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Digital Circuits and Logic Design
Notes Medium priority: Next state of the same state should be given adjacent assignments in the state
map.
Lowest priority: States with the same output for a given input should be given adjacent
assignments in the state map.
Figure 10.15: Highest Priority
Figure 10.16: Medium Priority
Figure 10 17: Lowest Priority
The guidelines, illustrated in the Figure 10.15, 10.16, and 10.17 above for the candidate states a
and b, are ranked from highest to lowest priority. The first two rules attempt to group together
ones in the next-state maps, while the third rule performs a similar grouping function for the
output maps. The state assignments are done by listing all the state adjacencies implied by the
guidelines, satisfying as many of these as possible.
Table10.16: The State Transition Table for a (non-minimal) Mealy Machine
Next state Output
Input sequence Present state
X = 0 X = 1 X = 0 X = 1
Reset S0 S1′ S1′ 0 0
0 or 1 S1′ S3′ S4′ 0 0
00 or 10 S3′ S0 S0 0 0
01 or 11 S4′ S0 S0 1 0
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