(You: Simplified, Smarter, Mobile) An earlier platform for portable Windows applications from U3 LLC, Milpitas, CA. Both the U3-enabled app and user's data resided on a USB drive. U3's "smart drive computing" introduced the concept of portable applications. Founded in 2004 by M-Systems and SanDisk, U3 evolved into StartKey from Microsoft and SanDisk. Launch and Run Without a Trace Like software on a hard disk, the U3 application was read into memory and executed from the USB drive. However, when the drive was removed, there were no data or altered Registry settings left in the computer. Any Windows PC could be used merely as a processing engine. Developing the U3 Application Applications had to become U3 compliant. Apps that did not use the Registry were wrapped in a U3 header, and those that required the Registry had to communicate with the U3 programming interface (API). See USB drive and COM.