The IBM SP2 is Scalable POWERpallel2 system. POWER means Performance Optimized With Enhanced RISC. And, RISC is a Reduced Instruction Set Computer.
The SP2 consists of up to several hundred nodes which are all RISC 6000 superscalar processors. (Superscalar means that more than one instruction per clock cycle can be performed.) The SP2 can be considered a distributed memory machine because each node has its own local memory.
When programing in parallel on the SP2, you can run programs in SPMD (single program, multiple data) mode or MIMD (multiple instruction, multiple data) mode.