About
A word is a fixed-sized piece of data processed as a unit by the processor. The word size is defined in the instruction set architecture.
The term word is used for a small group of bits that are handled simultaneously by processor of a particular architecture.
A word is stored in memory one byte at a time.
The following component in a computer have generally the size of word:
- the largest system bus size (the largest piece of data that can be transferred to and from the working memory)
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Properties
Size
It determines the unit of processing of the whole computer. ie for:
- The CPU, see CPU - Word size (8, 16, 32 and 64-bit)
- The bus, see system bus
Byte order
When a word is greater than one byte and therefore needs to be split in order to be stored in memory, the part are stored in a order called endianess. Words may be represented in big-endian or little-endian format. Memory - Byte Order - (Endian-ness) of a Word
Example of 32 bits long word
Full
A 32 bits register is called a fullword.
Data Type
integer max size is on some computer define by the size of a word.
This limitation may cause programs to crash. For example, if a programmer using the C language incorrectly declares as int a variable that will be used to store values greater than <math>2^{15}−1</math> , the program will fail on computers with 16-bit integers. That variable should have been declared as long, which has at least 32 bits on any computer.