Abstract : This technical report describes a project undertaken by the graduate students in CS 568, Winter 1989, to design and implement a programmable hardware monitor. The goal of this project was to create a general purpose, highly programmable yet compact design for a hardware monitor to be implemented with custom Complementary Metal Oxide Semiconductor Very Large Scale Integration chips. The architecture is designed for easy extensibility and allows the monitor to be customized for use in a wide variety of computer systems, and to accommodate a broad range of applications. Although the project did not reach fabrication, a great deal of the layout was completed and simulated. The purpose of a hardware monitor is to detect and record hardware events in a computer system for the purposes of performance evaluation. A simple, and much used, approach to performance analysis is trace-driven simulation. Trace-driven simulation depends upon the collection of a trace of all addresses generated during the execution of one or more computer programs. The major problem of this approach is that a large amount of memory is required to store all the trace information. Additionally, methods for collecting address traces are often expensive and intrusive; the process of collecting the trace data may alter the behavior of the computer system while it is being traced. Keywords: Layout.