A new version of the .NET Framework aimed at developers of embedded devices is available in beta. The .NET Micro Framework was originally developed for use in Smart Personal Objects Technology (SPOT) devices, such as wristwatches, but will also be used in Windows SideShow devices—auxiliary displays built into future notebook computers, keyboards, and other devices. It will show important information, such as an upcoming meeting, even when the device is turned off.

Like other versions of the .NET Framework, the Micro Framework relies on a Common Language Runtime (CLR) to translate C# or VB.NET code into machine instructions for a specific processor. However, unlike other versions of the .NET Framework, which rely on an underlying OS—such as Windows or Windows CE—for key services, the Micro Framework runs directly on a small set of supported microprocessors. A video produced for the Microsoft Embedded Developer Conference (MEDC) indicates that the Micro Framework will run with as little as 200 kilobytes of RAM and will support the ARM7 and ARM9 family of embedded processors. That makes the Micro Framework much smaller than even the smallest versions of Windows CE, and could make .NET an option for a group of programmers that have, until now, been stuck with lower-level tools and languages that are more difficult to use.

The Micro Framework differs from the desktop version and the .NET Compact Framework (used in Windows CE) in other ways. First, because it is intended to run on dramatically smaller devices, its internal architecture is different and uses a different style of garbage collector (the component that reclaims memory when it is no longer used by an application). In addition, although the Micro Framework includes a set of class libraries covering functions such as basic graphics, I/O, networking, and XML support, in many cases these libraries offer less functionality than their counterparts, owing to size constraints. The full version of the .NET Base Class Libraries (BCL), for example, includes 1,450 classes, compared with only 70 in the Micro Framework. Therefore, developers coming from the other versions of the Framework can reuse basic programming skills and their experience with Microsoft's tools, but their source code may need to be rewritten.

More information about the Microsoft Framework is at www.aboutnetmf.com/entry.asp.

The MEDC video describing the Framework is at casting.dlservice.microsoft.com/download/9/C/D/9CD1795D-74BF-43E7-9B27-1BB0F7FAAFD1/dotNET_Micro_Framework.wmv.

SPOT devices are described in "SPOT Devices to Use FM-Based Network" on page 20 of the Feb. 2003 Update.