
222 CHAPTER 5 / FUNCTION MINIMIZATION
5.10 MULTIPLE OUTPUT FUNCTIONS WITH DON’T CARES
The problem of selecting an optimum bond set is further complicated by the presence of
don’t cares in multiple output systems. Application of the CRMT minimization procedure
given earlier to such systems is illustrated by minimizing the following two four-variable
functions containing don’t cares:
F(A, B, C, D) =
m(3, 6, 8, 9, 12, 15) + φ(1, 4, 5, 11)
and
H(A, B, C, D) =
m(1, 4, 7, 10, 12, 13) + φ(2, 5, 6, 8, 11, 15).
(5.53)
The conventional fourth-order K-maps for functions F and H are shown in Fig. 5.8a.
The don’t cares are so chosen as to best meet the requirements ...