Summary Box: Microsoft sees future in Windows 8

COMING FROM MICROSOFT: A test version of Windows 8 will be unveiled Wednesday in Barcelona. The mass market release is expected in September or October.

WHAT IT IS: The new Windows version is radically different from its predecessors. The system won’t have Microsoft’s familiar “Start” menu, for instance. There’s also a version that can run on the more tablet-friendly microprocessor technology licensed by ARM Holdings.

SIGNIFICANCE: Microsoft hopes to keep milking revenue from a PC market that appears to be past its prime, while trying to gain a stronger foothold in the more fertile field of mobile devices.