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 In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data buses of ...

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 circu ...

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 he ...

for the

Nintendo Entertainment System The Nintendo Entertainment System (NES) is an 8-bit third-generation home video game console produced by Nintendo. It was first released in Japan in 1983 as the commonly known as the The NES, a redesigned version, was released in American ...

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 proces ...

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''.

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 In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used fo ...

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 DMA may refer to: Arts * ''DMA'' (magazine), a defunct dance music magazine * Dallas Museum of Art, an art museum in Texas, US * Danish Music Awards, an award show held in Denmark * BT Digital Music Awards, an annual event in the UK * Doctor of M ...

, 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 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 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