nybble

A nybble, sometimes spelled nibble, is a unit of information that consists of four binary digits (bits). It is half of a byte, which is typically eight bits in modern architectures. A nybble can represent 16 distinct values, from 0 to 15.

Etymology and spelling: The term nybble is an alternative spelling of nibble that has appeared in older literature to emphasize its status as half a byte. The exact origin of the spelling variation is not definitively documented, and nibble is the more common form in contemporary writing.

Relation to bytes and hex: In hexadecimal notation, one hex digit corresponds to a single nybble. Two nybbles make up one byte, and most data representations show bytes as two hex digits. Nybbles are convenient for packing digits in four-bit groups, such as in some BCD (binary coded decimal) schemes or in color code systems with four bits per channel.

Usage and context: Nybbles are widely used as a conceptual and practical unit in digital design, debugging, and documentation. They arise in discussions of memory addresses, data buses, and instruction encoding, especially in contexts where four-bit operations or representations are relevant. Historically, some early or specialized processors operated on 4-bit words, making nybbles a natural data unit; in modern general-purpose computing, the nybble is typically an abstract or convenient fraction of a byte rather than a native word size.

See also: nibble; byte; hexadecimal; BCD.