REX 5000

The REX firmware was written by Starfish Software, and the hardware was manufactured by Citizen Electronics.

Earlier models in this line (the Rex and the Rex-3) had almost no input possibilities except to download data when installed in a host computer or in a docking station; the Rex 5 added a sixth button and introduced a modal input method.

(The later REX 6000 again had only five buttons, but included a touch screen.)

The REX 5000 was repackaged by Motorola as the StarTAC ClipOn Organizer, which piggybacked onto digital versions of their popular StarTAC phone (as well as some Timeport models), expanding the capabilities of the phone from having a capacity of 100 contacts to 1000, and adding calendar and note functionality.

The REX 5000 and StarTAC ClipOn Organizer, like earlier models of the Rex, utilized Starfish Software's TrueSync for data synchronization.