Ricoh 2A03
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| Produced | From 1982 to 1994 |
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| Common manufacturer(s) | |
| Max. CPU clock rate | 1.79 MHz |
| Min. feature size | 6 μm |
| Instruction set | MOS 6502 |
| Cores | 1 |
| Socket(s) |
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The Ricoh 2A03 or RP2A03 (NTSC version) / Ricoh 2A07 or RP2A07 (PAL version) is the 8-bit microprocessor in the Nintendo Entertainment System video game console manufactured by Ricoh. It contained a second source 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.
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.
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