Nibble
In computing, a nibble, also spelled nybble[1] to match byte,[2] is a unit of information consisting of four bits,[3] equivalent to one half of a byte or octet (data units of eight-bit length).[4][5] The unit is alternatively called a nybble, nybl, half-byte or tetrad.[6][7] In computer networking and telecommunications, the unit is also sometimes called a semi-octet,[8] quadbit,[9] or quartet.[10][11]
A nibble uses four digits in binary positional notation (base 2) to encode one of sixteen () possible values, representing the same amount of information stored by two digits in the quaternary numeral system (base 4) or just a single hexadecimal ("hex")[12] digit (base 16). That functional equivalence allows nibbles to typically be represented by a single hex digit, and likewise, byte values by a pair of hex digits.[12]
Four-bit computers use nibble-sized data for storage and operations, in the form of the word unit. Such computers were used in early microprocessors, pocket calculators and pocket computers, and continue to be used in some microcontrollers. In this context, 4-bit groups were sometimes also called characters[13] or digits[14] rather than nibbles.[3]
History
The term nibble originates from its representing half a byte, with byte a homophone of the English word bite.[2] David B. Benson may have coined its use to describe four-bit values as a joke while working as a professor at Washington State University in 1958.[15]
Part of a byte
Packed nibbles can also describe binary numbers. When converting from bytes to nibbles,the two halves are often referred to as the low (right) and high (left) nibbles rather than the more formal labels of least- and most-significant bits.[16] For example, in the binary representation for the natural number 97, , the high nibble is () and the low nibble is (). That same number expressed in hexadecimal is simply , with each nibble now reduced to a single digit that nonetheless represents the same value ().
Value representation
A nibble-sized value can be represented in different numeric bases:
See also
- Binary number – Number expressed in the base-2 numeral system
- Syllable
- Word – Base memory unit handled by a computer
References
- ↑ Sander-Cederlof, Bob (May 1981). "Commented Listing of DOS 3.2.1, $B800-BCFF". Apple Assembly Line (Richardson, Texas: S-C Software) 1 (8). https://www.txbobsc.com/aal/1981/aal8105.html#a5. Retrieved 2026-06-11. "PRE.NYBBLE and POST.NYBBLE convert between memory format and disk format. […] PRE.NYBBLE converts the 256-byte buffer to 410 bytes of 5-bits each, then […] POST.NYBBLE converts the 410 5-bit values back to 256 8-bit bytes.".
- ↑ 2.0 2.1 Raymond, Eric S., ed (1991-09-21). The New Hacker's Dictionary (1st ed.). Cambridge, Massachusetts: MIT Press. p. 265. ISBN 0-262-18145-2. OCLC 1036797040. https://archive.org/details/newhackersdictio00raym/page/265/mode/1up. Retrieved 2026-05-21. "nybble /nib´l/ (alt. nibble) [from v. ´nibble´ by analogy with ´bite´ ⇒ ´byte´] n. Four bits; one hex digit; a half-byte. […]"
- ↑ 3.0 3.1 Raphael, Howard A., ed (November 1974). "The Functions Of A Computer: Instruction Register And Decoder". MCS-40 User's Manual For Logic Designers. Santa Clara, California: Intel Corp.. p. viii. https://bitsavers.trailing-edge.com/components/intel/MCS40/MCS-40_Users_Manual_Nov74.pdf. Retrieved 2020-03-03. "The characteristic eight bit field is sometimes referred to as a byte, a four-bit field can be referred to as a nibble."
- ↑ Hall, Douglas V. (1980). Microprocessors and Digital Systems (1st ed.). New York City: Gregg Division, McGraw-Hill, Inc.. p. 76. ISBN 0-07-025571-7. OCLC 1285744331. https://archive.org/details/microprocessorsd0000hall/page/76/mode/1up. Retrieved 2026-05-21. "An eight-bit binary word is often called a byte, and a four-bit binary word is called a nibble."
- ↑ Warren, Henry S., Jr. (July 2002). "Chapter 1–1: Notation". Hacker's Delight (1st ed.). Boston: Addison-Wesley. p. 1. ISBN 0-201-91465-4. OCLC 49559016. https://www.google.com/books?id=iBNKMspIlqEC&gbpv=1. Retrieved 2026-05-22. "The terms "bits," "nibbles," "bytes," "halfwords," "words," and "doublewords" refer to lengths of 1, 4, 8, 16, 32, and 64 bits, respectively."
- ↑ "Introduction to the Use of Digital Computers, Programming and Artificial Intelligence". 1. 1959. 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."
- ↑ Speiser, Ambrosius Paul (1965). written at ETH Zurich (in de). Digitale Rechenanlagen: Grundlagen / Schaltungstechnik / Arbeitsweise Betriebssicherheit (2nd ed.). Berlin/Heidelberg: Springer-Verlag. pp. 6–9,164–165,183,208–212. doi:10.1007/978-3-642-92953-3. ISBN 978-3-642-92954-0. "Es gibt 10 verschiedene Dezimalziffern. Mit 4 Dualstellen lassen sich 24 = 16 Kombinationen bilden, also miissen 4 Dualstellen geniigen, um eine Dezimale zu verkörpern. Eine solche Vierergruppe wird als Tetrade bezeichnet."
