# Nibble

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Nibble
> Markdown URL: https://mediated.wiki/source/Nibble.md
> Source: https://en.wikipedia.org/wiki/Nibble
> Source revision: 1343148105
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Four-bit unit of binary data

This article is about the data storage unit. For other uses, see [Nibble (disambiguation)](/source/Nibble_(disambiguation)).

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Nibble" – news · newspapers · books · scholar · JSTOR (April 2015) (Learn how and when to remove this message)

An [octet](/source/Octet_(computing)) [code page 866](/source/Code_page_866) font table ordered by nibbles.

In [computing](/source/Computing), a **nibble**,[1] also spelled **nybble** to match [byte](/source/Byte), is a [unit of information](/source/Unit_of_information) that consists of four [bits](/source/Bit). A nibble is half of a [byte](/source/Byte), or [octet](/source/Octet_(computing)).[1][2][3] The unit is alternatively called **nyble**, **nybl**, **half-byte**[4] or **tetrade**.[5][6] In [networking](/source/Computer_network) or [telecommunications](/source/Telecommunications), the unit is often called a **semi-octet**,[7] **quadbit**,[8] or **quartet**.[9][10]

As a nibble can represent sixteen (24) possible values, a nibble value is often shown as a [hexadecimal](/source/Hexadecimal) [digit](/source/Digit_(math)) (hex digit).[11] A byte is two nibbles, and therefore, a value can be shown as two hex digits.

[Four-bit computers](/source/4-bit_computing) use nibble-sized data for storage and operations, in the form of the [word](/source/Word_(computer_architecture)) unit. Such computers were used in early [microprocessors](/source/Microprocessor), [pocket calculators](/source/Pocket_calculator) and [pocket computers](/source/Pocket_computer). They continue to be used in some [microcontrollers](/source/Microcontroller). In this context, 4-bit groups were sometimes also called [characters](/source/Character_(computing))[12] rather than nibbles.[1]

## History

The term *nibble* originates from its representing half a byte, with *byte* a [homophone](/source/Homophone) of the [English](/source/English_(language)) word *bite*.[4]

David B. Benson, at the time a [Washington State University](/source/Washington_State_University) professor, might have originated the term *nibble* in 1958 as a joke.[13]

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](/source/ISO_8583) standard for transactional messages between [cash machines](/source/Cash_machine) and Citibank's [data centers](/source/Data_center) that used the basic data unit *nabble*.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

In the early 1980s, the alternative spelling *nybble* reflected the spelling of *byte*, as noted in editorials of *[Kilobaud](/source/Kilobaud_Microcomputing)* and *[Byte](/source/Byte_(magazine))*.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

Historically, *nybble* was used in many cases for a group of bits greater than 4. On the [Apple II](/source/Apple_II), much of the disk drive control and [group-coded recording](/source/Group-coded_recording) was implemented in software. Writing data to a disk was done by converting 256-byte pages into sets of [5-bit](/source/5-and-3_encoding) (later, [6-bit](/source/6-and-2_encoding)) nibbles and loading disk data required the reverse.[14][15][16] Moreover, 1982 documentation for the [Integrated Woz Machine](/source/Integrated_Woz_Machine) refers consistently to an "8 bit nibble".[17] 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](/source/Octet_(computing))* 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.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

## Part of a byte

*Nibble* is used to describe the amount of memory used to store a digit of a number stored in [packed decimal format](/source/Binary-coded_decimal) (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 that 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](/source/Hex_dump) where two [hex](/source/Hexadecimal) numbers are used to represent the value of a byte, as 16×16 = 28. For example, a five-byte BCD value of 31 41 59 26 5C represents a decimal value of +314159265.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

Packed nibbles can also describe binary numbers. The low and high nibbles of a byte are its two halves, which are the least and the most significant bits within the byte, respectively.[18] For example in binary,

- ninety-seven = 9710 = (0110 0001)2

the high nibble is 01102 (616), and the low nibble is 00012. The total value is high-nibble × 1610 + low-nibble (6 × 16 + 1 = 9710).

