A platform for portable Windows applications on USB flash drives from U3 LLC, Milpitas, CA (www.u3.com). Known as "smart drive computing," U3 introduces a computing paradigm with a new concept: the applications are portable, rather than the computer.

Both the U3-enabled application and the user's data reside on a U3 flash drive, and most drives are U3 compliant. The application can be run on any Windows 2000, XP or Vista computer without permanently storing any data or changing any settings on the computer.

Founded in 2004 by M-Systems and SanDisk, U3 sells software licenses to USB drive manufacturers and works with the fabricators that make the controller chips. The name U3 was coined from the marketing concept of "You: Simplified, Smarter, Mobile."

Launch and Run Without a Trace
The U3 application can be set to launch immediately. Like software on a hard disk, the U3 application is read into memory and executed. However, when the smart drive is removed, there are no data or altered Registry settings remaining on the computer. The computer is used only as a processing engine, which means any computer can be used.

The User Interface
Launchpad is the name of the user interface to the drive's contents and the user's personal workspace. Launchpad is currently a requirement, but it is expected that third-party applications will be created without using the Launchpad in the future.

Developing the U3 Application
Applications must be modified to become U3 compliant. Applications that do not use the Registry need only be wrapped in an XML-based U3 header, and simple applications can be changed to avoid the use of the Registry. However, programs that rely on the Registry and/or COM software components (see COM) must communicate with U3 functions in the drive via the U3 Device programming interface (API). Programmers use the U3 software development kit (SDK) to make their programs U3 compliant. See USB drive.