Microsoft has opened up its Windows CE source code to allow device makers to make changes to the OS and then sell on the results - the first time the company has ever allowed people to work independently with its code.

Don't think this is open source or open source licensing though. Third parties will not be required to make any modifications available to Microsoft, nor to anyone else. The plan, of course, is to put CE on a stronger footing.

Windows CE was developed for devices including consumer electronics, wireless routers, industrial controllers, handheld computers, set-top boxes, VoIP phones and thin clients. It competes with proprietary operating systems as well as with versions of Linux designed for embedded use (see "Picking the right mobile platform").

"The option to ship derivatives of Windows CE will give device makers another opportunity to innovate, thus we will see a further expansion of the types of devices that are powered by Windows CE," said product manager John Starkweather.

The expanded source licensing will come with Windows CE 5.0, previously codenamed Macallan, and released in beta in March. The software succeeds Windows CE 4.2 and is scheduled to be released to manufacturing on 9 July. General availability should follow shortly thereafter.

More than 2.5 million lines of code will be available, including the kernel, graphical user interfaces, file system, device drivers and Web server. For Windows CE 4.2, Microsoft made about two million lines of code available, which users were allowed to use only for reference and debugging purposes. Previously, the Windows CE Shared Source Premium programme, launched last year and limited to specific companies, provided almost all the CE source code but modifications had to be shared with Microsoft.

Under the new programme, any licensee in any country will be able to access to the source code, Starkweather said. The Windows CE Shared Source Premium program will continue, and Microsoft may expand it to include some additional companies.