Microsoft revealed that it will begin sales of its Surface tablet devices in October 2012, in line with the introduction of the next version of its Windows operating system, Windows 8.

In a regulatory filing, the company said: “The next version of our operating system, Windows 8, will be generally available on 26 October 2012. At that time, we will begin selling the Surface, a series of Microsoft-designed and manufactured hardware devices.”

The company did not detail whether both versions of Surface – one powered by an ARM-based processor, and another by an X86 chip – will be launched at the same time. It was previously said that the X86 version will follow some three months after the ARM unit.

In addition, pricing details have not been revealed.

Microsoft also did not disclose its intended launch plans for Windows Phone 8, its next smartphone operating system release, although this may fall in-line with the Windows 8 family debut.

The filing did reveal a number of areas where Microsoft feels it is facing challenges.

With regard to Surface, it said that it will “compete with products made by our OEM partners, which may affect their commitment to our platform”. Microsoft has traditionally shied away from such competition, instead opting to focus on its position as a platform provider.

It also said that as it competes with a “vertically integrated” model, with software, hardware and services delivered by the same company, “our competitors have been in the market longer and in some cases have established significantly large user bases”. The shift to such a model will also reduce its operating margin.

And it acknowledged the importance of its rivals’ app stores, which provide “disincentives for users to switch to competing platforms”. In order to address this, Microsoft said it must “successfully enlist developers to write applications for our marketplace and ensure that these applications have high quality, customer appeal and value”.