This series of fixed-point digital signal processor chips provides fast vector-based calculations, bitmap conversions, 2D and 3D coordinate transformations, and other functions.[7] The chip has four revisions, each physically identical but with different microcode. The DSP-1 version, including the later 1A die shrink and 1B bug fix revisions, was most often used; the DSP-2, DSP-3, and DSP-4 were used in only one game each.[8] All of them are based on the NEC μPD77C25 CPU and clocked at 7.6 MHz.[4][9]