Compaq MPI Version 1.9 requires Tru64 UNIX Version 4.0a or higher. The Fortran runtime libraries are also required.
In addition, if you need MEMORY CHANNEL[TM] support, all cluster members require Compaq TruCluster software (or TruCluster MEMORY CHANNEL[TM] software), version 1.5 (requires Tru64 UNIX V4.0d or higher) or higher. You can also use version 1.4 of the TruCluster or MEMORY CHANNEL software if a patch is installed (see Section 2.5.2).