Editing Nibble (section)

== History ==
The term ''nibble'' originates from its representing "half a byte", with ''byte'' a [[homophone]] of the [[English (language)|English]] word ''bite''.<ref name="esr"/> In 2014, David B. Benson, a professor emeritus at [[Washington State University]], remembered that he playfully used (and may have possibly coined) the term ''nibble'' as "half a byte" and unit of storage required to hold a [[binary-coded decimal]] (BCD) digit around <!-- 1957 or -->1958, when talking to a programmer from [[Los Alamos Scientific Laboratory]]. The alternative spelling ''nybble'' reflects the spelling of ''byte'', as noted in editorials of ''[[Kilobaud Microcomputing|Kilobaud]]'' and ''[[Byte (magazine)|Byte]]'' in the early 1980s. Another early recorded use of the term ''nybble'' was in 1977 within the consumer-banking technology group at Citibank. It created a pre-[[ISO 8583]] standard for transactional messages between [[cash machine]]s and Citibank's [[data center]]s that used the basic data unit 'nabble'.

''Nibble'' is used to describe the amount of memory used to store a digit of a number stored in [[binary-coded decimal|packed decimal format]] (BCD) within an IBM mainframe. This technique is used to make computations faster and debugging easier. An 8-bit byte is split in half and each nibble is used to store one decimal digit. The last (rightmost) nibble of the variable is reserved for the sign. Thus a variable which can store up to nine digits would be "packed" into 5 bytes. Ease of debugging resulted from the numbers' being readable in a [[hex dump]] where two [[hexadecimal|hex]] numbers are used to represent the value of a byte, as {{math|16×16 {{=}} 2<sup>8</sup>}}. For example, a five-byte BCD value of {{code|31}}&nbsp;{{code|41}}&nbsp;{{code|59}}&nbsp;{{code|26}}&nbsp;{{code|5C}} represents a decimal value of +314159265.

Historically, there are cases where ''nybble'' was used 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-and-3 encoding|5-bit]] (later, [[6-and-2 encoding|6-bit]]) nibbles and loading disk data required the reverse.<ref name="Lechner_1982_Beneath_Apple_DOS"/><ref name="Lechner_1985_Beneath_Apple_ProDOS"/><ref name="CP_1989_CopyII"/> Moreover, 1982 documentation for the [[Integrated Woz Machine]] refers consistently to an "8 bit nibble".<ref name="Apple_1982_IWM"/> The term ''byte'' once had the same ambiguity and meant a set of bits but not necessarily 8, hence the distinction of ''bytes'' and ''[[octet (computing)|octet]]s'' 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.