Nibble

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Nibble

A nibble (often, nybble) is the computing

Computing

Computing is usually defined as the activity of using and developing computer technology, computer hardware and computer software. It is the computer-specific part of information technology....
term for a four-bit

Bit

A bit is a binary numeral system numerical digit, taking a value of either 0 or 1. Binary digits are a basic unit of information Computer data storage and transmission in digital computing and digital information theory....
aggregation, or half an octet

Octet (computing)

In computing, an octet is a grouping of eight bits.Octet, with the only exception noted below, always refers to an entity having exactly eight bits....
(an octet being an 8-bit

8-bit

Eight-bit CPUs normally use an 8-bit data bus and a 16-bit address bus which means that their address space is limited to 64 KBs. This is not a "natural law", however, so there are exceptions....
byte

Byte

A byte is a basic unit of measurement of Computer storage in computer science. In many computer architectures it is a Byte addressing memory address space....
). As a nibble contains 4 bits, there are sixteen (2⁴) possible values, so a nibble corresponds to a single hexadecimal

Hexadecimal

In mathematics and computer science, hexadecimal is a numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen....
digit (thus, it is often referred to as a "hex digit" or "hexit").

A full byte (octet

Octet (computing)

In computing, an octet is a grouping of eight bits.Octet, with the only exception noted below, always refers to an entity having exactly eight bits....
) is represented by two hexadecimal digits; therefore, it is common to display a byte of information as two nibbles.

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Encyclopedia

A nibble (often, nybble) is the computing

Computing

Bit

Octet (computing)

In computing, an octet is a grouping of eight bits.Octet, with the only exception noted below, always refers to an entity having exactly eight bits....
(an octet being an 8-bit

8-bit

Byte

Hexadecimal

Octet (computing)

Computer network

A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network....
or telecommunication

Telecommunication

Telecommunication is the assisted Transmission of Signal over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, Drum , Semaphore line, flag signals or heliograph....
context. Sometimes the set of all 256

256 (number)

256 is the natural number following 255 and preceding 257 ....
byte values is represented as a table 16

16 (number)

Sixteen is a composite number, and a square number, being 4 2 = 4 × 4. It is the smallest number with exactly five divisors, its proper divisors being , , and ....
×16, which gives easily readable hexadecimal codes for each value.

The term "nibble" originates from the fact that the term "byte" is a pun

Pun

A pun, or paronomasia, is a form of word play that deliberately exploits ambiguity between similar-sounding words for humour or rhetorical effect....
on the English word "bite". A nibble is a small bite, which in this context is construed as "half a bite". The alternative spelling "nybble" parallels the spelling of "byte", as noted in editorials in Kilobaud

Kilobaud Microcomputing

Kilobaud Microcomputing was a magazine dedicated to the Homebrew Computer Club hobbyists from the end of the 1970s until the beginning of the 1980s....
and Byte in the early eighties.

The nibble is used to describe the amount of memory used to store a digit of a number stored in packed decimal format

Binary-coded decimal

In computing and electronics systems, binary-coded decimal is an encoding for decimal numbers in which each digit is represented by its own binary sequence....
within an IBM mainframe. This technique is used to reduce space requirements, make computations faster, and make debugging easier. An 8-bit byte is split in half and each nibble is used to store one digit. The last 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

Hex dump

Hex dump is a hexadecimal view of computer memory. Each byte is represented as a two-digit hexadecimal number. Hex dumps are commonly organized into rows of 8 or 16 bytes, sometimes separated by whitespaces....
where two hex numbers are used to represent the value of a byte, as 16×16 = 2⁸.

Historically, there have been cases where the term "nybble" was used for a set of bits fewer than 8, but not necessarily 4. In the Apple II microcomputer line, much of the disk drive control was implemented in software. Writing data to a disk was done by converting 256-byte pages into sets of 5-bit or, later, 6-bit nibbles; loading data from the disk required the reverse. Note that the term byte also had this ambiguity; at one time, byte meant a set of bits but not necessarily 8. Today, the terms "byte" and "nibble" generally refer to 8- and 4-bit collections, respectively, and are not often used for other sizes. The term "semi-nibble" is used to refer to a 2-bit collection, or half a nibble.

The sixteen nibbles and their equivalents in other numeral systems:

Nibble

See also

External links