The first commercially released Newton model. Not to be confused with the MessagePad 100 which shares the same model number (H1000) and form factor. The prerelease version of the device was originally called the Notepad. The name was changed to MessagePad to better reflect its communication capabilities. Commonly referred to as OMP.
The term “Original MessagePad” can also refer to any non-upgraded MessagePad, such as a MessagePad 2000 without the optional memory expansion.
Internet Archive: Newton MessagePad: Description
Internet Archive: Newton MessagePad: Technical Specifications