Parallel processing offers the potential to achieve faster program execution by having multiple processors work together. Traditionally, these processors were contained within a dedicated parallel supercomputer; now, it may be more cost-effective to use the processors of a group, or cluster, of PCs or workstations. The problem with clusters as parallel machines is that conventional networks were not designed to coordinate processors working on a single program, but to transfer large blocks of data between essentially independent systems.
Instead of using conventional network hardware and software, we suggest that it may be more appropriate to use a simple custom synchronization unit to coordinate the actions of a cluster of machines. In particular, we discuss how PAPERS, Purdue's Adapter for Parallel Execution and Rapid Synchronization, can make a cluster behave as a single tightly-coupled parallel supercomputer.