There are currently no mainstream general-purpose

processors Processor may refer to: Computing Hardware * Processor (computing) ** Central processing unit (CPU), the hardware within a computer that executes a program *** Microprocessor, a central processing unit contained on a single integrated circuit ( ...

built to operate on 256-bit integers or addresses, though a number of processors do operate on 256-bit data.

Representation

A 256-bit quantity can store 2²⁵⁶ different values. The range of

integer An integer is the number zero (0), a positive natural number (1, 2, 3, ...), or the negation of a positive natural number (−1, −2, −3, ...). The negations or additive inverses of the positive natural numbers are referred to as negative in ...

values that can be stored in 256 bits depends on the integer representation used. The range of a signed 256-bit integer is from to . 256-bit processors could be used for addressing directly up to 2²⁵⁶ bytes. Already 2¹²⁸ (for

128-bit General home computing and gaming utility emerged at 8-bit word sizes, as 28=256 Word (computer architecture), words, a natural unit of data, became possible. Early 8-bit CPUs (such as the Zilog Z80 and MOS Technology 6502, used in the 1977 Co ...

addressing) would greatly exceed the total data stored on Earth as of 2018, which has been estimated to be around 33.3 ZBs (over 2⁷⁴ bytes).

History

Xbox 360 The Xbox 360 is a home video game console developed by Microsoft. As the successor to the Xbox (console), original Xbox, it is the second console in the Xbox#Consoles, Xbox series. It was officially unveiled on MTV on May 12, 2005, with detail ...

was the first high-definition gaming console to utilize the

ATI Technologies ATI Technologies Inc. was a Canadian semiconductor industry, semiconductor technology corporation based in Markham, Ontario, that specialized in the development of graphics processing units and chipsets. Founded in 1985, the company listed pub ...

256-bit GPU Xenos before the introduction of the current gaming consoles especially

Nintendo Switch The is a video game console developed by Nintendo and released worldwide in most regions on March 3, 2017. Released in the middle of the Eighth generation of video game consoles, eighth generation of home consoles, the Switch succeeded the ...

. Some buses on the newer

System on a chip A system on a chip (SoC) is an integrated circuit that combines most or all key components of a computer or Electronics, electronic system onto a single microchip. Typically, an SoC includes a central processing unit (CPU) with computer 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 pr ...

developed by

Nvidia Nvidia Corporation ( ) is an American multinational corporation and technology company headquartered in Santa Clara, California, and incorporated in Delaware. Founded in 1993 by Jensen Huang (president and CEO), Chris Malachowsky, and Curti ...

) utilize 64-bit, 128-bit, 256-bit, or higher.

Hardware

CPUs feature

SIMD Single instruction, multiple data (SIMD) is a type of parallel computer, parallel processing in Flynn's taxonomy. SIMD describes computers with multiple processing elements that perform the same operation on multiple data points simultaneousl ...

instruction sets (

Advanced Vector Extensions Advanced Vector Extensions (AVX, also known as Gesher New Instructions and then Sandy Bridge New Instructions) are SIMD extensions to the x86 instruction set architecture for microprocessors from Intel and Advanced Micro Devices (AMD). They w ...

and the

FMA instruction set The FMA instruction set is an extension to the 128- and 256-bit Streaming SIMD Extensions instructions in the x86 microprocessor instruction set to perform fused multiply–add (FMA) operations. There are two variants: * FMA4 is supported in ...

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), ...

s are used to store several smaller numbers, such as eight 32-bit

floating-point In computing, floating-point arithmetic (FP) is arithmetic on subsets of real numbers formed by a ''significand'' (a Sign (mathematics), signed sequence of a fixed number of digits in some Radix, base) multiplied by an integer power of that ba ...

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

collections. Modern GPU chips may operate data across a 256-bit memory bus (or possibly a 512-bit bus with HBM3). The

Efficeon The Efficeon (stylized as efficēon) processor is Transmeta's second-generation 256-bit VLIW design released in 2004 which employs a software engine Code Morphing Software (CMS) to convert code written for x86 processors to the native instructi ...

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 ...

's second-generation 256-bit

VLIW Very long instruction word (VLIW) refers to instruction set architectures that are designed to exploit instruction-level parallelism (ILP). A VLIW processor allows programs to explicitly specify instructions to execute in parallel computing, para ...

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 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...

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 Adva ...

funded Data-Intensive Architecture (DIVA) system incorporated processor-in-memory (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 In cryptography, key size or key length refers to the number of bits in a key used by a cryptographic algorithm (such as a cipher). Key length defines the upper-bound on an algorithm's security (i.e. a logarithmic measure of the fastest known a ...

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 ...

s in

cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...

, 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

. * Researchers at the

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

use a 256-bit capability pointer, which includes capability and addressing information, on early implementations of their CHERI capability system. *

SHA-256 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compressi ...

hash function. *

Smart contract A smart contract is a computer program or a Transaction Protocol Data Unit, 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 objective ...

s use 256- or 257-bit integers; 256-bit words for the Ethereum Virtual Machine. "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." * The Zig programming language has built-in support for signed and unsigned arbitrary bit-width integers for all supported platforms, including 256-bit. The calling convention for exported functions using such integers however, has not been specified in ABIs.

References

{{Processor technologies Data unit

Representation

History

Hardware

Software

See also

References