The CPU (Central Processing Unit) in the NES is called MOS 6502 and is an 8-bit CPU. The chip that contains the CPU also contains other electronics that generate sound for games and help with some other things. There are two different versions of the chip called 2A03 and 2A07 that are used in different regions of the world (2A03 works with NTSC TVs, 2A07 with PAL TVs). It was made by a company called Ricoh.