From owner-freebsd-hackers Sat Apr 8 1:22: 2 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from chmls06.mediaone.net (chmls06.mediaone.net [24.128.1.71]) by hub.freebsd.org (Postfix) with ESMTP id 1881437B535 for ; Sat, 8 Apr 2000 01:21:59 -0700 (PDT) (envelope-from zdenek@mediaone.net) Received: from funex (zdenek.ne.mediaone.net [24.218.127.20]) by chmls06.mediaone.net (8.8.7/8.8.7) with SMTP id EAA11709 for ; Sat, 8 Apr 2000 04:21:57 -0400 (EDT) Message-Id: <200004080821.EAA11709@chmls06.mediaone.net> X-Sender: zdenek@pop.ne.mediaone.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.0 Date: Sat, 08 Apr 2000 05:21:06 -0400 To: freebsd-hackers@freebsd.org From: Zdenek Radouch Subject: postscript printer handshake problem Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Problem: I don't know how to configure the spooler to properly handshake with a postscript printer (via standard parallel port). Background: I am trying to improve printer connectivity in my wife's graphic design office. The basic idea I had was to take the direct-attached postscript printers that currently have direct connections to a Mac or PC, and hang them off one of the freebsd machines I have, thus effectively converting the printers to network printers. I did that, and very quickly found out that it does not quite work. Details and my theory: It is not exactly clear to me what's happening since the behavior is complex and the errors are not simply obvious. Additionally, the Windows and Mac postscript drivers seems to have their own issues. some of the problems I see are: [Note that most of the files do get printed OK] 1) some files leave the printer in a busy state (this does not happen with a short postscript test code. This suggests missing Ctrl-D handshake from the spooler. 2) appending Ctrl-D to the files that leave the printer busy causes an extra page to be ejected/printed. Can't explain this. 3) Some jobs result in a extra page printed with the text "%%EOF" on it. I can't understand how the interpreter can let this (DCS comment) through. 4) Some jobs do not get interpreted - the printer spews the postscript source code - very annoying since a 20MB postscript source for a two-page ad with graphics can make the printer waste an entire box of paper. This may be related to 3) above - the printer clearly has a mode to pass ASCII through and print it without any interpretation - the question is how does this happen to a proper postscript source file. It looks like there are at least two problems: 1) the freebsd spooler does not handshake properly with the printer I have been quite ignorant of the lpr subsystem, so I have no idea how it is supposed to work, but based on my understanding of postscript (feel free to correct me), I'd expect the following: The spooler should examine the first couple bytes of the job file and look for the DSC pattern (%!) and use that to decide whether or not the printer is a postscript printer. For a non postscript printer it can simply dump the job file in the printer. When talking to a postscript printer (really a postscript interpreter), the spooler has to send Ctrl-D to indicate the end of the job - the interpreter uses that to reset its current environment upon completion of the current job, then sends Ctrl-D back to the spooler to indicate that the next job can be started. Without the Ctrl-D the printer will assume that more pages are coming and either time out, or possibly fail the subsequent postscript processing because code from the previous job may still sit on the interpreters stack. 2) The windows driver clearly violates the DSC by inserting Ctrl-D at the end of the postscript file (But given the other problems I can see why they'd do that). I'd really appreciate if someone who is familiar with the bsd spooler could comment on this. I am interested in how the spooler code currently works when it comes to handshaking with postscript printers. Of course, any other pointers are welcome; if this is known not to work, let me know, too. (BTW, the machine with the spooler runs freebsd 3.4 and the printer sits on /dev/lpt0. Also, the Mac and Windows boxes can print without any problems when they are attached directly and using their native spoolers.) Please respond to me directly at zdenek@mediaone.net, I don't read this mailing list. Thanks. -Zdenek To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message