The Ricoh 5A22 is an 8/16-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 ...
produced 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
Super Nintendo Entertainment System
The Super Nintendo Entertainment System, commonly shortened to Super Nintendo, Super NES or SNES, is a Fourth generation of video game consoles, 16-bit home video game console developed by Nintendo that was released in 1990 in Japan, 1991 in No ...
(SNES)
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 is based on the 8/16-bit
WDC WDC may refer to:
Organizations
* Western Defense Command, a U.S. Army formation during World War II
* Western Design Center, a U.S. microprocessor company
* Western Digital Corporation (NASDAQ: WDC), an American disk drive manufacturer
* Whale and ...
65C816
The W65C816S (also 65C816 or 65816) is a 16-bit microprocessor (MPU) developed and sold by the Western Design Center (WDC). Introduced in 1985, the W65C816S is an enhanced version of the WDC 65C02 8-bit MPU, itself a CMOS enhancement of the vener ...
, which was developed between 1982 and 1984 for the
Apple IIGS
The Apple IIGS (styled as II) is a 16-bit personal computer produced by Apple Inc., Apple Computer beginning in September 1986. It is the fifth and most powerful model of the Apple II family. The "GS" in the name stands for "Graphics and Sound" ...
personal computer. It has 92 instructions, an 8-bit
data bus
In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...
, a
16-bit
16-bit microcomputers are microcomputers that use 16-bit microprocessors.
A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...
accumulator, and a 24-bit
address bus
In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...
. The CPU runs between 1.79 MHz and 3.58 MHz, and uses an extended
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 ...
instruction set
In computer science, an instruction set architecture (ISA) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. A device or program that executes instructions described by that ISA, s ...
.
Major features
In addition to the
65C816
The W65C816S (also 65C816 or 65816) is a 16-bit microprocessor (MPU) developed and sold by the Western Design Center (WDC). Introduced in 1985, the W65C816S is an enhanced version of the WDC 65C02 8-bit MPU, itself a CMOS enhancement of the vener ...
CPU core, the 5A22 contains support hardware, including:
* Controller port interface circuits, including
serial access to controller data
* An 8-bit parallel I/O port, which is mostly unused in the SNES
* Circuitry for generating
non-maskable interrupt
In computing, a non-maskable interrupt (NMI) is a hardware interrupt that standard interrupt-masking techniques in the system cannot ignore. It typically occurs to signal attention for non-recoverable hardware errors. Some NMIs may be masked, but ...
s on
V-blank
* Circuitry for generating
interrupt
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted ...
s on calculated screen positions
* A
DMA
DMA may refer to:
Arts
* ''DMA'' (magazine), a defunct dance music magazine
* Dallas Museum of Art, in Texas, US
* BT Digital Music Awards, an annual event in the UK
* Danish Music Awards
* Detroit Music Awards
* Doctor of musical arts, a degree ...
unit, supporting two primary modes:
** General DMA, for block transfers at a rate of 2.68 MB/s
**
H-blank DMA, for transferring small data sets at the end of each
scanline
A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode-ray tube (CRT) display of a television set or computer monitor.
On CRT screens the horizontal scan lines are visually discernib ...
outside of the
active display period
*
Multiplication
Multiplication is one of the four elementary mathematical operations of arithmetic, with the other ones being addition, subtraction, and division (mathematics), division. The result of a multiplication operation is called a ''Product (mathem ...
and
division registers
* Two separate
address bus
In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...
ses driving the 8-bit
data bus
In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...
: a 24-bit "Bus A" for general access, and an 8-bit "Bus B" mainly for APU and PPU
registers
Performance
The CPU as a whole employs a variable-speed
system bus
A system bus is a single computer bus that connects the major components of a computer system,
combining the functions of a data bus to carry information, an address bus to determine where it should be sent or read from, and a control bus to det ...
, with bus access times determined by the memory location accessed. The bus runs at 3.58 MHz for non-access cycles and when accessing Bus B and most internal registers, and either 2.68 or 3.58 MHz when accessing Bus A. It runs at 1.79 MHz only when accessing the controller port serial-access registers.
It works at approximately 1.5
MIPS, and has a theoretical peak performance of 1.79 million 16-bit operations per second.
See also
*
Super Nintendo Entertainment System technical specifications
*
Nintendo SA-1
The list of Super NES enhancement chips demonstrates Nintendo hardware designers' plan to easily expand the Super Nintendo Entertainment System with special coprocessors. This standardized selection of chips was available to licensed developers, t ...
, a co-processor for the SNES based on the same 65C816 CPU core
References
Super Nintendo Entertainment System
Nintendo chips
65xx microprocessors
Ricoh products
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