Program Level:

It is the next level consisting of independent programs for parallelism. Coarse Granularity  size is used at this level containing ten thousands of instructions. Time sharing is get at this level of parallelism. Parallelism at this level has been exploited through the operating system.

                             The relation between parallelism and grain sizes levels has been given in Table 1.

Coarse grain parallelism is traditionally executed in tightly shared memory or coupled multiprocessors like the Cray Y-MP. Loosely coupled systems are used to implemented medium grain program segments. Fine grain parallelism has been considered  in SIMD organization of computers.