updated 01:50 pm EDT, Fri April 4, 2008
Windows 7 Emu Layer
Microsoft's next version of Windows will represent a large enough break from the codebase of Vista that the company will have to implement a backwards compatibility layer similar to earlier versions of Mac OS X, according to reports from a user familiar with the early versions of the new software. As many of the application programming interfaces will be fundamentally incompatible with the earlier OS, Microsoft will reportedly no longer support programs from earlier Windows versions; as a result, the company will need to introduce a distinct compatibility layer to support earlier programs.
The solution currently implemented for the problem will bear a strong resemblance to Apple's Classic implementation for Mac OS X. Microsoft will create a single, unified application interface that will be called whenever a legacy program needs to launch. It effectively creates a virtual machine for these applications and leads them to believe their normal environment exists, according to the claims.
The foundation of the new operating system is said to be crucial to staying compliant with antitrust rulings that require Internet Explorer not be forced on to users; the web browser's rendering engine will allegedly be present but only when invoked by a legacy app that requires it.
Microsoft has not publicly discussed most details of Windows 7, which is not anticipated until late 2009. However, the company has often stressed software compatibility whenever possible and still allows Vista to run very old Windows software in an effectively native mode.