• United States

Using U3 to create portable programs

Mar 13, 20064 mins

Last week we began a discussion of U3, an emerging standard for controlling and managing applications stored on a USB, flash or thumb drive.

This is a very cool idea that creates portable programs – in the sense that they can be carried on physical media from one machine to another and be run with or without being installed. When they exit, they leave no data behind.

As cool as U3 is, a serious issue is that it is very narrowly focused, applying only to Windows 2000, XP and 2003. That leaves all those Windows 95, 98 and ME systems out in the cold (and rightly so) along with Macs and Linux.

Programs engineered to be U3-compatible are different from regular Windows programs because U3 applications are not hard-wired to the directory structure or any operating system components on the host computer and are independent of the Windows Registry.

There are three types of U3 applications: U3 LaunchPad (U3LP), U3 LaunchPad+ (U3LP+) and U3 Aware (U3A).

U3LP Applications are Windows applications that are installed on the U3 device along with their configuration data, user preferences and associated files.

U3LP+ applications are like U3LP applications but are bundled with and use the U3 Device API (DAPI) dynamic link library (DLL). The U3 DAPI DLL, which uses C-based function calls, lets applications communicate directly with U3 thumb drive hardware. For example, applications that use cookies stored on the U3 drive or that check the U3 thumb drive’s unique ID must be compliant with U3LP+.

U3A applications are programs installed on the host PC that use the U3 DAPI DLL to detect and communicate with U3 thumb drives inserted into the host. These are standard Windows applications with specific support for U3 devices. The U3 Software Developers documentation gives the following examples of U3A applications:

A Windows Login service that uses U3 smart devices as tokens.

A Windows backup tool that supports U3 devices, enabling data to be securely backed up to a password protected private area on the device.

U3 takes up just over 5MB of thumb drive storage and creates two partitions – the U3 documentation refers to these as memory domains (more may be added) – that the Windows USB drivers interpret as drives. One drive is read-only and emulates a CD-ROM; the other is read/write.

The read-only drive holds three files:, which contains the U3 system files; LaunchU3.exe, which copies the zip file to the host, unpacks it and presents the user interface; and autorun.inf, which automatically runs LaunchU3.exe if the PC’s CD auto-run feature is enabled. LaunchU3.exe also can be installed to auto-run U3 drives even if the PC’s CD auto-run feature is disabled.

The read/write drive can be a public or private area or both. Private areas require that you log on to the DAPI services before you can see their contents; public areas are visible as soon as the U3 thumb drive is mounted by the Windows USB driver.

On a typical PC, inserting a U3 thumb drive will cause the LaunchPad.exe program to run; then, if the read/write drive is public, it opens and the program appears in the system tray.

Clicking on the LaunchPad.exe system tray icon presents a user interface with a list of the programs installed on the U3 device, as well as a list of functions including Explore U3 Drive, Manage U3 Programs, Status and Settings, Help and Support, About U3 Drive and Download Programs. Vendors building U3 products can add their own logos and links to the interface.

The Manage U3 Programs function lets you add or remove any program, shows you information about each program (description, program size, last run and so on) and lets you set it to run automatically when the LaunchPad loads.

What is the U3 system like in use? You can find out next week.

In the meantime, what are you using USB-flashthumb-whatever drives for? Frank admissions to Bob can admit as well. Oh, and check out Gibbsblog.


Mark Gibbs is an author, journalist, and man of mystery. His writing for Network World is widely considered to be vastly underpaid. For more than 30 years, Gibbs has consulted, lectured, and authored numerous articles and books about networking, information technology, and the social and political issues surrounding them. His complete bio can be found at

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