Newton

Newton was Apple's first attempt to create a mobile platform for the handheld market. The devices ran Newton OS.

Apple Computer

 * MessagePad (also known as the H1000, Original MessagePad, or OMP)
 * MessagePad 100 (same hardware as OMP, but with newer version of Newton OS)
 * MessagePad 110
 * MessagePad 120
 * MessagePad 130
 * eMate 300
 * MessagePad 2000
 * MessagePad 2100

Digital Ocean

 * Seahorse
 * Tarpon

Harris

 * Harris SuperTech 2000 (based on the MessagePad 130)

Schlumberger

 * Schlumberger Watson

Sharp

 * Sharp ExpertPad PI-7000 (based on the Original MessagePad)
 * Sharp ExpertPad PI-7100 (based on the MessagePad 100)

Siemens

 * Siemens Note Phone
 * Siemens Online Terminal

Discontinuation
The Newton project was briefly spun off from Apple Computer into a wholly-owned subsidiary company, Newton Inc. However, it was re-absorbed in July 1997 when Apple CEO Gil Amelio was fired by the board and Steve Jobs took over as interim CEO. Jobs cancelled the Newton in 1998, causing fans and developers to protest at the Apple campus in March.

Two ex-Apple Newton developers later founded Pixo, the company that created the operating system for the original iPod.