Simple circuits that work for complicated reasons

Abstract

This paper brings together a selection of creative circuit designs and ideas that Charles Molnar devised while working at Sun Microsystems Laboratories. The circuits offer fast implementations of functions that were severe speed bottlenecks in our existing systems. Charlie strongly believed that reliable and very fast circuit module implementations must make use of local delay constraints, and that the interfaces between these modules can then employ more robust and delay-insensitive signaling protocols. These circuit designs provided us with: an unusual 2-phase arbiter known as the propeller arbiter; a method of using arbiters to measure on-chip delays very precisely; and three versions of a latch control circuit, known as a Charlie Box.