Xref: utzoo comp.text:7799 comp.text.tex:4533 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!mcsun!ukc!dcl-cs!aber-cs!athene!pcg From: pcg@cs.aber.ac.uk (Piercarlo Grandi) Newsgroups: comp.text,comp.text.tex Subject: Re: Using TeX for the UNIX man pages Message-ID: Date: 25 Dec 90 22:46:17 GMT References: <657@silence.princeton.nj.us> <1990Dec4.130922.6961@bellcore.bellcore.com> <1990Dec4.133655.15047@noao.edu> <1990Dec4.211419.2599@robobar.co.uk> <4344@undis.cs.chalmers.se> < Sender: pcg@aber-cs.UUCP Organization: Coleg Prifysgol Cymru Lines: 73 Nntp-Posting-Host: teachk In-reply-to: jeffrey@cs.chalmers.se's message of 20 Dec 90 13:05:02 GMT On 20 Dec 90 13:05:02 GMT, jeffrey@cs.chalmers.se (Alan Jeffrey) said: [ ... on how to make TeX produce output for a fixed pitch device ... ] jeffrey> Certainly, in order to produce perfect output you'd have to jeffrey> produce a device-dependent .dvi file, No, the device file would still be device independent -- the contents would be tailored for a specific device. Notice that DVI files are already now tailored for a specific device (device dependent in your sense) in two ways: the first is that each DVI file is for a device with a specific set of fonts, and the second is that it is for a device with 1/65k resolution. If your actual output device does not have that set of fonts or that resolution the DVI driver has to make some mapping. To assist in the mapping betwen the idealized device presumed by current DVI files and the actual one is the reason why virtual fonts exist and a standard rounding algorithm is being defined. There is another alternative, and it is to produce a DVI file that is tailored not for an idealized device but for an actual device, so that no mapping is required for that actual device. Since the DVI output would still be device independent in format, one could take the DVI file tailored for a specific device and map it onto another device, and this would be more or less successful depending on how similar the devices were. The problem with the 1/65K resolution, CM fonts based idealized device for which DVI files are currently tailored is that it is hard to map onto lower resolution actual devices, especially those that have fixed pitch characters and motions, like a CRT or a line printer. jeffrey> The problem is that TeX is designed for producing books on jeffrey> 1270dpi and up printers, and it's output is rather compromised jeffrey> for anything else. TeX views laser printers as proofing jeffrey> devices, and doesn't take much effort about precise spacing at jeffrey> low resolutions. This is the *goal*, but the actual TeX mechanism is far more general. The virtual device for which by default TeX output is currently tailored does indeed map most easily onto a high resolution typesetter, but I think that it is possible to describe to TeX different output devices. Note that all this is already true with ditroff, where you have a something (DESC) like a TFM that gives you the parameters of the intended output device. A ditroff output file is device independent, in that it can be printed on any device, but tailored (optimized) for a specific device. TeX is used as the old C/A/T troff is being used, as currently TeX DVI drivers do what psroff does, mapping a virtual (C/A/Ts are no longer manufactured :->) device onto real ones. The only advantage of the CM based, 1/65k virtual device assumed by TeX is that it is richer than the old C/A/T one. jeffrey> If you want device dependent .dvi files though, it's not that hard to jeffrey> get them by a metafont hack that produces letter-widths and kerns at jeffrey> multiples of the device pixel width (see how the gray font works for jeffrey> details). Inter-word spacing would still be at arbitrary precision, jeffrey> but inter-word jumps aren't nearly as noticable as inter-letter jumps, jeffrey> as long as you're printing on a variable-pitch printer. I am not a TeXnician, but I think this is not true. You can do fixed pitch printing with TeX, both as to fixed width letters and interword and interline spacing, e.g. for code listings. I reckon that it is time for TeX to realize its potential as a ditroff, not as a troff tied to one specific virtual output device to be mapped more or less neatly onto actual devices. -- Piercarlo Grandi | ARPA: pcg%uk.ac.aber.cs@nsfnet-relay.ac.uk Dept of CS, UCW Aberystwyth | UUCP: ...!mcsun!ukc!aber-cs!pcg Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk