Xerox Phaser 840 Service Manual page 173

Phaser 840/850 - Running Reset PE NVRAM to Default or Clear PS NVRAM
downloads a file to the printer that performs the indicated reset function; there is no
confirmation or cancel function.
Fig 4-13 Resetting print engine NVRAM menu item
Fig 4-14 Clearing PostScript NVRAM menu item
Diagnostics and Adjustments 4 - 157