TOP: an algorithm for three-level optimization of PLDs

Summary form only given. Presents an heuristic algorithm TOP (Three-level Optimization of PLDs), targeting a three-level logic expression of type g/sub 1/ o g/sub 2/, where g/sub 1/ and g/sub 2/ are sum-of-products and "o" is a binary operation. Such an expression can be implemented by a three-level Programmable Logic Device (PLD) consisting of PLA 1 and PLA2, implementing the first two levels of logic, and a set of two-input logic expanders, implementing the third level. Each logic expander can be programmed to realize any function of two variables. PLDs of this type seem to give a good trade-off between the speed of a flat PLA and density of a multi-level network of PLAs. TOP chooses the functionality of the logic expanders so that the area of the PLAs is minimized.