## Value representation

A nibble-sized value can be represented in different numeric bases:

Binary Decimal Hexadecimal 0000 0 0 0001 1 1 0010 2 2 0011 3 3 0100 4 4 0101 5 5 0110 6 6 0111 7 7 1000 8 8 1001 9 9 1010 10 A 1011 11 B 1100 12 C 1101 13 D 1110 14 E 1111 15 F

## See also

- [Binary number](/source/Binary_number) – Number expressed in the base-2 numeral system

- [Syllable](/source/Syllable_(computing)) – Platform-specific data size used for some historical digital hardware

- [Word](/source/Word_(computer_architecture)) – Base memory unit handled by a computer

## References

1. ^ [***a***](#cite_ref-Intel_1974_MCS-40_1-0) [***b***](#cite_ref-Intel_1974_MCS-40_1-1) [***c***](#cite_ref-Intel_1974_MCS-40_1-2) Raphael, Howard A., ed. (November 1974). ["The Functions Of A Computer: Instruction Register And Decoder"](http://bitsavers.trailing-edge.com/components/intel/MCS40/MCS-40_Users_Manual_Nov74.pdf) (PDF). *MCS-40 User's Manual For Logic Designers*. Santa Clara, California, USA: [Intel Corporation](/source/Intel_Corporation). p. viii. [Archived](https://web.archive.org/web/20200303024244/http://bitsavers.trailing-edge.com/components/intel/MCS40/MCS-40_Users_Manual_Nov74.pdf) (PDF) from the original on 2020-03-03. Retrieved 2020-03-03. [...] The characteristic eight [bit](/source/Bit) field is sometimes referred to as a [byte](/source/Byte), a four-bit field can be referred to as a nibble. [...]

1. **[^](#cite_ref-Hall_1980_2-0)** Hall, Douglas V. (1980). *Microprocessors and Digital Systems*. [McGraw-Hill](/source/McGraw-Hill). [ISBN](/source/ISBN_(identifier)) [0-07-025571-7](https://en.wikipedia.org/wiki/Special:BookSources/0-07-025571-7).

1. **[^](#cite_ref-Warren_2013_3-0)** Warren Jr., Henry S. (2013) [2002]. [*Hacker's Delight*](/source/Hacker's_Delight) (2 ed.). [Addison Wesley](/source/Addison_Wesley) – [Pearson Education, Inc.](/source/Pearson_Education%2C_Inc.) [ISBN](/source/ISBN_(identifier)) [978-0-321-84268-8](https://en.wikipedia.org/wiki/Special:BookSources/978-0-321-84268-8). 0-321-84268-5.

1. ^ [***a***](#cite_ref-esr_4-0) [***b***](#cite_ref-esr_4-1) [Raymond, Eric S.](/source/Eric_S._Raymond) (1996). [*The New Hacker's Dictionary*](https://books.google.com/books?id=g80P_4v4QbIC&pg=PA333). [MIT Press](/source/MIT_Press). p. 333. [ISBN](/source/ISBN_(identifier)) [978-0-262-68092-9](https://en.wikipedia.org/wiki/Special:BookSources/978-0-262-68092-9).

1. **[^](#cite_ref-Carr_1959_5-0)** Carr, John W. *Introduction to the use of digital computers: Notes from the Summer Conference Held at the Computation Center of the University of North Carolina, Chapel Hill, N.C., August 17-28, 1959*. Frontier Research on Digital Computers. Vol. 1. [University of North Carolina](/source/University_of_North_Carolina) at Chapel Hill, Computation Center. p. 211. Each of these letters corresponds to one of the integers from zero to fifteen, therefore requiring 4 bits (one "tetrade") in binary representation.

1. **[^](#cite_ref-Speiser_1965_6-0)** [Speiser, Ambrosius Paul](/source/Ambrosius_Paul_Speiser) (1965) [1961]. *Digitale Rechenanlagen – Grundlagen / Schaltungstechnik / Arbeitsweise / Betriebssicherheit* [*Digital computers – Basics / Circuits / Operation / Reliability*] (in German) (2 ed.). [ETH Zürich](/source/ETH_Z%C3%BCrich), Zürich, Switzerland: [Springer-Verlag](/source/Springer-Verlag) / [IBM](/source/IBM). pp. 6, 34, 165, 183, 208, 213, 215. [LCCN](/source/LCCN_(identifier)) [65-14624](https://lccn.loc.gov/65-14624). 0978.

1. **[^](#cite_ref-Puzman_2012_7-0)** Puzman, Josef; Kubin, Boris (2012). [*Public Data Networks: From Separate PDNs to the ISDN*](https://books.google.com/books?id=ZY7qBwAAQBAJ&pg=PA113). [Springer Science+Business Media](/source/Springer_Science%2BBusiness_Media). p. 113. [ISBN](/source/ISBN_(identifier)) [978-1-4471-1737-7](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4471-1737-7).

