August 2000
LD201 : LOGIC DESIGN

QUESTION 5

Total Marks: 15 Marks

• Question 1
• Question 2
• Question 3
• Question 4
• Cover Page

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SUGGESTED SOLUTIONS
for Question 5

(Sequential Circuits) (15)
(a) Explain the difference between positive-edge triggering and positive-level
triggering of flip-flops. [2]

(b) Using three D flip-flops design the arithmetic shift right. [3]

(c) (i) Convert the JK flip-flop to a T flip-flop. [2]
(ii) Combine three T flip-flops together to form a three-bit synchronous
down counter. [4]

(d) The circuit below is supposed to be a 4 × 3-memory cell connected to a
decoder. Each binary cell BC behaves as described in Question 1(j). Complete
the circuit by connecting in a twelfth binary cell. You need not redraw the
whole diagram; show only the parts you have added. [4]