This is an old revision of this page, as edited by Wtshymanski (talk | contribs) at 15:47, 13 April 2005 (Half-width data busses). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 15:47, 13 April 2005 by Wtshymanski (talk | contribs) (Half-width data busses)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)In computer hardware terminology, word size (word length) is the number of bits that a CPU can process at one time (the word). Processors with many different word sizes have existed, where the word size was selected as a trade off between precision and range of numeric results and the cost of the processing hardware. A 12-bit data word was common on early minicomputers and is still used on special-purpose microprocessors. Some early mainframe systems used 36-bit words. Word lengths in powers of two (8, 16, 32, 64) have predominated for many years, roughly since the introducionn of the IBM System 360. See 8-bit, 16-bit, 32-bit, 64-bit, 128-bit.
A processor's word size for arithmentic is often equal to the width of its external data bus though sometimes the bus is made narrower than the CPU (often half as many bits) to economise on packaging and circuit board costs, space, and power consumption.
A word n bits long can hold 2 distinct values. If these values represent integers, by far the most common ranges are −2 to 2−1 inclusive, or 0 to 2−1 inclusive.
This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.
Categories: