HP 3500 - Manual (Page 240)

Installing an hp Jetdirect print server card in the hp color
LaserJet 3700 series printer
You can install an HP Jetdirect print server card in the base model printer, which comes
with an open EIO slot.
To install an HP Jetdirect print server card
1. Turn the printer off.
2. Disconnect all power and interface cables.
228 Appendix E Working with memory and print server cards ENWW