MPICH
MPICH is a free portable implementation of the MPI . MPI is a standard for data exchange with messages in distributed computer networks that are used for parallel computing. MPICH is Free Software and is available for most Unix and Linux platforms, Mac OS X and Microsoft Windows . MPICH is a program library.
The first implementation of MPICH is MPICH1 and implements the MPI standard in version 1.1. The current implementation is currently MPICH2 for MPI 2.0. Data exchange between different hardware platforms is not yet supported.