Released in 1981 by the Osborne Computer Corporation, the Osborne 1 is considered to be the first true portable computer - it closes-up for protection, and has a carrying handle. It even has an optional battery pack, so it doesn't have to plugged into the 110VAC outlet for power.
While quite revolutionary, the Osborne does have its limitations. For example, the screen is only 5" (diagonal) in size, and can't display more than 52 characters per line of text. To compensate, you can actually scroll the screen display back and forth with the cursor keys to show lines of text up to 128 characters wide.
The Osborne was designed with transportation in mind - it had to be rugged and able to survive being moved about. That's one reason that the screen is so small - a larger and heavier screen would be more susceptable to damage.
The two pockets beneath the floppy drives work great for floppy disk storage, although the Osborne modem also fits perfectly in the the left pocket and plugs into the front-mounted "modem" port.
Designed as a true portable computer system - it can be considered airline carry-on luggage, and it will fit under the passenger seat of any commercial airliner.