(i) A family intends to purchase a smart phone depending on the criteria given
below:
• Quad core processor with internal memory of 64 GB or more but not a
resale phone
OR
• Resale phone with quad core processor but without warranty
OR
• Processor is not a quad core but with a warranty of 1 year and the internal
memory is of 64 GB or more
The inputs are:
P - Quad core processor
M - Internal memory of 64 GB or more
R - Resale phone
W - Warranty of 1 year
(In all the above cases, 1 indicates yes and 0 indicates no.)
Output: X [1 indicates purchased, 0 indicates not purchased for all cases]
Draw the truth table for the inputs and outputs given above and write the SOP
expression
(ii) What is a half adder? Draw the logic circuit for the SUM and CARRY expression
of a half adder using only NAND gates.
(iii) Simplify the following expression using Boolean laws:
F = PQ + ( P + Q ) • ( P + PR ) + Q
Solution
(i)
(ii) Half adder is a combinational logic circuit with two inputs and two outputs. The half adder circuit is designed to add two single bit binary number A and B. It is the basic building block for the addition of two single-bit numbers. This circuit has two outputs carry and sum.
