Franklin Rolodex Electronics REX PC Companion (1997)

 The REX redefined the notion of portable. This credit-card-size device was powered by two watch batteries, measured just a quarter of an inch thick, and was designed to fit into a notebook's PC Card slot. Its design was simple--just a black-and-white, 160-by-98-resolution screen, and five navigational buttons to access such functions as calendar, contacts, and even memos. Although you couldn't enter data into the first version (about $179 with cradle), the REX proved a convenient portable companion.