Multiple personality integrated circuits and the cost of programmability

This dissertation explores the cost of programmability in computing devices as measured relative to fixed-function devices implementing the same functionality using the same physical fabrication technology. The central claim elevates programmability to an explicit design parameter that (1) can be rigorously defined, (2) has measurable costs amenable to high-level modeling, (3) yields a design-space with distinct regions and properties, and (4) can be usefully manipulated using computer-aided design tools. The first portion of the the work is devoted to laying a rigorous logical foundation to support both this and future work on the subject. The second portion supports the thesis within this established logical foundation, using a specific engineering problem as a narrative vehicle. The engineering problem explored is that of mechanically adding a useful degree of programmability into preexisting fixed-function logic while minimizing the added overhead. Varying criteria for usefulness are proposed and the relative costs estimated both analytically and through case-study using standard-cell logic synthesis. In the case study, a methodology for the automatic generation of reconfigurable logic highly optimized for a specific set of computing applications is demonstrated. The approach stands in contrast to traditional reconfigurable computing techniques which focus on providing general purpose functionality at the expense of substantial overheads relative to fixed-purpose implementations.