SARA is the Amsterdam Universities' Computing Centre of the University of Amsterdam (UvA), the Free University (VU) and the Centre for Mathematics (MC). SARA is a foundation maintaining computing facilities for its founders. SARA's computing services include:
-General service on two Cyber 170-750 mainframes,
-Supercomputer service on a Cyber 205,
-IBM 4341 service for the universities' administrations,
-UNIX service on a PDP 11/70.
About TEX
TEX (1), devised by the wellknown D.E. Knuth, is the "state of the art" program for typesetting of text, especially for mathematic texts larded with formula's.
At many sites TEX output is produced off-line using a phototypesetter. The process of running TEX and getting your output from a phototypesetter is a process taking often a few days(!).
TEX is not an easy to use wordprocessor, TEX commands are quite errorprone, so "debugging" a TEX document is a rather tedious process, if you have to wait for days to get output with some typing errors.
Also, phototypesetter output is quite expensive. Phototypesetters use special lightsensitive paper, which has to be developed etc. Clearly, some way of previewing TEX output is necessary, a quick, simple and cheap way to check results directly after running TEX, before making the final high quality output.
Of course other quality demands are made when considering preview compared to the high-quality output of a phototypesetter. For preview the main interest is speed, not high quality. Style variations like italic, bold, slanted, slanted bold etc. are to be reproduced.
(1) TEX and METAFONT, New directions in Typesetting
Donald E. Knuth
Digital Press, Massachusetts
About TEX-output
TEX produces a DeVice Independent (DVI-)file rather than driving an output-device directly. This DVI-file is interpreted by a program running on a dedicated machine. This program, in turn, controls the phototypesetter to produce the printquality text.
At SARA the DVI-file is transported from the mainframe to the phototypesetter using a magnetic tape and so processed off-line.
About the DVI-file
TEX knows of each character within each font (the fonts actually depend on the phototypesetter used) the size of the "box" in which that character fits. Within a word characters are joined, within a line words are joined using an elastic "glue" (spacing).
The positions computed and other information is stored in the DVI-file in the form of commands, together with the ASCII text itself. The DVI-file is a "stream" of 8-bit bytes (it is a binary file). The format of the commands is very much like machine language, consisting of an opcode and, if necessary, parameters. Hardcopy output is produced by interpreting these commands and driving an output-device, e.g. a phototypesetter.
TEX Preview
TEX Preview is a Macintosh application which reads a DVI-file from TEX and displays the subsequent pages on the Macintosh screen.
With TEX Preview you can:
-Check results directly after running TEX,
-See what an entire page looks like, its general appearance,
-View a small part of a page, for example to view a single formula, using the "Zoom" feature,
-Print pages with the ImageWriter,
-Check style variations like italic, bold, slanted, slanted bold etc. and math symbols.
TEX Preview is controlled by pressing buttons and setting options in the standard Macintosh way. The operation of TEX Preview is quite obvious if you are familiar with other Macintosh applications. For a really moving demonstration (sic!) choose the "About TeX Preview..." item in the Apple menu.
