ISC Board Guess paper

Computer Science

[Set –I]

Part -I

Answer all questions in this part

While answering questions in this part,indicate briefly

Your working and reasoning wherever required.

Q 1. (a) Using Boolean algebra show that the dual of exclusive OR is equivalent to the compliment of exclusive OR.

(b) Show that A+A'.B=A+B

(c) Define maxterm and minterm of the Boolean expression.What is the relation between them(show it by example).

(d) What types of multivibrators are used for clock generators in digital computer systems? Why are clocks needed in a digital computer system?

(e) Reduce the following to its simplest form using laws of Boolean Algebra At each step state clearly the law used for simplification.

C.D'+A+A+C'.D'+A.B

 

Q 2. (a) Convert the following infix expression to its postfix form:

A + ((B+C)-(D+E)*F)/G

(b) Why is the NOR gate regarded as Universal Gate? Draw the logic gate symbol and make the truth table for the two input NOR gate.

(c) Find the complement of X. (Y.Z’ + Y’. X) using De Morgan’s law. Show the relevant reasoning. Do not reduce the function.

(d) What is the principle of duality? Give one example.

(e) Obtain the logic circuit of the following boolean expression using NOR gates only

F(X,Y,Z) = (X + Y).(Y + Z).(Z + X)

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