HP Color LaserJet 4700 Printer series - Manual (Page 287)

6. Align the groove on the side of the flash memory card with the notches in the connector and push
it in the slot until it is fully seated.
CAUTION Do not insert the flash memory card at an angle.
NOTE The first flash memory slot marked "Firmware Slot" is reserved for firmware only.
Slots 2 and 3 should be used for all other solutions.
7. Align the formatter board in the tracks at the top and bottom of the slot, and then slide the board
back into the printer.
ENWW Installing a hard disk, memory, and fonts 271