Path: utzoo!attcan!uunet!microsoft!georgem
From: georgem@microsoft.UUCP (George Moore)
Newsgroups: comp.sys.mac
Subject: Re: Creating Postscript file
Keywords: Postscript, Laserwriter
Message-ID: <7391@microsoft.UUCP>
Date: 16 Aug 89 01:58:10 GMT
References: <15022@dartvax.Dartmouth.EDU>
Reply-To: georgem@microsoft.UUCP (George Moore)
Organization: Microsoft Corp., Redmond WA
Lines: 35

In article  Chang.P.Woo@dartmouth.edu (Chang P. Woo) writes:
>
>Does that mean that I should send the Postscript file with headers?
>[...] Since all laserwriters available for use around here are Apple's
>Laserwriters, I don't know what to do exactly.

Yes.  If you are going to be saving the PostScript from the Mac for later
printing on a non-Appletalk (and non-initialized) LaserWriter, you must
save the LaserPrep header.

When the Print Manager in your Mac starts to generate the PostScript, it 
interrogates the target LaserWriter's PostScript interpreter to see if
the LaserPrep has been downloaded already, and if it has, if it is the 
right version.

This LaserPrep header contains PostScript subroutine "shortcuts" for the 
Mac to use while printing, in order to save download and interpretation 
time.  Like defining "bd" to "bind def" and things like that.  Makes for
very compact, if human unfriendly, output.  BTW, my hat is off to the
Apple engineer(s) who wrote LaserPrep -- several hundred lines of elegant
PostScript code with beautiful stack management/manipulation.

ANYWAY, when your Mac produces this PostScript dump, it assumes the
LaserPrep has already been downloaded.  If not, your dump will die if fed
to a non-initialized PostScript device.  The thing to remember is:

     Dump with header?	  Previously initialized printer?	Output?
	   Yes			        No			 Yes
	   No			        Yes			 Yes
	   Yes			        Yes			 No
	   No			        No			 No

Just think of it as an XOR operation.   :-)

	-George Moore	(georgem@microsoft.COM)