Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!snorkelwacker!bloom-beacon!eru!luth!sunic!maxim!prc
From: prc@erbe.se (Robert Claeson)
Newsgroups: comp.lang.postscript
Subject: Re: Configuring an Apple LaserWriter for 8-bit postscript
Message-ID: <1046@maxim.erbe.se>
Date: 23 Dec 89 11:14:28 GMT
References: <89352.151243HATHAWA@GECRDVM1.BITNET> <17467@rpp386.cactus.org> <17481@rpp386.cactus.org>
Organization: ERBE DATA AB, Jarfalla, Sweden
Lines: 47

In article <17481@rpp386.cactus.org>, woody@rpp386.cactus.org (Woodrow Baker) writes:
> In article <1044@maxim.erbe.se>, prc@erbe.se (Robert Claeson) writes:

> > The client (ie, the application generating the Postscript
> > code) should not rely on anything else than a 7-bit, no-control-chars data
> > flow. All non-ASCII characters and control characters should be sent in
> > backslash-octal form (ie, \014).

> Of course, of course, but tell that to some program written before postscript
> ever came on the scene.  Remember, more programs write output to a Diablo
> printer than postscript printers. If you have 1 printer and it is a postscript
> printer, you need an emulator perhaps, then what are you gonna do?

Adobe's green book recommends that such emulation is done on the host and not
in the printer. The emulator can then easily emit non-printable-ASCII
characters using the octal escape.

> How do you tell a program that needs to get 8 bits of data out, that it needs
> to watch for control characters, and preface them with \?  Sure, go 
> change the source, IF you have it, and IF you don't have to change 4000 files.

You can't, unless the program already emits 7-bit PostScript. I use to use
a back-end that converts all 8-bit characters in the PostScript that the
application emits into the 7-bit octal form.

> But the biggest gotcha of all, is that that funky \xxx comes through the
> communication routines as just that, "\xxx".  The PS input scanner does
> not (at least what I've seen) do a conversion of the xxx sequence to a binary
> number, but passes it on as ASCII.  Representing hex data i.e. binary data
> in a printable ascii form is o.k., but it doubles the size of the file.
> 
> Yes, the info is in the Red book, but my contention is that it is unduly
> restrictive, we live in an 8 bit world, bytes nolonger have 7 bits.

I agree. I'm an 8-bit junkie myself, and at this site, we only use the ISO
8859/1 8-bit character set. Our whatever-to-postscript converter and
PostScript printer driver (still under development) converts everything into
the 7-bit form, and, just as you say, the size of a typical file almost gets
doubled.

BTW, you can't imagine how many UNIX utilities there are that still lives in
a 7-bit world, and this is under one of the later System V UNIX'es (Berkeley
UNIX is, unfortunately, highly unusable for non-ASCII character sets).

-- 
          Robert Claeson      E-mail: rclaeson@erbe.se
	  ERBE DATA AB