Digital Electronics: Principles, Devices and Applications

316 Digital ElectronicsABCiSCoFigure 9.15Solution to problem 9.2 using a PLA.Output 3 (less than)= A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 (9.7)Output 4 (greater than)= A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 (9.8)Figures 9.16(a) to (d) show the Karnaugh maps for the four outputs. The minimized Booleanexpressions can be written from the Karnaugh maps as follows:Output 1equal to = A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 + A 1 A 0 B 1 B 0 (9.9)Output 2not equal to = A 1 B 1 + A 1 B 1 + A 0 B 0 + A 0 B 0 (9.10)