EE 2000 Logic Circuit Design,
Semester A, 2008/09
Tutorial 3 Solution
Week 4 (22
nd
, 24
th
, 25
th
September, 2008)
Level 1: Review Questions
Question 3:
Implement the function
f(A, B, C) = AC + BC’
by using NAND operators
only.
Answer:
)
(
)
(
)
,
,
(
C
B
AC
C
B
AC
C
B
AC
C
B
A
f
=
+
=
+
=
f
B
C
A
Question 9:
What is the logic which controls a staircase light associated with two
switches A and B located at bottom and top of staircase respectively?
Answer:
XNOR (or XOR, depends on the design)
Question 42:
If a three-variable switching function is expressed as the product of
maxterms by
f(A, B, C) =
Π
M(0, 3, 5, 6)
Answer:
c)
Σ
m
(1, 2, 4, 7)
Level 2: Problems
Question 13:
a) Simplify the logic function
f = AB + AC’ + C + AD + AB’C + ABC
b) Simplify Boolean function
F = A’C + A’B + AB’C + BC
Answer:
a) f = AB + AC’ + C + AD + AB’C + ABC
= (AB + ABC) + AC’ + C + AD + (AB’C + ABC) (idempotency)
= AB + AC’ + C + AD + AC (absorption, adjacency)

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