As part of the overall plan for the Super NES, rather than include an expensive CPU that would still become obsolete in a few years, the hardware designers made it easy to interface special coprocessor chips to the console (just like the MMC chips used for most NES games). This is most often characterized by 16 additional pins on the cartridge card edge. The Super FX is a
RISC CPU designed to perform functions that the main CPU could not feasibly do. The chip was primarily used to create 3D game worlds made with polygons, texture mapping and light source shading. The chip could also be used to enhance 2D games with effects such as sprite scaling and rotation. The Nintendo fixed-point
digital signal processor (DSP) chip allows for fast vector-based calculations, bitmap conversions, both 2D and 3D coordinate transformations, and other functions. Four revisions of the chip exist, each physically identical but with different
microcode. The DSP-1 version, including the later 1A and 1B bug fix revisions, is most popular; the DSP-2, DSP-3, and DSP-4 are in only one game each. Similar to the 5A22 CPU in the console, the SA-1 chip contains a 65c816 processor core clocked at 10 MHz, a memory mapper, DMA, decompression and bitplane conversion circuitry, several programmable timers, and CIC region lockout functionality. Many cartridges contain other enhancement chips, most of which were created for use by a single company in a few games; the only limitations are the speed of the Super NES itself to transfer data from the chip and the
current limit of the console. ==Design change==