There are currently no mainstream general-purpose
processors
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...
built to operate on 256-bit integers or addresses, though a number of processors do operate on 256-bit data.
Representation
A 256-bit register can store 2
256 different values. The range of
integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the language ...
values that can be stored in 256 bits depends on the
integer representation used.
The maximum value of an unsigned 256-bit integer is 2
256 − 1, written in decimal as 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,935 or approximately as 1.1579 x 10
77.
256-bit processors could be used for addressing directly up to 2
256 bytes. Already 2
128 (for
128-bit
While there are currently no mainstream general-purpose processors built to operate on 128-bit ''integers'' or addresses, a number of processors do have specialized ways to operate on 128-bit chunks of data.
Representation
128-bit processors co ...
addressing) would greatly exceed the total data stored on Earth as of 2018, which has been estimated to be around 33.3
zettabyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
s (over 2
75 bytes).
History
Xbox 360
The Xbox 360 is a home video game console developed by Microsoft. As the successor to the original Xbox, it is the second console in the Xbox series. It competed with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation ...
was the first high-definition gaming console to utilize the
ATI Technologies 256-bit GPU
Xenos before the introduction of the current gaming consoles especially
Nintendo Switch
The is a hybrid video game console developed by Nintendo and released worldwide in most regions on March 3, 2017. The console itself is a Tablet computer#Gaming tablet, tablet that can either be docking station, docked for use as a home video ...
.
Some buses on the newer
System on a chip
A system on a chip or system-on-chip (SoC ; pl. ''SoCs'' ) is an integrated circuit that integrates most or all components of a computer or other electronic system. These components almost always include a central processing unit (CPU), memory ...
(e.g.
Tegra
Tegra is a system on a chip (SoC) series developed by Nvidia for mobile devices such as smartphones, personal digital assistants, and mobile Internet devices. The Tegra integrates an ARM architecture central processing unit (CPU), graphics proc ...
developed by
Nvidia
Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as VIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as VIDIA with a large italicized lowercase "n" on products from the mid 1990s to ...
) utilize 64-bit, 128-bit, 256-bit, or higher.
Hardware
![Sharp PC-MM2 frontal view](https://upload.wikimedia.org/wikipedia/commons/4/42/Sharp_PC-MM2_frontal_view.jpg)
CPUs feature
SIMD instruction sets (
Advanced Vector Extensions and the
FMA instruction set etc.) where 256-bit vector
register
Register or registration may refer to:
Arts entertainment, and media Music
* Register (music), the relative "height" or range of a note, melody, part, instrument, etc.
* ''Register'', a 2017 album by Travis Miller
* Registration (organ), the ...
s are used to store several smaller numbers, such as eight 32-bit
floating-point
In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can b ...
numbers, and a single
instruction can operate on all these values in parallel. However, these processors do not operate on individual numbers that are 256 binary digits in length, only their
registers have the size of 256-bits. Binary digits are found together in
128-bit
While there are currently no mainstream general-purpose processors built to operate on 128-bit ''integers'' or addresses, a number of processors do have specialized ways to operate on 128-bit chunks of data.
Representation
128-bit processors co ...
collections.
Modern
GPU chips may operate data across a 256-bit memory bus (or possibly a
512-bit
There are currently no mainstream general-purpose CPU, processors built to operate on 512-bit integers or addresses, though a number of processors do operate on 512-bit data.
Representation
A 512-bit register can store 2512 different values. The ...
bus with
HBM3
High Bandwidth Memory (HBM) is a high-speed computer memory interface for 3D-stacked synchronous dynamic random-access memory (SDRAM) initially from Samsung, AMD and SK Hynix. It is used in conjunction with high-performance graphics accelerators ...
).
The
Efficeon processor was
Transmeta
Transmeta Corporation was an American fabless semiconductor company based in Santa Clara, California. It developed low power x86 compatible microprocessors based on a VLIW core and a software layer called Code Morphing Software.
Code Morphing So ...
's second-generation 256-bit
VLIW design which employed a software engine to convert code written for
x86
x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...
processors to the native instruction set of the chip.
The
DARPA
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military.
Originally known as the Adv ...
funded Data-Intensive Architecture (DIVA) system incorporated
processor-in-memory
Computational RAM (C-RAM) is random-access memory with processing elements integrated on the same chip. This enables C-RAM to be used as a SIMD computer. It also can be used to more efficiently use memory bandwidth within a memory chip.
Overview ...
(PIM) 5-stage
pipelined 256-bit datapath, complete with register file and ALU blocks in a "WideWord" processor in 2002.
Software
* 256 bits is a common
key size for
symmetric cipher
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between th ...
s in
cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...
, such as
Advanced Encryption Standard
The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001.
AES is a variant ...
(AES).
* Increasing the word size can accelerate
multiple precision mathematical libraries. Applications include
cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...
.
* Researchers at the
University of Cambridge
, mottoeng = Literal: From here, light and sacred draughts.
Non literal: From this place, we gain enlightenment and precious knowledge.
, established =
, other_name = The Chancellor, Masters and Schola ...
use a 256-bit capability pointer, which includes capability and addressing information, on early implementations of their CHERI capability system.
*
SHA-256 hash function.
*
Smart contract
A smart contract is a computer program or a transaction protocol that is intended to automatically execute, control or document events and actions according to the terms of a contract or an agreement. The objectives of smart contracts are the re ...
s use 256- or 257-bit integers; 256-bit words for the
Ethereum Virtual Machine
Ethereum is a decentralized, open-source blockchain with smart contract functionality. Ether ( Abbreviation: ETH; sign: Ξ) is the native cryptocurrency of the platform. Among cryptocurrencies, ether is second only to bitcoin in market ...
. "We realize that a 257 bits byte is quite unusual, but for smart contracts it is ok to have at least 256 bits numbers. The leading VM for smart contracts, Ethereum VM, introduced this practice and other blockchain VMs followed."
See also
*
Berkeley IRAM project The Berkeley IRAM project was a 1996–2004 research project in the Computer Science Division of the University of California, Berkeley which explored computer architecture enabled by the wide bandwidth between memory and processor made possible ...
*
Computational RAM
Computational RAM (C-RAM) is random-access memory with central processing unit, processing elements integrated on the same chip. This enables C-RAM to be used as a SIMD computer. It also can be used to more efficiently use memory bandwidth within ...
References
{{Processor technologies
Data unit