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This page explains how to print the PostScript files provided in the present site.
What is PostScript?
PostScript is a page description programming language for high-quality graphics. A PostScript file contains a sequence of PostScript instructions that generate a graphic figure (graphic elements, images and text). People interested in a detailed description of the PostScript language and its instructions may consult the book PostScript Language Reference Manual by Adobe Systems Inc., Addison-Wesely, 1990, or any other book on the subject. Note that although some PostScript instructions may include binary data, all the PostScript files provided in this site are pure text (ASCII) files.
What is a PostScript printer?
In order to be printed on paper (or shown on your computer display) a PostScript file needs to be interpreted, meaning that the individual PostScript instructions (such as "lineto", "moveto", "image", etc.) must be translated into a sequence of device pixels. This task is performed by a software program that is called a PostScript interpreter. Many printers have a built-in PostScript interpreter, that resides inside the printer itself. Such printers, known as PostScript printers, can directly accept PostScript files, interpret them, and print them on the paper. Other printers (usually cheaper ones) do not include a PostScript interpreter; these printers, called non-PostScript printers, cannot directly accept PostScript instructions. In this case, in order to print a PostScript file, you will need a software package that runs on your computer and translates the PostScript file into your printer's own graphic language.
How to print PostScript files if you have a PostScript printer?
Printing PostScript files on a PostScript printer should be rather straightforward for users of Unix-based computers or for Macintosh users. PC users having a PostScript printer connected directly to the main parallel port of their PC may print a PostScript file by opening a DOS window, and inserting the following DOS command:
type filename.ps > prn If your PostScript printer is connected to another port, you should replace "prn" by the corresponding port name (lpt1:, lpt2:, etc. for the parallel ports, com1:, com2:, etc. for the serial ports). If several printers are connected to your PC, make sure that your PostScript printer has been selected as the default printer. (Remark: The above DOS command assumes that your PostScript file is a pure ASCII file, as is the case for all the PostScript files provided in this site. If you need to print a PostScript file from another source that contains some binary information, use instead the DOS command:
copy /b filename.ps lpt1: again, with the appropriate port name.)
PC users whose PostScript printer is connected through a network may need to use a PostScript interpreter (such as Ghostscript) on their own computer; further details are given in the following section.
What to do if you don't have a PostScript printer?
In this case, you will need to use a software package (PostScript interpreter) that runs on your computer and translates the PostScript file into your printer's own graphic language. Obviously, in this case the quality of the printed graphics will not only depend on the printer quality and resolution, but also on your PostScript interpreter and on its proper use (correct use of the parameters, etc.). A PostScript file that was improperly processed (scaled, resampled, screened or halftoned) by the converting software running on your computer, will probably give poor results even when printed on a high-resolution printer. In such cases the printed graphics may show various visible artifacts, including undesired moiré phenomena, visible jaggies or other disturbing irregularities.
One of the most well-known PostScript interpreters is Ghostscript; a separate frontend (graphical interface) to this interpreter exists under the name of Ghostview (or GSview). Ghostscript and Ghostview run on all main computing platforms: PC, Macintosh, as well as Unix-based computers, and they contain a wealth of drivers for a wide range of printer models. Ghostscript and Ghostview can be obtained free of charge from their official web site; full details on their usage can be found in the Ghostscript User Manual.
Further precious information on printing PostScript files (including on network printers and non-PostScript printers) can be found in Jim Land's PostScript site.
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