApplicationTime : 3 Hrs.] Prelim
Question Paper [Marks : 100
N.B. : (1) Question no. 1 is compulsory.(2) Answer any four out
of remaining six questions.
(3) Figures to the right indicate full marks.
1. (a) Convert the following numbers to the given base:(i)
(357.46)8 = (?)H
(ii) (656.25)8 = (?)6(iii)(123)4 = (?)2(iv) (11011.101)2 =
(?)10
[6]
(b) Implement the following Boolean function using 4: 1 MUX.
f (A, B, C, D) = m (0, 1, 2, 4, 6, 9, 12, 14)
[4]
(c) Prove: (i) AB AB (A B) (AB)
(ii) A(B C) AB BC A(B C) B(AC 1) C
[4]
(d) Design full adder using half adders. [4]
2. (a) (i) A panel light in the control room at the launching of
a satellite is to go ON if an only i
the pressure in both fuel and oxidiser tanks is equal to or
above a required minimum
and there are 10 minutes or less to lift off or if the pressure
in the oxidiser tank is equal
to or above a required minimum and pressure in fuel tank is
below a requiredminimum but there are more than 10 minutes to lift
off or if the pressure in the oxidisertank is below a required
minimum but there are more than 10 minutes to lift off.
Design a two level combinational circuit to control panel
light.(ii) Explain the following terms :
(1) Prime Implicant (2) Input variable
(3) Min. term (4) Max term
[6]
[4]
(b) Simplify the function using Quine McClusky method,f (A, B,
C, D) = m (4, 5, 8, 9, 11, 12, 13, 15).
Draw the logical diagram using NAND gates.
[10]
3. (a) Given the logic expression: A BC ABD ABCD .
(i) Express it in standard SOP form.
(ii) Draw K-map and simplify.(iii) Draw logic diagram using NOR
gates only.(iv) Draw logic diagram using NAND gates only.
(v) Express it in standard POS form.
[10]
(b) Design a clocked sequential R.S. Flip-flop. What is race
around condition? Is it in R.S.
Flip-flop? How is it avoided in J-K Flip-Flop?[8]
(c) Draw truth table, function table and excitation table of J-K
Flip-flop. [2]
4. (a) Explain the working of a Parallel In Serial Out Registers
using D-flip-flops. [6](b) Differentiate between :
(i) Synchronous and Asynchronous counters.
(ii) Combinational and Logic Circuits.
[4]
[4]
(c) Explain the lockout condition in counters with examples and
how it can be avoided. [4](d) Simplify using K-map:
f(A, B, C) = m (0, 2, 5, 7)
[2]