1. **[^](#cite_ref-Horak_2007_Websters_8-0)** Horak, Ray (2007). [*Webster's New World Telecom Dictionary*](https://books.google.com/books?id=L18YaEomzjMC&pg=PA402). [John Wiley & Sons](/source/John_Wiley_%26_Sons). p. 402. [ISBN](/source/ISBN_(identifier)) [978-0-470-22571-4](https://en.wikipedia.org/wiki/Special:BookSources/978-0-470-22571-4).

1. **[^](#cite_ref-Brewster_1994_9-0)** Brewster, Ronald L. (1994). [*Data Communications and Networks, Vol. III*](https://books.google.com/books?id=7O5EXtN94PIC&pg=PA155). IEE telecommunications series. Vol. 31. [Institution of Electrical Engineers](/source/Institution_of_Electrical_Engineers). p. 155. [ISBN](/source/ISBN_(identifier)) [978-0-85296-804-8](https://en.wikipedia.org/wiki/Special:BookSources/978-0-85296-804-8). A data symbol represents one quartet (4 bits) of binary data.

1. **[^](#cite_ref-Courbis_1989_10-0)** [Courbis, Paul](/source/Paul_Courbis); Lalande, Sébastien (2006-06-27) [1989]. [*Voyage au centre de la HP28c/s*](https://www.courbis.fr/spip.php?article17) (in French) (2 ed.). Paris, France: Editions de la Règle à Calcul. [OCLC](/source/OCLC_(identifier)) [636072913](https://search.worldcat.org/oclc/636072913). [Archived](https://web.archive.org/web/20160806084555/http://www.courbis.fr/Voyage-au-centre-de-la-HP28-c-s,17.html) from the original on 2016-08-06. Retrieved 2015-09-06. [\[1\]](https://www.courbis.fr/Data/Books/Pdfs_72/Voyage28/Voyage28_72x72_001_063.pdf) [\[2\]](https://www.courbis.fr/Data/Books/Pdfs_72/Voyage28/Voyage28_72x72_064_113.pdf) [\[3\]](https://www.courbis.fr/Data/Books/Pdfs_72/Voyage28/Voyage28_72x72_114_163.pdf) [\[4\]](https://www.courbis.fr/Data/Books/Pdfs_72/Voyage28/Voyage28_72x72_164_213.pdf) [\[5\]](https://www.courbis.fr/Data/Books/Pdfs_72/Voyage28/Voyage28_72x72_214_263.pdf) [\[6\]](https://www.courbis.fr/Data/Books/Pdfs_72/Voyage28/Voyage28_72x72_264_285.pdf)

1. **[^](#cite_ref-Intro_CPP_1997_11-0)** Heller, Steve (1997). [*Introduction to C++*](https://books.google.com/books?id=KbiDKrvExnsC&pg=PA27). [Morgan Kaufmann](/source/Morgan_Kaufmann). p. 27. [ISBN](/source/ISBN_(identifier)) [978-0-12-339099-8](https://en.wikipedia.org/wiki/Special:BookSources/978-0-12-339099-8). Each hex digit (0–f) represents exactly 4 bits.

1. **[^](#cite_ref-Intel_1973_MCS-4_12-0)** ["Terms And Abbreviations"](http://bitsavers.trailing-edge.com/components/intel/MCS4/MCS-4_Assembly_Language_Programming_Manual_Dec73.pdf) (PDF). *MCS-4 Assembly Language Programming Manual – The INTELLEC 4 Microcomputer System Programming Manual* (Preliminary ed.). Santa Clara, California, USA: [Intel Corporation](/source/Intel_Corporation). December 1973. pp. v, 2–6. MCS-030-1273-1. [Archived](https://web.archive.org/web/20200301235541/http://bitsavers.trailing-edge.com/components/intel/MCS4/MCS-4_Assembly_Language_Programming_Manual_Dec73.pdf) (PDF) from the original on 2020-03-01. Retrieved 2020-03-02. [...] [Bit](/source/Bit) – The smallest unit of information which can be represented. (A bit may be in one of two states I 0 or 1). [...] [Byte](/source/Byte) – A group of 8 contiguous bits occupying a single memory location. [...] [Character](/source/Character_(computing)) – A group of 4 contiguous bits of data. [...] (NB. This [Intel 4004](/source/Intel_4004) manual uses the term *character* referring to *4-bit* rather than 8-bit *data* entities. Intel switched to use the more common term *nibble* for 4-bit entities in their documentation for the succeeding processor [4040](/source/Intel_4040) in 1974 already.)

