 Using late-model compilers, the machine attained a standard mathematical operations rate of 500 kilo-FLOPS, but the handcrafted computer assembler managed to deliver approximately 1 mega-FLOPS.A simpler, albeit much slower and less expensive version, implemented using a more traditional serial processor design rather than the 6600's parallel functional units, was released as the CDC 6400, and a two-processor version of the 6400 is called the CDC 6500.A FORTRAN compiler, known as MNF (Minnesota FORTRAN), was developed by Lawrence A. Liddiard and E. James Mundstock at the University of Minnesota for the 6600.