Ricoh 2A03

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Ricoh 2A03 / Ricoh 2A07
General Info
Common manufacturer(s)
Max. CPU clock rate1.79 MHz
Architecture and classification
Min. feature size6 μm
Instruction setMOS 6502
Physical specifications
  • 1
  • Through-hole Dual Inline Package (DIP)

The Ricoh 2A03 or RP2A03 (NTSC version) / Ricoh 2A07 or RP2A07 (PAL version) is an 8-bit microprocessor manufactured by Ricoh for the Nintendo Entertainment System video game console. It was also used as a sound chip and secondary CPU by Nintendo's arcade games Punch-Out!! and Donkey Kong 3.

Technical details[edit]

The Ricoh 2A03 contained a second sourced MOS Technology 6502 core, modified to disable the 6502's binary-coded decimal mode (possibly to avoid a MOS Technology patent). It also integrated a programmable sound generator (also known as APU, featuring twenty two memory-mapped I/O registers),[1] rudimentary DMA, and game controller polling.[2]

Regional variations[edit]

PAL versions of the NES (sold in Europe, Asia, and Australia) used the Ricoh 2A07 or RP2A07 processor, which was identical to the 2A03 except for a different clock divider and the 50 Hz vertical refresh rate used in the PAL television standard, with the exception of the 16 hard-coded sampling rates for the Delta modulation-encoded sample playback unit. The changes were made in order for sampled sounds to maintain the original pitch of the RP2A03 with the new clock divider.

See also[edit]


  1. ^ "Sound generators of the 1980s home computers". Retrieved 2019-12-02.
  2. ^ Taylor, Brad (April 23, 2004). "2A03 technical reference". Archived from the original on October 17, 2018. Retrieved June 6, 2008.