1. **[^](#cite_ref-13)** Hollandbeck, Andy (2022-08-04). ["In a Word: Common Words You Didn't Know Were Also Units of Measure"](https://www.saturdayeveningpost.com/2022/08/in-a-word-common-words-you-didnt-know-were-also-units-of-measure/). *The Saturday Evening Post*. Retrieved 2025-01-04.

1. **[^](#cite_ref-Lechner_1982_Beneath_Apple_DOS_14-0)** Worth, Don D.; Lechner, Pieter M. (May 1982) [1981]. [*Beneath Apple DOS*](https://archive.org/stream/Beneath_Apple_DOS_OCR#page/n24/mode/1up) (4th printing, 1st ed.). Reseda, California, USA: [Quality Software](/source/Quality_Software). Retrieved 2017-03-21. [\[7\]](http://asciiexpress.net/files/docs/Beneath%20Apple%20DOS%20OCR.pdf) [\[8\]](https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Books/Beneath%20Apple%20DOS.pdf) [\[9\]](http://fd.fabiensanglard.net/prince_of_persia/Beneath%20Apple%20DOS.pdf) [Archived](https://web.archive.org/web/20160309202219/http://fd.fabiensanglard.net/prince_of_persia/Beneath%20Apple%20DOS.pdf) 9 March 2016 at the [Wayback Machine](/source/Wayback_Machine)

1. **[^](#cite_ref-Lechner_1985_Beneath_Apple_ProDOS_15-0)** Worth, Don D.; Lechner, Pieter M. (March 1985) [1984]. [*Beneath Apple ProDOS – For Users of Apple II Plus, Apple IIe and Apple IIc Computers*](http://www.apple-iigs.info/doc/fichiers/beneathprodos.pdf) (PDF) (2nd printing, 1st ed.). Chatsworth, California, USA: [Quality Software](/source/Quality_Software). [ISBN](/source/ISBN_(identifier)) [0-912985-05-4](https://en.wikipedia.org/wiki/Special:BookSources/0-912985-05-4). [LCCN](/source/LCCN_(identifier)) [84-61383](https://lccn.loc.gov/84-61383). [Archived](https://web.archive.org/web/20170321014045/http://www.apple-iigs.info/doc/fichiers/beneathprodos.pdf) (PDF) from the original on 2017-03-21. Retrieved 2017-03-21. [\[10\]](https://archive.org/details/A2_BENEATH_APPLE_PRODOS_1_1984)

1. **[^](#cite_ref-CP_1989_CopyII_16-0)** [*Copy II Plus Version 9 – ProDOS/DOS Utilities – Data Recovery, File Management, Protected Software Backup*](http://cps.applearchives.com/copy_ii_plus_9x_manual.pdf) (PDF). 9.0. [Central Point Software, Inc.](/source/Central_Point_Software%2C_Inc.) 1989-10-31 [1982]. Retrieved 2017-03-21.{{[cite book](https://en.wikipedia.org/wiki/Template:Cite_book)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service))

1. **[^](#cite_ref-Apple_1982_IWM_17-0)** [Apple Computer, Inc.](/source/Apple_Computer%2C_Inc.) (February 1982) [1978]. [*Integrated Woz Machine (IWM) Specification*](http://www.brutaldeluxe.fr/documentation/iwm/apple2_IWM_Spec_Rev19_1982.pdf) (PDF) (19 ed.). DigiBarn Computer Museum. [Archived](https://web.archive.org/web/20160806095036/http://www.brutaldeluxe.fr/documentation/iwm/apple2_IWM_Spec_Rev19_1982.pdf) (PDF) from the original on 2016-08-06. Retrieved 2016-08-06.

1. **[^](#cite_ref-Baccala_1997_18-0)** Baccala, Brent (April 1997). ["Binary arithmetic"](http://www.freesoft.org/CIE/Topics/19.htm). *Connected: An Internet Encyclopedia* (3rd ed.). [Archived](https://web.archive.org/web/20160806094514/http://www.freesoft.org/CIE/Topics/19.htm) from the original on 2016-08-06. Retrieved 2015-07-20.

## External links

- ["Apple Assembly Line"](http://www.txbobsc.com/aal/1981/aal8105.html). May 1981.

v t e Units of information Platform-independent units bit hextet octet Platform-dependent units nibble byte syllable word Metric bit units kilobit megabit Metric byte units kilobyte megabyte gigabyte

---
Adapted from the Wikipedia article [Nibble](https://en.wikipedia.org/wiki/Nibble) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Nibble?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.