MONITORS, MESSAGES, AND CLUSTERS - THE P4 PARALLEL PROGRAMMING SYSTEM

p4 is a portable library of C and Fortran subroutines for programming parallel computers. It is the current version of a system that has bee n in use since 1984. It includes features for explicit parallel progra mming of shared-memory machines, distributed-memory machines (includin g heterogeneous networks of workstations), and clusters, by which we m ean shared-memory multiprocessors communicating via message passing. W e discuss here the design goals, history, and system architecture of p 4 and describe briefly a diverse collection of applications that have demonstrated the utility of p4.