Windows 8.1 is set to roll out to current Windows 8 users on October 17th, with general availability on October 18th. However, did you know that the operating system update isn't necessarily finished yet even though it has already hit RTM (Release To Manufacturing)?
Even though Windows 8.1 has reached RTM and is nearing its general availability, Microsoft will also be releasing a "GA Rollup A" update upon the release of the operating system. Call it an update for the update, if you will. This update will finalize the Windows 8.1 code, since technically Windows 8.1 isn't finished yet even though it hit RTM.
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Windows 8.1 'GA Rollup A' update will finalize the Windows 8.1 code, comes with fixes | WinBeta