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.
|Max. CPU clock rate||1.79 MHz|
|Architecture and classification|
|Min. feature size||6 μm|
|Instruction set||MOS 6502|
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), rudimentary DMA, and game controller polling.
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.
- Sattler, Christian. "Nintendo RP2A03 and RP2A07 - an high quality picture of the die". visual6502.org. Retrieved 2020-08-12..
- "Sound generators of the 1980s home computers". www.atkinsoft.com. Retrieved 2019-12-02.
- Taylor, Brad (April 23, 2004). "2A03 technical reference". NesDev.com. Archived from the original on October 17, 2018. Retrieved June 6, 2008.
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