Last update: Sat Nov 17 16:21:16 2001
Comments, and reports of errata or bugs, are welcome via e-mail to the author, Nelson H. F. Beebe <email@example.com>. In your report, please supply the full document URL, and the title and Last update time stamp recorded near the top of the document.
PostScript and PDF (Portable Document Format) are page description languages developed by Adobe Systems.
PostScript was first released in the Apple LaserWriter printer in the spring of 1984, and has since become the de facto standard for representing page images for display on printers and other output devices. Virtually all document formatting, typesetting, and desktop publishing systems, and many software packages, are capable of producing PostScript or PDF files directly, or through translators from older formats to these languages.
PDF is a close relative of PostScript, but lacks PostScript's generality and programmability. PDF sees increasingly wide use on the World-Wide Web for presentation of page images of complex documents. PDF files are compact, and PDF viewers offer string searching and random access to any page.
PDF viewers, such as Adobe Acrobat Reader (acroread) and Exchange (acroexch), ghostview, gv, and xpdf, and the utilities pdf2ps and pdftops, can convert PDF to PostScript for printing.
Recent PostScript printers (PostScript language Level 3) can also print PDF files directly. We do not yet have any such printers at this site.
Ghostscript is an independent implementation of an interpreter for the PostScript and PDF languages, and has been developed by Aladdin Enterprises, starting in 1986.
Because Ghostscript is usually available in source form, and has been ported to all commercially significant desktop (and larger) computing platforms, it has extended access to PostScript and PDF even further, far beyond the systems commercially supported by Adobe Systems.
Although Adobe's own software is proprietary, the specifications of PostScript, PDF, and the Adobe font formats are all published in readily-available books, and anyone may implement software to interpret such files. That Aladdin Enterprises has done so with Ghostscript demonstrates that this is feasible, and also helps to ensure that Adobe's own software conforms to the published specifications. In languages as complex as PostScript and PDF, discrepancies between theory and practice are inevitable, and the existence of multiple independent implementations helps to reveal such problems, which can be (and are) fixed in later releases.
Because the PostScript and PDF specifications are public, and stable for long periods (there have been only three versions, called language levels, of PostScript in 16 years, all upward compatible), both can be reliably used for archival purposes.
The University of Utah Mathematics Department is a beta-test site for Ghostscript, and consequently, has access to the latest development versions, which are installed on all of its many architectures and systems.
The links in this section are accessible only to local users.