A complete implementation of MPI for the Fujitsu AP1000+ is presented. The library can employ a number of different mechanisms in implementing the send and receive message passing operations. The method of detecting the arrival of new messages can be realized through interrupt-driven and polling techniques. Transferring message data is achieved by either sending the message data directly to the receiver ``in-place'', or using a rendezvous method which allows the use of a fast noncopying nonblocking remote-fetching operation.The MPI library exhibits good performance compared to the native message passing library, and allows the user to decide at runtime which mechanisms will be used in order to achieve the best performance on a per-application basis.