Ricoh 2A03

The Ricoh 2A03, RP2A03 (NTSC), Ricoh 2A07, RP2A07 (PAL) or 2A03 is the 8-bit microprocessor in the NES console, (known as the Famicom in Japan), containing both CPU and APU.

Technical details
Produced Ricoh based on a MOS Technology 6502, NTSC versions of the NES use the 2A03, which is run at 1.79 MHz. PAL versions used the 2A07 processor, which is identical to the 2A03 except that it runs at 1.66 MHz. Timing differences between NTSC & PAL versions are to ensure that the sound output is the same on either. All audio waveform generation is done in the APU.