byte
<unit> /bi:t/ (B) A component in the machine data hierarchy usually
larger than a bit and smaller than a word; now most often eight bits and the
smallest addressable unit of storage. A byte typically holds one character.
A byte may be 9 bits on 36-bit computers. Some older architectures used "byte"
for quantities of 6 or 7 bits, and the PDP-10 and IBM 7030 supported "bytes"
that were actually bit-fields of 1 to 36 (or 64) bits! These usages are now
obsolete, and even 9-bit bytes have become rare in the general trend toward
power-of-2 word sizes.
The term was coined by Werner Buchholz in 1956 during the early design phase for
the IBM Stretch computer. It was a mutation of the word "bite" intended to avoid
confusion with "bit". In 1962 he described it as "a group of bits used to encode
a character, or the number of bits transmitted in parallel to and from
input-output units". The move to an 8-bit byte happened in late 1956, and this
size was later adopted and promulgated as a standard by the System/360 operating
system (announced April 1964).
James S. Jones <jsjones@graceland.edu> adds:
I am sure I read in a mid-1970's brochure by IBM that outlined the history of
computers that BYTE was an acronym that stood for "Bit asYnchronous Transmission
E__?__" which related to width of the bus between the Stretch CPU and its
CRT-memory (prior to Core).
Terry Carr <bear@mich.com> says:
In the early days IBM taught that a series of bits transferred together (like so
many yoked oxen) formed a Binary Yoked Transfer Element (BYTE).
[True origin? First 8-bit byte architecture?]
See also nibble, octet.
[Jargon File]
(2003-09-21)
Nearby terms:
byacc « by hand « Byte « byte » byte-code »
byte-code compiler » byte-code interpreter
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