Organization: UAB Photo & Graphics
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Date:         Wed, 12 Aug 1992 08:09:37 CDT
From:         Jeff Bone <JBONE@DOPIG.UAB.EDU>
Subject:      PAP Error Defined...(Awfully Arogant huh?)
X-To:         PAGEMAKR%INDYCMS.bitnet@UABDPO.DPO.UAB.EDU

Leonard Chan writes...

> I think what PAP you guys talking about is the Printer Access Protocol from
> Apple. When I look at the problems, I find that people have problems on
 printing
> from system 6.0.x but printing from 7.x seems ok. May be you can try reset
 your
> RIP (reinitialize?) and print from 6.0.x again. Or upgrade your system to 7.x
> may also solve your problem.

PAP - Printer Access Protocol allows Macintosh users to access printers
      or print queues on the AppleTalk network.

      In other words you have tons of little packets of information flying
      around your AppleTalk (or EtherTalk) network some of which are
      pieces of information that contain actual data files if you are
      running System 7 file-sharing, AppleShare, or Netware; some contain
      advertisements for servers and printers (known as NBP
      advertisements) that let your Macintosh "see" the device, and then
      there are PAPs which are packets of information destined for
      a specific printer that were created by someone's Macintosh when
      they said "print."

      Since it is not efficeint to send a large PostScript print file in
      one large packet, it is broken up into a series of little "PAP"
      packets.  If one of these little packets gets mis-transmitted along
      the wire for whatever reason (literally hundreds of reasons) it
      generates an error known as a PAP error.  Obviously you can see that
      if one little packet got lost along the way the PostScript
      information would be corrupt and your printer will "flush" it.

      Transparent-to-the-user attempts are usually made by the printer and
      computer to re-transmitt this missing packet, but if this
      fails the print job fails.

      Since I stated that mis-transmissions can occur for hundreds of
      reasons I'll only note what I think, IMHO, are the most common
      reasons:

      (1) Bad transmission media - AppleTalk/EtherTalk connectors not
          tight, broken, or poorly placed (like parallel with AC lines).
      (2) Hiccup of the Mac at printing - from packages like PM that re-
          quire large amounts of transmitted data, any hiccup of the Mac
          due to your screen saver, SAM, etc. will cause bad packets
      (3) Corrupt printer driver - which _CAN_ occur even in the best
          maintained systems.  Remedy by reloading the driver.

Hope this helps, sorry for not piping in earlier.  I'm sure others have
experienced this too, maybe they have some other thoughts.



----------------------------------------------------------------
** Jeff Bone                                <jbone@dopig.uab.edu>
** Coordinator for Electronic Imaging       AppleLink: jbone
** Photography and Instructional Graphics   205.934.4396 voice
** University of Alabama at Birmingham      205.934.3749 fax
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