Microsoft has shipped the first test version of Windows 8 to PC makers, according to posts on online forums, which means it's on track for a late 2012 release.

Windows 8 is a big deal for Microsoft because it will have special features for tablets -- it will be the first version of the full Windows desktop OS to run on the low-powered ARM processors used in most tablets, and will have a design that works better on touch screens.

The company has struggled to come up with an answer to Apple's iPad, which is replacing sales of consumer notebooks running Windows -- particularly netbooks -- and is gradually making inroads into businesses as well.

The test version of Windows 8 is reportedly being offered through Microsoft Connect, a program for privileged beta testers. Unusually, each invitation to the beta comes with a one-time use code, which should help Microsoft prevent leaks.

Full story: SFGate