- ↑ Pužman, Josef; Kubín, Boris (2012-12-06). Public Data Networks: From Separate PDNs to the ISDN (2nd ed.). London: Springer-Verlag. p. 112–114. doi:10.1007/978-1-4471-1737-7. ISBN 978-1-4471-1737-7. https://books.google.com/books?id=ZY7qBwAAQBAJ&pg=PA113. Retrieved 2026-05-22. "[…] the X.25 packet format is octet-oriented (it is an integer multiple of 8-tuples of bits), though in some cases only semi-octets (4 bits) provide comprehensive information."
- ↑ Horak, Ray (2007-11-28) (PDF). Webster's New World Telecom Dictionary. Indianapolis: Wiley Publishing, Inc.. p. 402. ISBN 978-0-471-77457-0. https://kolegite.com/EE_library/books_and_lectures/Комуникационна%20техника/Websters%20New%20World%20Telecom%20Dictionary-2007.pdf. "quadbit 1. A set of four bits."
- ↑ Brewster, Ronald L., ed (1994). Data communications and networks 3. IEE Telecommunications Series. 31 (3rd ed.). London: Institution of Electrical Engineers. p. 155. ISBN 978-0-85296-804-8. OCLC 1391398597. https://www.google.com/books?id=7O5EXtN94PIC&gbpv=1&pg=PA155. "A data symbol represents one quartet (4 bits) of binary data; 16 symbols are thus required to convey data."
- ↑ Courbis, Paul; Lalande, Sébastien (2006-06-27). "Chapitre V - L'accès au langage-machine: comment entrer un programme-machine ou, plus généralement, un objet quelconque (ASS / LASS)" (in fr). Voyage au centre de la HP28c/s (2nd ed.). Paris: La Règle à Calcul. pp. 63,105. OCLC 636072913. https://www.courbis.fr/Data/Books/DeliverPdf.cgi?Pdfs_72/Voyage28/Voyage28_72x72_064_113.pdf. Retrieved 2015-09-06. "Comme un caractère de la chaîne LM représente un quartet et que l'on veut créer une chaîne comme résultat on va coder 2 quartets par 2 quartets (1 caractêre ASCll=2 quartets=1 octet)."
- ↑ 12.0 12.1 Heller, Steve (1997-04-24). Introduction to C++ (1st ed.). Morgan Kaufmann. pp. 25–27. ISBN 978-0-12-339099-8. https://www.google.com/books?id=KbiDKrvExnsC&gbpv=1&pg=PA25. "As a rule, the term hexadecimal is abbreviated to hex. Since there are 16 possible combinations of 4 bits (2×2×2×2), hexadecimal notation allows four bits of a binary number to be represented by one hex digit. […] For this reason, binary is almost never used. Instead, we use hex as a shortcut to eliminate the necessity of reading, writing and remembering long strings of bits."
- ↑ "Terms And Abbreviations". MCS-4™ Assembly Language Programming Manual (Preliminary ed.). Santa Clara, California: Intel Corp.. December 1973. pp. v, ((2–6)). https://bitsavers.trailing-edge.com/components/intel/MCS4/MCS-4_Assembly_Language_Programming_Manual_Dec73.pdf. Retrieved 2020-03-02. "Character – A group of 4 contiguous bits of data." (N.B. This Intel 4004 manual uses the term character referring to 4-bit rather than 8-bit data entities. By 1974, Intel had already switched to use the more common term nibble for 4-bit entities in their documentation for the succeeding 4040 processor.)
- ↑ COP400 Microcontroller Family COPS Family User's Guide. National semiconductor. p. 9.10. https://www.datasheetarchive.com/datasheet/COP400/National-Semiconductor. Retrieved 23 June 2025.
- ↑ Hollandbeck, Andy (2022-08-04). "In a Word: Common Words You Didn’t Know Were Also Units of Measure". The Saturday Evening Post (Indianapolis). https://www.saturdayeveningpost.com/2022/08/in-a-word-common-words-you-didnt-know-were-also-units-of-measure/. Retrieved 2025-01-04. "[…] As David Benson, a Washington State University professor, remembered it, he had jokingly made a remark in 1958 about "half a byte" (i.e., "half a bite") being a nibble, and the name stuck.".
- ↑ Baccala, Brent, ed (April 1997). "Binary arithmetic". Connected: An Internet Encyclopedia (3rd ed.). https://www.freesoft.org/CIE/Topics/19.htm. Retrieved 2015-07-20. "Memorize the decimal values for the high nibble (they're just the multiples of 16). The low nibble is trivial. Every number between 0 and 255 is the sum of one of the high nibble values and one of the low nibble values.".
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