The first "real" handheld - Atari Portfolio

In the year 1989, Atari released the world's smallest IBM-compatible computer: the Atari "Portfolio".
Atari didn't develop this computer on their own, they just bought the british company "DIP" and released their product under the Atari-label, as they did with the "Lynx" (by Epyx) and somehow with the "Jaguar" (by Flare).
The Portfolio has some "Office" applications built-in, launchable from the DOS environment or directly via hotkeys. Those applications are:

1. Text processor
2. Address and phone book
3. Spreadsheet (255 rows x 127 columns)
4. Time manager (alarms ring even if the Portfolio is turned off)
5. System configuration utility
 

The DOS (2.11) compatible operating system is booted from ROM and doesn't need any RAM to offer more available memory for the programs and data.
The Portfolio can be expanded by floppy drives, memory-cards, a parallel-port, a serial-port, a card reader, memory-expansion-modules, etc. via the "Portfolio Bus".
The latest developments are a ZIP (!)-compatible driver and the possibility to hook up any IDE-compatible drive to the Portfolio.
As in many cases, Atari was way ahead of its time...