Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!tektronix!orca!pogo!richk
From: richk@pogo.WV.TEK.COM (Richard G. Knowles)
Newsgroups: comp.lang.postscript
Subject: Re: ^D embedded in PS files
Message-ID: <7207@pogo.WV.TEK.COM>
Date: 3 May 89 22:58:49 GMT
References: <2994@daisy.UUCP> <775@adobe.UUCP> <8751@polya.Stanford.EDU> <98@snll-arpagw.UUCP> <22489@ccicpg.UUCP>
Reply-To: richk@pogo.WV.TEK.COM (Richard G. Knowles)
Organization: Tektronix, Inc., Wilsonville,  OR.
Lines: 41

In article <22489@ccicpg.UUCP> evans@ccicpg.UUCP ( Scott Evans) writes:
>In article <98@snll-arpagw.UUCP>, paolucci@snll-arpagw.UUCP (Sam Paolucci) writes:
>> Thus it appears to me that in a PC world where access to the serial
>> device is easy and transparent, the only option is for the application
>> program to append a ^D to the end of the PostScript output.  This
>> guarantees that the file will be handled properly whether it is
>> redirected to the serial device, or later copied to it.
>> 
>Can we help it if the PC is a "brain-dead" kind of machine and has no
>other way telling when it gets to an "end of file"????
>
>This is purely a kludge to get around a limitation on the PC.  It is
>especially apparent when you see a ^D not only at the end of a Postscript
>file but also at the beginning!!!
>
>The postscript printer that is hooked up to our Unix system does not like the
>^D at the beginning of the file and so we have to filter all the files that
>come from a PC before they can be printed.  


Whoa there.  Even though I hate to defend the PC, your argument for having
to filter the ^D's out of PC produced PS files is misdirected.  The printer
doesn't care one whit about whether a job has a ^D at the start or not.
What is "brain-dead" is your UNIX spooler which is relying on the ^D echo to
decide when a job has finished.  A ^D at the start of a job makes the
spooler think the job has finished even before all it has been sent.  This
is one dependancy that Adobe's Transcript package has with its lpr filters
(and one which I have removed to be able to effectively use both HP-GL and
PS in the same printer through the same spooler).

BTW, a ^D at the beginning of the file is there precisely because it makes
up for those prior jobs that don't end with a ^D and would leave me with a
printer whose state quite likely is not compatible with my job (like not
leaving much VM or having redefined some operators that I use).

-------- Whatever I say is my fault and no one elses! -----------

Richard G. Knowles                        richk@pogo.WV.TEK.COM
Graphics Printing and Imaging                (503) 685-3860
Tektronix, Inc; D/S 63-356
Wilsonville, Or 97070			or just yell "Hey, Rich!"