Circlets: circuits as applets

Custom computing is concerned with deriving benefits from importing the flexibility of (software) programs into (conventionally, hardware) circuitry. A main aim is to gain speed-ups by programming at a level closer to the physical hardware, and in a medium that allows explicit parallelism. The paper is concerned with making the first steps towards another benefit: portability of circuitry in a network computing environment. That is, expressing applets in circuitry terms, rather than program terms. An implemented client server system is described, and then this is followed by discussion of how circlets-a term introduced in the paper to denote applets expressed as circuits-might best be represented in a portable form, and also how circlets may be supported by appropriate execution environments. At this point in history, it is apt to study the problems posed by circlets, since this should influence future directions for FPGA technological development.