Apple ColorLaserWriter 12/600PS - Manual (Page 156)

3 Remove the universal paper cassette from the feeder.
You don’t need to fill the cassette with paper at this time.
4 Place the feeder base where you want the printer to be located.
Orient the base so that its paper cassette and the printer’s paper cassette will
be on the front side when the printer is on the feeder base.
5 Remove the paper cassette from the printer.
Squeeze the handle, lift
slightly, and pull the cassette out.
131 Installing Options