This poster describes a course on the history of computing, designed for both a computer science program and for general undergraduate education.

Data-dependent completion time is a well-known advantage of self-timed circuits, one that allows them to operate at average rather than worst-case execution rates. A technique called early evaluation (EE) that extends this advantage by allowing self-timed modules to produce results before all of their inputs have arrived is described here. The technique can be applied to any combinational function and is integrated into the phased logic (PL) design methodology that accepts synchronous design entry and produces delay-insensitive self-timed circuits. We describe an algorithm that ensures that the resulting delay-insensitive circuits are safe, and develop a generalized method for inserting EE gates into any PL netlist. We give performance results for several benchmark circuits, including a five-stage pipelined CPU and a microprogrammed floating-point unit. Comparisons are made among clocked circuits, PL circuits, and PL circuits with EE. Simulation results show a clear performance benefit for PL circuits that use EE.

Locally Clocked Modules (LCMs) allow asynchronous communication between synchronous computational elements. The concurrency workbench models concurrent systems in the CCS process algebra. We describe the use of the concurrency workbench to specify, simulate, and verify implementations of LCMs and discuss its application to the specification of asynchronous circuits.

The author shows how a class of concurrent programming problems can be specified with formal grammars. These grammars, more powerful than path expressions, translate readily into Ada server tasks using the rendezvous and select-statement, though they may also be applied to other synchronization constructs. The grammars may be used to clarify informal specifications, to compare different specifications, and to analyze the behavior of implementations of such specifications. They may also be easily converted into Prolog programs that can be executed to generate the strings of events accepted by a grammar or by the Ada task being modeled. The automated translation from Ada to such grammars, and from grammatical specifications to Ada is discussed. The former facilitates the analysis of Ada programs; the latter yields Ada code of high quality.>