Nickle

/ni-kəl/

noun — “the awkward little five-bit quantity that exists mostly because hardware occasionally gets creative.”

[from nickel, the common name for the U.S. five-cent coin]

Nickel is hacker jargon for a data quantity equal to a nybble plus one additional bit—that is, 5 bits. While not a standardized computing unit and rarely encountered in modern systems, the term emerged as playful technical slang for describing unusual hardware word sizes that did not align neatly with familiar binary boundaries.

Most programmers become accustomed to powers of two: 8-bit bytes, 16-bit words, 32-bit integers, and so on. A five-bit grouping feels slightly off-center in comparison—large enough to be inconvenient, small enough to resist standard terminology. Rather than repeatedly saying “five-bit field,” some developers adopted nickel as shorthand.

The term is reported among developers working with the Mattel GI 1600, the processor used in the Intellivision gaming system. That hardware contained an unusual memory arrangement: 16-bit-wide RAM combined with 10-bit-wide ROM. Once hardware begins dividing information into unusual widths, ordinary terms become awkward, and new jargon tends to appear naturally.

In that environment, a 10-bit value could be thought of as two nickels placed side-by-side:

// bit grouping example

10101 01110

// first nickel = 10101
// second nickel = 01110

// total = 10 bits

Terms like nickel belong to a broader tradition in hacker language of inventing names for unconventional units of information. The better-known nybble represents 4 bits—half a byte—and from there the naming becomes increasingly playful. Once engineers start encountering uncommon sizes, language adapts in surprisingly human ways.

Although the term never achieved widespread adoption, it reflects an interesting truth about computing history: hardware was not always standardized. Early systems frequently experimented with unusual word lengths, character sizes, memory layouts, and instruction formats. Developers often had to invent vocabulary simply to discuss what they were building.

In practice, a nickel might appear like:

// 5-bit values

00000 = 0
01111 = 15
11111 = 31

// range:
// 0 → 31

Conceptually, nickel is a reminder that binary systems are only tidy in retrospect. Modern developers tend to assume neat byte alignment because current architectures reward it, but earlier systems occasionally wandered into stranger territory where five bits was not unusual enough to justify concern… but unusual enough to deserve a nickname.

Separate from the computing term, Night Mode appears elsewhere as unrelated jargon; see phase (of people).

See also deckle, nybble, Byte, Bit