A ten-rod abacus would be able
to represent a ten-digit decimal number, or a maxmium value of
9,999,999,999. If we wished to represent a larger number on this abacus, we
would be unable to, unless additional rods could be added to it.
In digital, electronic computer design, it is common to
design the system for a common "bit width:" a maximum number of bits
allocated to represent numerical quantities. Early digital computers handled
bits in groups of four or eight. More modern systems handle numbers in
clusters of 32 bits or more. To more conveniently express the "bit width" of
such clusters in a digital computer, specific labels were applied to the
more common groupings.
Eight bits, grouped together to form a single binary
quantity, is known as a *byte*. Four bits, grouped together as one
binary number, is known by the humorous title of *nibble*, often
spelled as *nybble*.
A multitude of terms have followed byte and nibble for
labeling specfiic groupings of binary bits. Most of the terms shown here are
informal, and have not been made "authoritative" by any standards group or
other sanctioning body. However, their inclusion into this chapter is
warranted by their occasional appearance in technical literature, as well as
the levity they add to an otherwise dry subject:
Bit: A single, bivalent unit of binary notation.
Equivalent to a decimal "digit."
Crumb, Tydbit, or Tayste: Two bits.
Nibble, or Nybble: Four bits.
Nickle: Five bits.
Byte: Eight bits.
Deckle: Ten bits.
Playte: Sixteen bits.
Dynner: Thirty-two bits.
Word: (system dependent).
The most ambiguous term by far is *word*, referring to
the standard bit-grouping within a particular digital system. For a computer
system using a 32 bit-wide "data path," a "word" would mean 32 bits. If the
system used 16 bits as the standard grouping for binary quantities, a "word"
would mean 16 bits. The terms *playte* and *dynner*, by contrast,
always refer to 16 and 32 bits, respectively, regardless of the system
context in which they are used.
Context dependence is likewise true for derivative terms of *
word*, such as *double word* and *longword* (both meaning twice
the standard bit-width), *half-word* (half the standard bit-width), and *
quad* (meaning four times the standard bit-width). One humorous addition
to this somewhat boring collection of *word*-derivatives is the term *
chawmp*, which means the same as *half-word*. For example, a *
chawmp* would be 16 bits in the context of a 32-bit digital system, and
18 bits in the context of a 36-bit system. Also, the term *gawble* is
sometimes synonymous with *word*.
Definitions for bit grouping terms were taken from Eric S.
Raymond's "Jargon Lexicon," an indexed collection of terms -- both common and
obscure -- germane to the world of computer programming. |