MICROSOFT has announced an upgrade to its MS-DOS operating system that has a refined data protection component to run with the DoubleSpace disk compression technology introduced with version 6.0. MS-DOS 6.2 will be available to most users for little or no cost. It also has a host of features for faster and more effective performance, including an integrated disk analyser and repair tool, automatic disk scanner, and enhanced start-up and SmartDrive. Built into MS-DOS 6.2 is DoubleGuard, a data protection feature that works with the DoubleSpace disk compression technology that was introduced in MS-DOS 6. DoubleGuard prevents data from the corruption experienced by some users as a result of underlying, pre-existing hardware problems, or by memory-resident programs. Steve Tsui, systems product manager of Microsoft Hong Kong, said: ''MS-DOS 6.2 includes the software equivalent of air bags and anti-locking brakes to make disk compression as safe and easy as possible.'' MS-DOS 6.2 has other enhancements to DoubleSpace compression that make using disk compression and system software safer, easier and faster. Its suggested retail price, $120, is intended to cover manufacturing and distribution costs. Users of earlier MS-DOS versions can obtain a fuller-featured upgrade for a promotion price of HK$499 until the beginning of March 1994, after which it cost $1,032.