The Ricoh 2A03 or RP2A03 (

NTSC NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170. In 1953, a second ...

version) / Ricoh 2A07 or RP2A07 ( PAL version) is an 8-bit

microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...

manufactured by

Ricoh is a Japanese multinational imaging and electronics company. It was founded by the now-defunct commercial division of the Institute of Physical and Chemical Research (Riken) known as the ''Riken Concern'', on 6 February 1936 as . Ricoh's hea ...

for the

Nintendo Entertainment System The Nintendo Entertainment System (NES) is an 8-bit home video game console developed and marketed by Nintendo. It was first released in Japan on 15 July 1983 as the and was later released as the redesigned NES in several test markets in the ...

video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can typically be played with a game controller. These may be home video game console, home consoles, which are generally ...

. It was also used as a sound chip and secondary CPU by

Nintendo is a Japanese Multinational corporation, multinational video game company headquartered in Kyoto. It develops, publishes, and releases both video games and video game consoles. The history of Nintendo began when craftsman Fusajiro Yamauchi ...

arcade game An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily game of skill, games of skill and in ...

s ''

Punch-Out!! is a boxing video game series created by Genyo Takeda, and published by Nintendo. The player controls Little Mac, a boxer who aims to become the World Video Boxing Association (W.V.B.A.) champion. The original '' Punch-Out!!'' arcade game w ...

'' and '' Donkey Kong 3''.

Technical details

The Ricoh 2A03. contains an unlicensed derivative of the

MOS Technology 6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit computing, 8-bit microprocessor that was desi ...

core, modified to disable the 6502's binary-coded decimal mode (possibly to avoid a MOS Technology patent). It also integrates a programmable sound generator (also known as APU, featuring twenty two

memory-mapped I/O Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer (often mediating access via chipset). An altern ...

registers), rudimentary DMA, and game controller polling.

Sound hardware

The Ricoh 2A03's sound hardware has 5 channels, separated into two APUs (Audio Processing Units). The first APU contains two general purpose pulse channels with 4 duty cycles, and the second APU contains a triangle wave generator, an LFSR-based Noise generator, and a 1-bit Delta modulation-encoded PCM (DPCM) channel. While a majority of the NES library uses only 4 channels, later games use the 5th DPCM channel due to cartridge memory expansions becoming cheaper. For example, Super Mario Bros. 3 uses the DPCM channel for simple drum sounds. An interesting quirk of the DPCM channel is that the bit order is reversed compared to what is normally expected for 1-bit PCM. Many developers were unaware of this detail, causing samples to be distorted during playback. The output of each channel is mixed non-linearly in their respective APU before being combined. On Famicom and Dendy systems, expansion sound chips may add their own sound to the output via a pin on the game cartridge. Expansion audio capabilities were removed from international NES systems, but can be restored by modifying the expansion port located on the bottom of the system.

Regional variations

PAL versions of the NES (sold in Europe, Asia, and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

) use the Ricoh 2A07 or RP2A07 processor, which is a 2A03 with modifications to better suit the 50 Hz vertical refresh rate used in the PAL television standard. However, most developers lacked the resources to properly adjust their games' music from NTSC to PAL, leading to many PAL games sounding slower, slightly lower-pitched, and in some cases, out-of-tune compared to their original NTSC releases.

References

{{Nintendo hardware Nintendo chips Ricoh products 65xx microprocessors Sound chips

Technical details

Sound hardware

Regional variations

See also

References