Ricoh 2A03 [SEP] manufacturer
Ricoh 2A03
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 contained a second sourced MOS Technology 6502 core, modified to disable the 6502's binary-coded decimal mode, with 22 memory-mapped I/O registers that controlled an APU, rudimentary DMA, and game controller polling. It was also used as a sound chip and secondary CPU by Nintendo's arcade games "Punch-
Out!!" and "Donkey Kong 3".
Regional variations.
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