laser-lovers@uw-beaver (07/07/85)
From: Richard Furuta <Furuta@WASHINGTON.arpa>
I am pleased to announce that we've received a TeX device driver for the
Apple LaserWriter. This driver was developed on an Apollo and runs on
Berkeley Unix. It's written in C and is based on a previous screen
previewer for the Sun.
The driver is self-described as a temporary way to get DVI output to
the LaserWriter. In operation, we have noticed that the first few
pages take quite a long time to print (while the fonts are being
loaded) but that things speed up for subsequent pages. Nevertheless,
it's certainly not as fast as using the built-in fonts.
The driver uses the PXL fonts (bitmaps) at the 300 dot per inch
resolution.
This program is named dvi2ps and it was written by Neal Holtz,
holtz%cascade.carleton.cdn%ubc.csnet@csnet-relay. I believe that
Neal is out of town for a couple of weeks and so further fixes, etc.,
will be delayed until his return.
The program can be ftp-ed from Washington in <tex.xfer>dvi2ps.sh.
This is a plain ascii file (no special mode needed for transfer).
Run it through the shell when you get it to extract the files. I
will also post the file directly to fa.laser-lovers.
Here is Neal's description of the driver:
Dvi2ps is program the translates DVI files to PostScript (PostScript is a
trademark of Adobe Systems, Inc). When the output of dvi2ps is preceded by
about 2 pages of PostScript code, TeX output can be printed on PostScript
devices (such as an Apple LaserWriter).
It uses the TeX-compatible set of 300 dpi fonts, and downloads the bitmap
description of each character, once, as it is needed, for every job (i.e.,
resident fonts are not used). While this sounds expensive, it is not too
bad. After the conversion to PostScript is done, and considering "normal
documents" and 9600 baud communication, the first page can take a minute or
so to transmit and print. Thereafter, pages are usually printed faster.
Simple documents of 20 & 30 pages have printed at an overall average of
3.2 pages/minute (it is unlikely that you will ever get substantially
higher than this with the program as it currently stands). More typical
rates will be 2.5 pages/min. Conversion time is extra, of course, but
does not seem to be excessive.
Dvi2ps currently runs on Apollo (AEGIS) and Vax 4.2BSD machines (and shortly
Macintosh XL with MacWorks).
There are many problems:
1. It is not very clever about which fonts and characters to download on
a per-job basis, except that each character is sent only once, just before
it is needed. All character and fonts are then made resident on the printer
until the end of the job. This consumes more memory on the printer (at least
on the Apple LaserWriter) than is necessary, and can limit the size of the
job than can be printed. "Simple" 50 page documents can be printed
with room to spare (I suspect the limit is in the range of 70-100 pages for
these, but we haven't tried any that large yet). On the other hand,
a section out of the LaTeX test files (manual) that uses 30 or more
different fonts, some of them very large, was limited to 30 pages.
Dvi2ps has -from and -to options to extract ranges of pages.
2. The resulting PostScript files are very large (they can easily be 5 times
the size of the DVI file).
3. Character positioning is not calculated in the "official" dvitype manner,
and so there *might* be *VERY* small anomolies. However, care is taken,
and the result is quite acceptable (at least to many untrained eyes).
In fact, positioning is better than some other common processors, and
no anomolies have as yet been noticed.
In summary, it was quite easy to develop and will serve us well until something
better comes along.
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