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Microsoft on Tuesday gave its first detailed look at the next major update to Windows, which it has decided to call Windows 10.

The software, expected to be released in final form next year, is designed to run across the broadest array of devices, with screens ranging from four inches to 80 inches, with some devices having no screens at all.

“Windows 10 will be our most comprehensive platform ever,” Windows chief Terry Myerson said at a briefing with reporters in San Francisco. “It wouldn’t be right to call it Windows 9.”

In addition to being the next version of Microsoft’s PC operating system, Windows 10 will also be the next major release for Windows Phone as Microsoft moves to a single OS for PCs, phones and tablets.

Visually, Windows 10 resembles Windows 7 as much as Windows 8. Many of Windows 8’s user interface features are still present, but they are tucked into a more traditional Windows interface. Both classic and new-style apps run side-by-side with a less jarring distinction between the two types of programs.

Phones will have a different user interface from the one shown Tuesday, but Microsoft declined to offer many details on that, saying only that it would be an evolutionary update to Windows Phone 8.1.

A technical preview version of the software will be made available starting on Wednesday, Myerson said. Consumers that don’t mind trying early, pre-release software can download the Windows 10 preview part of a new Windows Insider program. ”

“We’re planning to share more than we ever have before, frankly earlier than we have before,” Myerson said. “We know there are these people that want to live on the edge with us.”

In demonstrating the new software, Windows VP Joe Belfiore demonstrated how the new Windows will work with a wide-range of interfaces, ranging from the very old-school command prompt, to the Windows 7-style task bar to modern touch screens.

Windows 10 represents a critical launch for Microsoft, which has seen exceptionally slow business take-up for Windows 8 during its two years on the market.

An added challenge for Microsoft is that it now has millions of users on touch-screen Windows 8 devices and hundreds of millions of people using older versions of the software with a mouse and keyboard.

Microsoft has a lot of different constituencies to please, not to mention trying to appeal to a generation of new computer buyers that have grown up with iPhones, iPads and Android devices.

While highlighting work that the company has done to appeal toward existing mouse-and-keyboard users, Belfiore said “We definitely see people moving towards touch.”

The company is also working on an approach called “continuum” that would allow convertible laptops to switch between a standard view and a tablet-centric view more similar to Windows 8. Belfiore showed a video of how this could work, but said the feature is not yet far enough along to demonstrate publicly.

While Microsoft is previewing the code now it will be some time before the company reveals other details, such as exact timing and pricing.

Myerson declined to say whether Microsoft will sell Windows 10 differently, such as via subscription or other means. He also said it was too soon to say if Windows 10 would arrive sooner for some types of devices than for others.

Microsoft focused its pitch on Tuesday to business customers, with additional events expected in the coming months to tout features for other audiences.

Myerson said the company will talk more about the consumer features early next year, with plans to release it later in 2015, at some point following the company’s Build conference for developers.

“Mid-next year would be a reasonable time to think about it,” Myerson said.