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AVK>Материал из Википедии — свободной энциклопедии
The word "byte" has several meanings, all closely related:
1. A contiguous sequence of a fixed number of bits. On modern computers, an eight-bit byte or octet is by far the most common. This was not always the case. Certain older models have used six-, seven-, or nine-bit bytes — for instance on the 36-bit architecture of the PDP-10. Another example of a non eight-bit sequence is the 12-bit slab of the NCR-315. A byte is always atomic on the system, meaning that it is the smallest addressable unit. An eight-bit byte can hold 256 possible values (28 = 256) -- enough to store an unsigned integer ranging from 0 to 255, a signed integer from -128 to 127, or a character of a seven-bit (such as ASCII) or eight-bit character encoding.
2. A contiguous sequence of bits that comprises a sub-field of a longer sequence known as a word. On some computers it is possible to address bytes of arbitrary length. This usage is reflected, for example, in LDB and DPB assembly instructions for field extraction on a PDP-10, which survive as bytewise operations in Common Lisp; and in the six-bit bytes of the IBM 1401.
3. A datatype or synonym for a datatype in certain programming languages. C, for example, defines byte as a storage unit capable of at least being large enough to hold any character of the execution environment (clause 3.5 of the C standard). Since the C char integral data type can hold at least 8 bits (clause 22.214.171.124.1), a byte in C is at least capable of holding 256 different values (signed or unsigned char doesn't matter). Java plays it simpler. Java's integral byte data type is always defined as consisting of 8 bits and being a signed data type, holding values from -128 to 127.
(с) Нормальная человеческая Wikipedia.