Oki ES6450 User Manual page 66

For macOS
 Depending on the timing when the printer is added, the information for the expansion tray unit may have been set.
1
Select [System Preferences] from the Apple menu.
2
Click [Print & Scan].
3
Select this machine, and click [Options and Supplies].
4
Select the [Options] tab.
5
Select the total number of trays from [Available Trays], and click [OK].
Connecting to the PC after preparing this machine
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