Each processing node of the CM-5 has four vector units each of which is a 64-bit processor capable of performing 64-bit floating point arithmetic at the rate of 32 megaflops. The vector units function as memory controllers in addition to performing vector and scalar computations. All four vector units of a node processor can be used concurrently to perform arithmetic and/or memory access operations.
Therefore, using the vector units whenever possible is a good way to make your program execute significantly faster. In particular, numerical computations can benefit from using the capabilities of the vector units. The compilers for both CM Fortran and C* programs take advantage of the vector units by default.