PostScript

language, text, graphics A page description language based

on work originally done by John Gaffney at Evans and

Sutherland in 1976, evolving through "JaM" ("John and Martin",

Martin Newell) at XEROX PARC, and finally implemented in its

current form by John Warnock et al. after he and Chuck Geschke

founded Adobe Systems, Inc. in 1982.

PostScript is an interpreted, stack-based language (like

FORTH). It was used as a page description language by the

Apple LaserWriter, and now many laser printers and

on-screen graphics systems. Its primary application is to

describe the appearance of text, graphical shapes, and sampled

images on printed or displayed pages.

A program in PostScript can communicate a document description

from a composition system to a printing system in a

device-independent way.

PostScript is an unusually powerful printer language because

it is a full programming language, rather than a series of

low-level escape sequences. (In this it parallels Emacs,

which exploited a similar insight about editing tasks). It is

also noteworthy for implementing on-the fly rasterisation,

from Bezier curve descriptions, of high-quality fonts at

low (e.g. 300 dpi) resolution (it was formerly believed that

hand-tuned bitmap fonts were required for this task).

PostScript's combination of technical merits and widespread

availability made it the language of choice for graphical

output until PDF appeared.

The Postscript point, 1/72 inch, is slightly different from

other point units.

An introduction.

["PostScript Language Reference Manual" ("The Red Book"),

Adobe Systems, A-W 1985].

[Jargon File]

(2002-03-11)