128-bit
From Freepedia
| N-bit Processors | ||||||||
|---|---|---|---|---|---|---|---|---|
| 4-bit | 8-bit | 16-bit | 24-bit | 31-bit | 32-bit | 48-bit | 64-bit | 128-bit |
| N-bit Applications | ||||||||
| 16-bit | 31-bit | 32-bit | 64-bit | |||||
| N-bit Data Sizes | ||||||||
| 4-bit | 8-bit | 16-bit | 32-bit | 64-bit | 128-bit | |||
| nibble byte octet word dword qword | ||||||||
| These definitions are relevant to the world of x86 processors. See linked articles for discussion of the meaning in other architectures. The 31-bit and 48-bit sizes relate to IBM mainframes and AS/400s, respectively. | ||||||||
In computer architecture, 128-bit is an adjective used to describe integers, memory addresses or other data units that are at most 128 bits wide, or to describe CPU and ALU architectures based on registers, address buses, or data buses of that size. There are currently no mainstream general-purpose processors built to facilitate 128-bit instruction sets and operations, as 128-bit requires a buffer memory size and throughput width double the size of 64-bit processors, and 128-bit capable processors far exceed practical needs. 64-bit processors today suffice more than enough.
System/370, made by IBM, is possibly 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 registers 128 bits wide—they load and store memory in units of 128 bits—but they do not operate on single numbers that are 128 binary digits in length.
128-bit processors may become prevalent when 264 bytes of addressable memory is no longer enough. It might turn out to be more efficient to connect (relatively) little memory to a large number of processors, than a lot of memory shared among them. Most supercomputers are comprised of either many 32-bit processors or 64-bit processors linked together, with instructions being executed simultaneously across those processors.
