• Illustration: The Embedded OS-Reference Platform Relationship
• Chart: Embedded OS Roadmap at a Glance
• Illustration: Windows CE Voice over IP

The latest Windows CE release illustrates that Microsoft’s embedded OSs are maturing, and although the general embedded market remains important to Microsoft, future releases will target specific device markets by adding a few key technologies. Microsoft’s embedded strategy has always focused on making it easy for developers to get small, connected, non-PC devices to market quickly. Microsoft’s embedded OS roadmap shows this strategy is being refined to help customers target specific device markets, but some might still struggle over whether to start with an embedded OS (Windows CE .NET or XP Embedded) or a reference platform (Pocket PC or Windows-Powered Smartphone).

There are three key Windows embedded products:

• Windows CE (CE), which is a real-time, small-footprint version of Windows designed from scratch as an embedded OS that allows developers to create a variety of non-PC devices running on numerous different processor types
• Windows XP Embedded (XPe), which is a version of Windows XP Professional that allows developers to create an embeddable OS image with only the Windows XP components that their applications need
• Windows 2000 with the Server Appliance Kit (SAK), which is a toolkit that allows developers to build server appliances based on Windows 2000 Server technologies.

CE and the SAK will follow a similar path: there will not be any major architectural or feature changes in future releases of these products, but incremental improvements will address performance, improve the tools, and target key market segments. In contrast, XPe will follow the Windows client or desktop OS platform roadmap, including the features that are part of subsequent Windows client releases.

Overall Embedded Strategy

As Microsoft fine-tunes its embedded Windows strategy for CE and the SAK to better target key specific device and appliance markets, the overall strategy for all three products remains unchanged: to provide embeddable versions of Windows that OEMs and ISVs can use to quickly build non-PC devices with significant processing power and connectivity ("smart" devices), such as handheld computers, industrial robots, kiosks, media players, personal digital assistants (PDAs), and set-top boxes, and to ensure that these devices can consume Windows services (e.g., play Windows Media files, connect to servers such as Exchange, or use Web services). Microsoft implements this strategy by supporting commodity hardware and extending the Windows programming model to embedded devices.

Supporting commodity hardware. A key tenet of Microsoft’s embedded Windows strategy is to support commodity hardware platforms. For example, because Windows XP Embedded (XPe) uses the same binary executables as Windows XP Professional, and the Server Appliance Kit (SAK) builds on top of Windows 2000 Server, they both run on the same generally available—and therefore relatively inexpensive—hardware as their retail counterparts. Windows CE also supports not only commodity hardware based on Intel x86 processors but additional processor families, including ARM, Intel’s XScale, MIPS, and SHx.

Extending the Windows programming model. Again, because XPe and the SAK are based on their respective retail counterparts, they run the same applications, and developers can use the same tools, processes, knowledge, and experience to develop custom applications. CE is different—it was developed from scratch as a real-time embedded OS. Therefore, it cannot run Windows applications and porting over Windows applications can be difficult, if not impossible. But a developer who knows how to write Windows applications can extend her knowledge of Windows programming and development tools to the Windows CE API set. Similarly, if developers are moving to Microsoft’s latest programming model, based on the .NET Framework, then a logical extension also exists: CE supports the .NET Compact Framework, a subset of the .NET Framework that is designed for embedded and mobile devices.

Two Routes to Market

Although Microsoft’s overall embedded Windows strategy—make it easy to get smart devices to market—is simple, confusion arises because there are two routes to market: the embedded OS route and the reference platform route.

The embedded OS route. A customer using the embedded OS route to market designs a hardware device and uses an embedded Windows OS and its tools to create the device's software. For example, an OEM or corporate developer who has designed a handheld computer for couriers could create software for this device using CE and its Platform Builder tools, or XPe and the Windows Embedded Studio tools. In either case, the designer could then use Visual Studio to write custom applications or software. The advantage of this approach is increased flexibility: the developer can choose which features of the embedded OS to include in the image and can then write highly customized applications. In addition, the latest technology is often available as part of the embedded OS first, but reference platforms are often based on older versions of the embedded OS. For example, Pocket PC 2002 is still based on CE 3.0, even though the embedded OS is now CE 4.2. This route requires hardware design skills and more software development work and therefore increases development time. However, the result is a device that is unique and well-suited to the designer's specific task.

The reference platform route. A customer using the reference platform route selects a reference platform that is a combination of hardware and software designed by Microsoft and customizes that design for its own use. For example, an OEM or corporate developer might use the Pocket PC 2002 reference design with the XScale processor, with 32MB of flash ROM, and 240 x 320 backlit color displays. In addition to the CE OS software, Pocket PC 2002 includes a stylus-only user interface and applications such as "pocket" versions of Internet Explorer, Outlook, and Word; drivers for common hardware, such as the sound recorder; and connectivity interfaces, such as Universal Serial Bus (USB). Selecting the reference platform allows the developer to jump-start development on a specific type of device, such as a PDA. This approach is especially powerful for devices targeting high-volume markets, where the developer can offset the higher costs of a prebuilt hardware and software platform by getting a device to market quickly and concentrating on value-added applications that distinguish the device from others. The disadvantage is that the developer may not have access to the latest embedded OS features, and there is less ability to differentiate a device from competitors that also use the reference platform.

