A novel VLSI architecture, PA**3 (programmable array of array adders), is described. This concept is an attempt to realize an efficient and effective universal mask/field programmable VLSI macrocell structure for special-purpose, as well as general-purpose, system implementations. Discuss the programming techniques for realizing functional PA**3 arrays. Programming is achieved by direct mapping of Boolean expressions that describe the functional systems to be implemented using these expandable arrays. This mapping can be performed either manually (resulting in better chip area usage) or through a PA**3 compiler.