The LaserWriter 4/600 PS ships with a default configuration that sets the cassette tray paper size to US Letter. Customers in European and Pacific countries that use the A4 paper size need to change the default paper size from US Letter to A4 using the Apple Printer Utility paper handling configuration option. Paper sizes such as legal can also be set using the same procedures.
Most Apple LaserWriters use a series of microswitches and actuators to detect the paper size installed in the cassette tray. The universal cassette tray designed to support a variety of paper sizes automatically reconfigures the actuators for the appropriate paper size. The LaserWriter 4/600 PS does not have the capability to detect the paper size and therefore relies on the information stored in the printer's controller circuitry.