Programmable Array Logic and CPLDs (Complex Programmable Logic Devices) achieve very low delay in return for simple, nearly fixed, wiring structure.
All expressions are expanded to SOP form with limited number of products. .xi Expanding to sum-of-products form can cause near-exponential area growth (e.g. ripple carry converted to fast carry).
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)
15: (C) 2008-16, DJ Greaves, University of Cambridge, Computer Laboratory. |