HP LaserJet 5100 Printer series - Manual (Page 164)

C-8 Printer Memory and Expansion
ENWW
Installing EIO Cards/Mass Storage
Turn off the printer before installing the EIO card or mass storage
device.
See Figure 24 for orientation and location of the EIO card or optional
mass storage device, such as an optional hard disk.
Use HP Web JetAdmin to delete files from a mass storage device.
For more information, see the printer software help.
Figure 24 Installing EIO Cards or Mass Storage Devices