In
typography
Typography is the art and technique of arranging type to make written language legible, readable and appealing when displayed. The arrangement of type involves selecting typefaces, point sizes, line lengths, line-spacing ( leading), ...
and
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, characters per line (CPL) or terminal width refers to the maximal number of
monospaced
A monospaced font, also called a fixed-pitch, fixed-width, or non-proportional font, is a font whose letters and characters each occupy the same amount of horizontal space. This contrasts with variable-width fonts, where the letters and spaci ...
characters that may appear on a single
line. It is similar to
line length
In typography, line length is the width of a block of typeset text, usually measured in units of length like inches or points or in characters per line (in which case it is a measure). A block of text or paragraph has a maximum line length that ...
in
typesetting
Typesetting is the composition of text by means of arranging physical ''type'' (or ''sort'') in mechanical systems or '' glyphs'' in digital systems representing '' characters'' (letters and other symbols).Dictionary.com Unabridged. Random ...
.
History
![Particolare Olivetti Lettera 22](https://upload.wikimedia.org/wikipedia/commons/3/39/Particolare_Olivetti_Lettera_22.JPG)
The limit of the line length in 70–80 characters may well have originated from various technical limitations of various equipment. The American
teletypewriter
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initia ...
s could type only 72 CPL, while the British ones even less, 70 CPL. In the era of
typewriter
A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectivel ...
s, most designs of the typewriter carriage were limited to 80–90 CPL. Standard paper sizes, such as the international standard
A4, also impose limitations on line length: using the US standard
Letter paper size (8.5×11"), it is only possible to print a maximum of 85 or 102 characters (with the font size either 10 or 12
characters per inch) without margins on the typewriter. With various margins – usually from for each side, but there is no strict standard – these numbers may shrink to 55–78 CPL.
![Typometer 3](https://upload.wikimedia.org/wikipedia/commons/0/00/Typometer_3.jpg)
In computer technology, a line of an IBM
punched card
A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
consisted of 80 characters. Widespread computer terminals such as DEC's
VT52
The VT50 was a CRT-based computer terminal introduced by Digital Equipment Corporation (DEC) in July 1974. It provided a display with 12 rows and 80 columns of upper-case text, and used an expanded set of control characters and forward-only scro ...
and
VT100
The VT100 is a video terminal, introduced in August 1978 by Digital Equipment Corporation (DEC). It was one of the first terminals to support ANSI escape codes for cursor control and other tasks, and added a number of extended codes for special ...
mostly followed this standard, showing 80 CPL and 24 lines. This line length was carried over into the original 80×25
text mode
Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of ''character cells'', each ...
of the
IBM PC, along with its clones and successors. To this day, virtual terminals most often display 80×24 characters.
The "long" line of 132 CPL comes from mainframes'
line printer
A line printer prints one entire line of text before advancing to another line. Most early line printers were
impact printers.
Line printers are mostly associated with unit record equipment and the early days of digital computing, but the ...
s. However, some printers or printing terminals could print as many as 216 CPL, given certain extra-wide paper sizes and/or extra-narrow font sizes.
In modern computing
With the advent of desktop computing and publishing, and technologies such as
TrueType
TrueType is an outline font standard developed by Apple in the late 1980s as a competitor to Adobe's Type 1 fonts used in PostScript. It has become the most common format for fonts on the classic Mac OS, macOS, and Microsoft Windows operating ...
used in
word processing
A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...
and
web browsing
Web navigation refers to the process of navigating a Computer network, network of web resource, information resources in the International World Wide Web Conference, World Wide Web, which is organized as hypertext or hypermedia. The user interface ...
, a uniform CPL has been made mostly obsolete.
HTML
The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaSc ...
(and some other modern text presentation formats) uses dynamic
word wrap
Line breaking, also known as word wrapping, is breaking a section of text into lines so that it will fit into the available width of a page, window or other display area. In text display, line wrap is continuing on a new line when a line is ful ...
ping which is more flexible than characters per line restriction and may produce a text block with non-rectangular shape, just like in paper
typesetting
Typesetting is the composition of text by means of arranging physical ''type'' (or ''sort'') in mechanical systems or '' glyphs'' in digital systems representing '' characters'' (letters and other symbols).Dictionary.com Unabridged. Random ...
.
Many
plain text
In computing, plain text is a loose term for data (e.g. file contents) that represent only characters of readable material but not its graphical representation nor other objects (floating-point numbers, images, etc.). It may also include a limit ...
documents still conform to 72 CPL out of tradition (e.g., ).
In programming
Many
style guides
A style guide or manual of style is a set of standards for the writing, formatting, and design of documents. It is often called a style sheet, although that term also has multiple other meanings. The standards can be applied either for gener ...
for
computer programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...
define the maximum or desirable number of characters in a line of
source code
In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the w ...
:
See also
*
IBM 80-column punched card format
*
Apple 80-Column Text Card The Apple 80-Column Text Card was an expansion card for the Apple IIe computer to give it the option of displaying 80 columns of text instead of the usual 40 columns. Two models were available; the cheaper 80-column card had just enough extra RAM t ...
*
Column (typography)
In typography, a column is one or more vertical blocks of content positioned on a page, separated by gutters (vertical whitespace) or rules (thin lines, in this case vertical). Columns are most commonly used to break up large bodies of text that ...
*
Line length
In typography, line length is the width of a block of typeset text, usually measured in units of length like inches or points or in characters per line (in which case it is a measure). A block of text or paragraph has a maximum line length that ...
(the equivalent concept for non-monospaced text)
References
{{reflist, 30em
Text user interface
Typography
Typesetting
Wikipedia articles with ASCII art