There were many Keyboard accessories made for Palm OS. Each keyboard required its own drivers to work. Without those drivers, the keyboards are useless.
List of Keyboards, and Drivers
TravelBoard 634 (PalmOS)
Targus Universal Infrared Keyboard PA870U (PalmOS, PocketPC)
https://web.archive.org/web/20011122122116/http://www.targus.com:80/downloads/PA800v151.prc
Fellowes Type N Go (PalmOS)
PDA Mouse (PalmOS)