PAL (Chip)

A Programmable Array Logic (PAL) is a programmable logic device semiconductors used to implement any logic function in only one digital circuit. The function is stateless, which means that no intermediate state is saved.

PAL devices consisted of a small PROM (programmable read-only memory) core and additional output logic used to implement particular desired logic functions with few components.

You can use PALs in order to implement any logic function you might need by using a Karnaugh map.

First the PAL takes the Red Blue and Green inputs and uses it to point at a certain square in the map. Whatever the value inside that square is, will be the output of the PAL. The first square is only pointed to if no buttons are pressed at all.