The term
nibble originates from its representing half a byte, with
byte a
homophone of the
English word
bite. In 1977, an early use of the spelling
nybble for the term was recorded within the consumer-banking technology group at Citibank. It created a pre-
ISO 8583 standard for transactional messages between
cash machines and Citibank's
data centers that used the basic data unit
nabble. In the early 1980s, the alternative spelling
nybble reflected the spelling of
byte, as noted in editorials of
Kilobaud and
Byte. Historically,
nybble was used in many cases for a group of bits greater than 4. On the
Apple II, much of the disk drive control and
group-coded recording was implemented in software. Writing data to a disk was done by converting 256-byte pages into sets of
5-bit (later,
6-bit) nibbles and loading disk data required the reverse. Moreover, 1982 documentation for the
Integrated Woz Machine refers consistently to an "8 bit nibble". The term
byte once had the same ambiguity and meant a set of bits but not necessarily 8, hence the distinction of
bytes and
octets or of
nibbles and
quartets (or
quadbits). Today, the terms
byte and
nibble almost always refer to 8-bit and 4-bit collections, respectively, and are very rarely used to express any other sizes. ==Part of a byte==