The above works fine on most Unix platforms, including the Cray Y-MP, Linux PC's, SGI's, etc. Tucked in the pages of a Cray Research Service Bulletin is the real scoop. Cray states that the increased address space on the T90 and MPP systems requires a two-word Fortran Character Descriptor in some of the Fortran system interface routines. Cray has provided alternative interface routines that conform to the Posix Fortran 77 Language Interfaces standard. On systems where this doesn't happen automatically, you'll need to run it through the C preprocessor first, with appropriate flags.
Full details are available in the man pages.
The master communicates with the slave on PE0, and no other. The slave on PE0, in turn, is designated as special, and relays data and instructions to all of the other slaves. In a sense, this amounts to having two masters, one on the Y-MP and a second on PE0. Another simpler approach is to treat the Y-MP process as the sole master, and open a pvm circuit from it to each and every slave. Once a program following this method is working, the programmer could move some, or even all, of the master's duties to the slave on PE0.