Placement of Irregular Circuit Elements on Non-Uniform Gate Arrays

A program is described which was designed primarily to automatically place 5000 gate circuits comprising irregular drop-in components onto the UK5000 type gate array. The architecture of this array is unique, having latch cells together with basic logic cells already predefined on the uncommitted die and so is not a uniform structure. The program uses levels of automatic partitioning and placement forming initial solutions constructively followed by iterative improvement techniques. The concept of function dependent targeting for partitions is introduced together with a novel constructive initial partitioning algorithm. The concept extends throughout most of the subsequent improvement and placement processes. A novel placement improvement algorithm which considers the distribution of unused cells following initial placement is also introduced. The program is entirely file-driven, and uses plug-in algorithms making it suitable for a wide range of placement problems.