Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!munnari.oz.au!comp.vuw.ac.nz!canterbury!phys169
From: phys169@csc.canterbury.ac.nz
Newsgroups: comp.lang.postscript
Subject: Re: HP Laserjet III choking on Laser Prep
Message-ID: <1991May15.170843.751@csc.canterbury.ac.nz>
Date: 15 May 91 05:08:43 GMT
References: <1991May15.111938.743@csc.canterbury.ac.nz>
Organization: University of Canterbury, Christchurch, New Zealand
Lines: 24

In article <1991May15.111938.743@csc.canterbury.ac.nz>, I wrote:
> I've had difficulty in getting an HP Laserjet III (with PostScript) to print
> postscript files using the Laser Prep from Apple, which includes a string of
> characters including "1ab3". 

Thanks for the help. The answer was:

there is a loop doing a read 722 times, for 718 characters of data plus 4 line
terminators (presumably Carriage Returns). The local VAX software is sending
Carriage Return+Line Feed pairs, and the other printer, an NEC, plugged into
the same place must simply be ignoring either the CR or the LF. The extra
one character per line causes headaches for the program, since the last 4
data bytes are interpreted as PS code. 

This is the second time control characters have caused problems for me - a Form
Feed was upsetting a Brother printer, but other PostScript printers simply
ignored it. It seems the response to some common control characters varies from
implementation to implementation (I can't find anything about them either in
the printers' hardware manuals or red & blue PostScript books; perhaps I'm
missing something?).

Morale of Story: beware of control codes, and avoid using "read".

Mark Aitchison, Physics, University of Canterbury, New Zealand.