COMP2421 Assignment 5

MA Mingyu (Derek) | 14110562D | Nov 12, 2017
derek.ma | derek.ma@connect.polyu.hk

Question 1

Characteristic table:

\(S\) \(R\) \(Q(t)\) \(Q(t+\Delta)\)
0 0 0 disallowed
0 0 1 disallowed
0 1 0 1
0 1 1 1
1 0 0 0
1 0 1 0
1 1 0 0
1 1 1 1

K-map:

row:\(SR\); col:\(Q(t)\) 00 01 11 10
0 X 1 0 0
1 X 1 1 0

Next-state equation:

\(Q(t+\Delta) = \overline{S(t)} + R(t)Q(t)\)

The relationship between this latch and the one using NOR gates is exact opposite.

\(S\) here is actually \(\overline{S}\), and \(R\) here is actually \(\overline{R}\) compared to the one using NOR gates.

Question 2

Question 3

Characteristic table for this latch:

\(E\) \(D\) \(Q\) \(Q_{next}\) \(\overline{Q_{next}}\)
0 X 0 0 1
0 X 1 1 0
1 0 X 0 1
1 1 X 1 0

where X means "don't care the value of this variable".

Another possible characteristic table is:

\(E\) \(D\) \(Q\) \(Q_{next}\) \(\overline{Q_{next}}\)
0 0 X \(Q\) \(\overline{Q}\)
0 1 X \(Q\) \(\overline{Q}\)
1 0 X 0 1
1 1 X 1 0

Question 4

Question 5