The Ricoh 2A03 or RP2A03 (

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

version) / Ricoh 2A07 or RP2A07 (

PAL Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

version) is an 8-bit

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...

manufactured by

Ricoh is a Japanese Multinational corporation, multinational imaging and electronics company (law), company. It was founded by the now-defunct commercial division of the Riken, Institute of Physical and Chemical Research (Riken) known as the ''Riken ...

for the Nintendo Entertainment System

video game console A video game console is an electronic device that outputs a video signal or image to display a video game that can be played with a game controller. These may be home consoles, which are generally placed in a permanent location connected to ...

. It was also used as a

sound chip A sound chip is an integrated circuit (chip) designed to produce audio signals through digital, analog or mixed-mode electronics. Sound chips are typically fabricated on metal–oxide–semiconductor (MOS) mixed-signal chips that process ...

and secondary CPU by Nintendo's arcade games ''

Punch-Out!! is a video game series of boxing created by Nintendo's general manager Genyo Takeda, and his partner Makoto Wada. The first game was '' Punch-Out!!'' made in 1984 as an arcade unit, which was followed by a sequel '' Super Punch-Out!!'' (1984) ...

'' and ''

Donkey Kong 3 is a platform shooter video game developed and published by Nintendo. It is the third installment in the ''Donkey Kong'' series and it was released for arcades worldwide in 1983 and the Family Computer in 1984, then later released in North Am ...

''.

Technical details

The Ricoh 2A03. contains a second-sourced

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 microprocessor that was designed by a small te ...

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. An alternative approach is using dedicated I/O pr ...

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 In computing, a linear-feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state. The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a sh ...

-based Noise generator, and a 1-bit

Delta modulation A delta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance. DM is the simplest form of differential puls ...

-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, while

Journey to Silius ''Journey to Silius'', known in Japan as , is a side-scrolling run and gun video game developed and published by Sunsoft for the Nintendo Entertainment System in 1990. ''Journey to Silius'' was originally based on the 1984 film '' The Termin ...

uses it for sampled basslines. 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) 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