Newton

The Newton platform was Apple's first attempt in the handheld market. The devices ran Newton OS.

Hardware models
From Apple:
 * MessagePad (also known as the H1000, OMP or Original MessagePad)
 * MessagePad 100 (same hardware as OMP, but newer system version)
 * MessagePad 110
 * MessagePad 120
 * MessagePad 130
 * eMate 300
 * MessagePad 2000
 * MessagePad 2100

From Motorola:
 * Motorola Marco

From Sharp:
 * Sharp ExpertPad PI-7000 (equivalent to OMP)
 * Sharp ExpertPad PI-7100 (equivalent to MP 100)

From Digital Ocean:
 * Tarpon
 * Seahorse

From Siemens:
 * Siemens Note Phone

From Harris:
 * Harris SuperTech 2000

Discontinuation
The Newton project was briefly spun off from Apple Computer into a wholly-owned subsidiary company, Newton Inc., but was reabsorbed 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.