For those with Intel-compatible machines, the OS will be available in two versions – Windows 8 and Windows 8 Pro.
And for those with devices, largely tablets, powered by ARM-designed chips there will be a Windows RT version.
Microsoft wants to simplify how it markets Windows 8, which is expected to launch in autumn 2012.
The complex flavours of past Windows – from basic to home, premium to ultimate – have become something of a joke among tech experts.
Microsoft has called Windows 8 the most significant redesign of the Windows interface since its groundbreaking Windows 95 OS.
The ARM version of the OS is the newest edition and reflects Microsoft’s desire to unify the engine known for running desktop computers with that for tablets and smartphones. Windows RT will sit alongside Apple’s iOS and Google’s Android operating systems.
It announced the new flavours on its Windows blog.
Many of those reacting to the announcement were unimpressed by the name for its ARM version.
“You guys are doing a phenomenal job with Windows Phone, Windows 8, etc, which makes the naming of ‘Windows RT’ all the more maddening. You’re trying to simplify the rest of the ‘Windows Live’ properties, which I applaud, but then you go with Windows RT? Does. not. compute,” said Michael Jenke, summing up the views of many responses to the blog.
In an earlier 8,600-plus word blog post Windows president Steven Sinofsky detailed the “energising and daunting” challenges in developing Windows on ARM.
A preview version of Windows 8 launched late last year and more than 100,000 changes had been made since the developer version went public.
For the first time since its inception, the trademark Windows “Start” button will no longer appear – instead being replaced by a sliding panel-based menu.
In a footnote in its blog, Microsoft said that there would be an adapted version of Windows 8 Pro for businesses.