256-bit computing

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In computer architecture, 256-bit integers, memory addresses, or other data units are those that are 256 bits (32 octets) wide. Also, 256-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.

There are currently no mainstream general-purpose processors built to operate on 256-bit integers or addresses, though a number of processors do operate on 256-bit data. CPUs feature SIMD instruction sets (Advanced Vector Extensions and the FMA instruction set etc.) where 256-bit vector registers are used to store several smaller numbers, such as eight 32-bit floating-point 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 collections.

A 256-bit register can store 2256 different values. The range of integer values that can be stored in 256 bits depends on the integer representation used.

The maximum value of an unsigned 256-bit integer is 2256 − 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.


Laptop computer using an Efficeon processor


The DARPA 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.[5]

See also[edit]


  1. ^ Miller, Rich (4 May 2010). "Digital Universe nears a Zettabyte". Data Center Knowledge. Archived from the original on 6 May 2010. Retrieved 16 September 2010.
  2. ^ "Transmeta Efficeon TM8300 Processor" (PDF). Transmeta Corporation. Archived (PDF) from the original on 10 February 2019.
  3. ^ Williams, Martyn (29 May 2002). "Transmeta Unveils Plans for TM8000 Processor". PC World. Archived from the original on 14 April 2010.
  4. ^ Watson, Robert N. M.; Neumann, Peter G.; Woodruff, Jonathan; Anderson, Jonathan; Anderson, Ross; Dave, Nirav; Laurie, Ben; Moore, Simon W.; Murdoch, Steven J.; Paeps, Philip; Roe, Michael; Saidi, Hassen (3 March 2012). "CHERI: a research platform deconflating hardware virtualization and protection" (PDF). Unpublished workshop paper for RESoLVE’12, March 3, 2012, London, UK. SRI International Computer Science Laboratory.
  5. ^ Draper, Jeffrey; Sondeen, Jeff; Chang Woo Kang (October 2002). Implementation of a 256-bit WideWord Processor for the Data-Intensive Architecture (DIVA) Processing-In-Memory (PIM) Chip (PDF). International Solid-State Circuits Conference. Archived (PDF) from the original on 29 August 2017.