Microsoft has relaxed a Windows 8 certification requirement to allow devices with lower resolutions, a move analysts said signaled Microsoft would soon join the accelerating shift to smaller, less expensive tablets. "The sub-eight-inch part of the tablet market will be growing this year to about 55% of the entire market," said Bob O'Donnell, an analyst with IDC. "Microsoft hasn't even been playing in that segment, and they needed to do something."