128-bit
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| Microprocessors | ||||||||
|---|---|---|---|---|---|---|---|---|
| 4-bit | 8-bit | 16-bit | 24-bit | 31-bit | 32-bit | 48-bit | 64-bit | 128-bit |
| Applications | ||||||||
| 8-bit | 16-bit | 31-bit | 32-bit | 64-bit | ||||
| Data Sizes | ||||||||
| 4-bit | 8-bit | 16-bit | 32-bit | 64-bit | 128-bit | |||
| nibble byte octet word dword qword | ||||||||
In computer architecture, 128-bit integers, memory addresses, or other data units are those that are at most 128 bits wide. Also, 128-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 128-bit (16 octets) integers or addresses, though a number of processors do operate on 128-bit data. System/370, made by IBM, could be considered the first rudimentary 128-bit computer as it used 128-bit floating point registers. Most modern CPUs such as the Pentium and PowerPC have 128-bit vector registers used to store several smaller numbers, such as 4 32-bit floating-point numbers. A single instruction can operate on all these values in parallel (SIMD). They are 128-bit processors in the sense that they have 128-bit registers and in some cases a 128-bit ALU, but they do not operate on individual numbers that are 128 binary digits in length.
[edit] Uses
- IPv6 addresses are 128 bits wide. Having a processor capable of manipulating 128-bit integers could simplify handling of IPv6 addresses, since addresses could be stored in a single register, much as IPv4 addresses are stored now. See also RFC 1924 section 7.
- 128-bits is a common key size for symmetric ciphers in cryptography.
- 128-bit processors could become prevalent when 16 exbibytes (264, approximately 1.8 x 1019, bytes) of addressable memory is no longer enough. However, even if Moore's law were to apply to memory size (and probably also memory access speeds) in the years to come — a big assumption — it would still take a long time to exhaust a 64-bit address space. A doubling of memory capacity requires one extra address bit. Considering that large servers available in mid-2006 (example: IBM System z9 Enterprise Class) contain 512 GiB of RAM (thus requiring at least 39-bit addresses), then a 64-bit address space should be sufficient for another 50 years. Some form of bank switching could extend the useful life of 64-bit addressing even beyond that. For comparison, electronic computing was invented only about 60 years ago.
- PlayStation 2 computer entertainment system's Emotion Engine CPU is a 128-bit processor.
- ZFS is a 128-bit file system.
- The AS/400 instruction set defines all pointers as 128-bit.
