<
unit> /bi:t/ (B) A component in the machine
data hierarchy
larger than a
bit and usually smaller than a
word; now
nearly always 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)