(See the illustration "The Embedded OS-Reference Platform Relationship".)

Embedded OS Product Futures

Microsoft will release new versions of Windows CE and the SAK in the near term, while the next major update to Windows XP Embedded will not occur until after Microsoft ships "Longhorn," the next version of the Windows desktop OS. (For a summary of the roadmap, see the chart "Embedded OS Roadmap at a Glance".)

Windows CE .NET 4.2

Microsoft has released Windows CE .NET 4.2, the base CE OS, to manufacturing with an expected availability date of June 2003. It is likely that CE .NET 4.2 will form the basis of the next Pocket PC (Pocket PC 2003) and Smartphone reference platforms.

Most notably, the release includes new support for Voice over IP (VoIP), which will make it easier for CE .NET 4.2 to be used in devices such as phones and communication-oriented PDAs. (For more information on VoIP support in CE .NET 4.2, see the illustration "Windows CE Voice over IP".)

CE .NET 4.2 also includes improved networking support for the Layer 2 Tunneling (L2TP) and IP Security (IPSec) protocols, which should make Virtual Private Network connections from CE devices more secure; a new version of Internet Explorer (6.0) for CE, which could improve mobile browsing scenarios; and the Windows Media 9 Series codecs, which will enable the devices to use highly compressed digital media files that download more quickly and take up less disk space.

In addition, CE .NET 4.2 will include 18 software components from eight Windows Embedded partners, such as board support packages (software that implements the device drivers for a standard development hardware board, allowing the rapid evaluation and development of a solution) and hardware-specific device drivers, to provide additional software options for embedded developers.

Microsoft does not appear to be using this release of CE as an opportunity to remove the .NET moniker from the product name, as it did recently with Windows Server 2003 in an attempt to refocus the .NET brand on the appropriate development technologies (rather than products).

Windows Server 2003 Standard Edition for Embedded Systems

Microsoft is working on a new version of the SAK tentatively called Windows Server 2003 Standard Edition for Embedded Systems, which is scheduled for release within 120 days (Aug. 2003) of the general availability of the retail server product (Apr. 2003).

The most obvious change to the SAK will be a change from the current Windows 2000 Server to the recently released Windows Server 2003 and the resultant availability of new Windows Server 2003 features, such as support for Volume Shadow Copy and Internet Information Server (IIS) 6.0, which should help the SAK target storage and Web blade devices.

A more subtle change involves the role of the SAK. The Windows Server 2003 SAK will target single-purpose, headless (no monitor or keyboard) server appliances that perform tasks such as file and print serving or backup, and the Windows Storage team might produce a specific SAK for storage appliances such as network attached storage (NAS) devices. Similarly, the Windows Security team might produce a customized SAK for firewall appliances.

Windows XP Embedded

No major changes (other than tracking the service packs of the retail Windows XP product) are anticipated for Windows XP Embedded, which is being used to build embedded devices—such as game consoles, kiosks, and point-of-sale devices—until after the next major release (code-named Longhorn).

Microsoft says that customers are not asking for Windows Server 2003 Embedded; a product that would be similar to Windows XP Embedded but would allow developers to build an OS image based on the components of Windows Server 2003 rather than Windows XP. This is due to the fact that the SAK already allows customers to build server appliances, and it will be upgraded for Windows Server 2003. In the same vein, Microsoft says that although the Windows base team has componentized the binaries and documented the dependencies for the additional OS components in Windows XP Tablet (such as inking recognition service and journal application) and Windows Media Center (personal video recorder application) editions, customers have not asked for those components to be added to Windows XP Embedded.

Reference Platform Planned for Media Players

Microsoft will continue to roll out new reference platforms to facilitate development of devices targeting a specific market. The latest example is digital media players.

During his keynote address at the 2003 International Consumer Electronics Show Bill Gates, Microsoft’s chairman and chief software architect, unveiled the first prototype of a portable media player based on a planned device reference platform code-named Media2Go. This new reference platform will facilitate the design and development of smart personal media players, such as handheld personal media players that let users download, store, and play back digital media content, such as video, music, and photos.

Although few details are available about this reference platform, it is scheduled for release in the second half of 2003, and OEMs Creative, iRiver, Samsung, Sanyo, and ViewSonic have agreed to build devices based on it.

Availability and Resources

The Windows Embedded OS products are available from distributors. Distributors for each product are listed at the product’s Web site.

For more information on Windows CE .NET, see www.microsoft.com/windows/embedded/ce.net.

For more information on Windows 2000 with the Server Appliance Kit, see www.microsoft.com/windows/embedded/sak/.

For more information on Windows XP Embedded, see www.microsoft.com/windows/Embedded/xp/default.asp.

For more information on the Pocket PC, see www.microsoft.com/mobile/pocketpc/default.asp.

For more information on Smartphones, see www.microsoft.com/mobile/smartphone/default.asp.

For more information on Volume Shadow Copy, see "Windows .NET Server Supports Enterprise Storage" on page 3 of the Dec. 2002 Update.

For more information on Media2Go, see "New Clients for Windows Media" on page 19 of the Feb. 2003 Update and www.microsoft.com/windows/embedded/devices/pmp/default.asp.