Update: Finally! HP Printer Software Update 2.6 for Snow Leopard appears to fix the manual duplex issue. Let me know if you still have page ordering problems after updating. I'm keeping this page alive for those still running Leopard

One of the things that bothered me when I got my CM1312nfi was the fact that the Manual Duplex and Booklet features of the Mac OS X print driver were printing the back sides of the pages in the wrong order, resulting in weird page combinations (e.g. 1-8, 2-7, 3-6, 4-5). If I reversed the order of the sheets before reinserting them into the printer and then reversed the sheet order again after the job was finished, the results were as expected, but it was a pain in the butt doing so.

After fruitlessly trying to get HP tech support to help, I took matters into my own hands. I started digging around in the PPD file for the printer and trying different combinations of parameters. I finally stumbled upon a combination that worked, so I thought I'd share it here. If you'd like to download a ready-to-install PPD file, you can get it here.

   HP Color LaserJet CM1312 MFP Series.gz (Leopard)

If you have your browser set to automatically decompress archive files (the "Open safe files after downloading" option in Safari will do that), control-click on the link and download the file that way. The file needs to stay compressed. This modification should work with the non-nfi version of the CM1312 also, since they use the same PPD.

Copy this file into your "/Library/Printers/PPDs/Contents/Resources" folder, saving the original file in that folder somewhere in case you need to go back to it. Then, go into the Print & Fax preference pane and delete and re-add the printer.

If you'd rather do the modification yourself, here's the procedure:

1. Copy the "HP Color LaserJet CM1312 MFP Series.gz" file from the "/Library/Printers/PPDs/Contents/Resources" folder to the desktop. Make a duplicate copy so you can restore the original if you make a mistake.
2. Double-click on the "HP Color LaserJet CM1312 MFP Series.gz" file now on the desktop. The file will decompress and create a "HP Color LaserJet CM1312 MFP Series" file (without the .gz extension).
3. Open the "HP Color LaserJet CM1312 MFP Series" file (the one without the .gz extension) in TextEdit.
4. Edit the following two lines:

      *DefaultHPFaceOrientation: FaceUp
      *HPManDupTumbleFirstSides: False

   Change "FaceUp" to "FaceDown" in the first line. Change "False" to "True" in the second line. This will allow you to put the pages back into the printer as they come off the printer, i.e. without having to rotate them or flip them over.

5. Save the file.
6. Open the Terminal application and type the following two commands followed by the return key:

      cd Desktop
      gzip -c "HP Color LaserJet CM1312 MFP Series" > "HP Color LaserJet CM1312 MFP Series.gz"

   This will replace the "HP Color LaserJet CM1312 MFP Series.gz" file on the desktop, so you can see the importance of the duplicate copy in step 1.

Alan Somers