Programmable array logic: achieves very low delay in return for simple, nearly fixed, wiring structure.
All expressions are in SOP form with limited number of products.
A typical PAL with 7 inputs and 7 I/Os.
Contents of the PAL macrocell.
pin 16 = o1; pin 2 = a; pin 3 = b; pin 4 = c o1.oe = ~a; o1 = (b & o1) | c; -x-- ---- ---- ---- ---- ---- ---- (oe term) --x- x--- ---- ---- ---- ---- ---- (pin 3 and 16) ---- ---- x--- ---- ---- ---- ---- (pin 4) xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx x (macrocell fuse)
Example programming of a PAL showing only fuses for the top macrocell.