p4 [7,5] is a library of macros and subroutines
elaborated at Argonne National Laboratory for implementing parallel
computing on diverse parallel machines.
The predecessor of p4 (Portable Programs for Parallel
Processors) was the m4-based ``Argonne macros'' system, from which
it took its name. The p4 system is suitable to both shared-memory
computers using monitors and distributed-memory parallel computers
using message-passing. For the shared-memory machines, p4 supports a
collection of primitives as well as a collection of monitors. For the
distributed-memory machines, p4 supports send, receive, and process
p4 is still used in MPICH  for its network
implementation. This version of p4 uses Unix sockets in order to
execute the actual communication. This strategy allows it to run on a
PARMACS  is tightly associated with the p4
system. PARMACS is a collection of macro extensions to
the p4 system. In the first place, it was developed to make Fortran
interfaces to p4. It evolved into an enhanced package which
supported various high level global operations.
The macros of PARMACS were generally used in order to configure
a set of p4 processes. For example, the macro
torus created a
configuration file, used by p4, to generate a 3-dimensional
graph of a torus. PARMACS influenced the topology features of MPI.
PVM (Parallel Virtual Machine)  was produced as a
byproduct of an ongoing heterogeneous network computing research
project at Oak Ridge National Laboratory in the summer of 1989. The
goal of PVM was to probe heterogeneous network computing--one of the
first integrated collections of software tools and libraries to enable
machines with varied architecture and different floating-point
representation to be viewed as a single parallel virtual machine. Using
PVM, one could make a set of heterogeneous computers work together for
concurrent and parallel computations.
PVM supports various levels of heterogeneity. At the application
level, tasks can be executed on best-suited architecture for their
result. At the machine level, machines with different data formats are
supported. Also, varied serial, vector, and parallel architectures are
supported. At the network level, a Parallel Virtual Machine consists
of various network types. Thus, PVM enables different serial, parallel,
and vector machines to be viewed as one large distributed memory
There was a distinct parallel processing system, called Express . The main idea of Express was to start with a sequential version of a program and to follow Express recommended procedures for making an optimized parallel version. The core of Express is a collection of communication, I/O, and parallel graphic libraries. The characteristics of communication primitives were very similar with those of other systems we have seen. It included various global operations and data distribution primitives as well.