Present invention unity parallel processing systems and methods facilitate flexible utilization of sequential program applications in a distributed multi-computer parallel processing environment. The new unity parallel processing architecture enables multiple processing nodes (e.g., SMPs) to perform multi-thread processing within the multiple processing nodes while providing a shared virtual global memory space. Symmetric multiprocessors run shared memory applications with modified runtime guidance directives that permit the memories to emulate a virtual global memory across the plurality of symmetric multiprocessors. Within each SMP node, programs utilize multiple threads according to directives and library calls. Across multiple SMP nodes, each SMP node is treated as a single process with one-way communication to other SMP nodes. Portions of the program data are stored in memories associated with the SMP nodes and communication of the program data across multiple SMP nodes is controlled by unity compiler directives.