Without the HP LaserJet 4si PPD file, correct tray handling and usage is not possible.
We contacted HP and the "Auto Select" and "Trayswitch" features are available on the HP LaserJet 4si. In other words, the two problems:
1) having a paper source of "wherever there's paper" (Auto Select)
2) automatically feeding from another paper tray when the current one runs out (Trayswitching), are supported on the HP LaserJet 4si.
As long as the HP LaserJet 4si PPD is selected in LaserWriter 8.x driver, the Auto Select feature is available as a paper source option. In terms of the Trayswitching feature, this is already built-in to the LaserJet 4si. There is also a feature on the front panel of the printer that allows you to disable any tray so that it is not used in the trayswitching cycle. The default trayswitch setting for the printer is to use the top tray first, and then the lower trays from top to bottom.
You can obtain the HP LaserJet 4si PPD from HP's driver distribution center.
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