How did Microsoft keep Surface a secret for so long? There were rumours about a Microsoft Windows RT tablet on and off for months, but never with enough detail to make them credible.

Read our hands on Microsoft Surface tablet review.

Microsoft has a major manufacturing design setup in what it calls the Garage, full of 3D printers, injection moulding machines and computer-controlled laser cutters.

But that's not where it worked on the designs for Surface because it's far too public. Instead, the design team initially worked in what Stevie Bathiche (pictured below), Microsoft's hardware maven, calls an underground bunker with no windows.

Stevie Battiche

When the team outgrew that they moved above ground into a larger building; this one did have windows but it also had the kind of security you associate with bank vaults (or Microsoft's cloud data centres for services like Office 365, which have guards with guns and take biometric verification to get into).

Getting into the Surface building means going through airlock-style doors; the outer door has to close before you can get through the second door and go inside, so you know there's no-one sneaking in behind you.

Inside the underground bunker, the Surface team were experimenting with designs, from 3D printed mockups to get the size, shape and arrangement right to testing the performance of the Wi-Fi antennas.

A paper prototype of the Microsoft Surface tablet

Microsoft hasn't said whether Surface uses 802.11n or the next Wi-Fi standard, 802.11ac, which relies more on multiple antennas to get higher bandwidth, which also reduces the power it needs (because it can send the data and turn the radio off more quickly).

Microsoft didn't just come up with one design and build it; they went through large numbers of prototypes. "We care about the bigger idea, but also the smallest detail," Bathiche said; "it takes iteration to make great devices and each time we made one of those revisions [Surface] got better and better."

Kickstand

: "The idea was to make it sound like the door of a sports car closing"

One of the things Microsoft kept working on was the sound of the hinged kickstand snapping shut. For something as thin as a credit card, it makes a surprisingly firm and satisfying clunk as it snaps into place.

The idea was to make it sound like the door of a sportscar closing once you've climbed in. "We wanted to get the sound right," said the head of the Surface team, Panos Panay; "we wanted to get that visceral feeling, that emotional connection.

"We created a specification for the sound [we wanted] and we iterated over and over again, testing it in an anechoic chamber."

The reason for all this? Microsoft wanted the sound to give you confidence that the kickstand is safely shut so you don't have to worry about it getting in the way. "We want to make it so it's there when you need it and it just goes away when you don't."

A stack of prototypes for the Microsoft Surface tablet

There's a lot under the surface of the Surface tablet, in terms of components and design, as well as the fanatical attention to detail.

What resolution is the Surface screen?

As well as Apple levels of secrecy and an Apple-style attention to detail in the physical design of the Surface tablets, Microsoft appears to have taken another leaf out of the Cupertino-based firm's book when it comes to describing the specifications.

It's not going as far as Apple, who doesn't even give the new iPad its own model name – we're calling them Surface RT and Surface Pro, but the official monickers are the typical Microsoft 'does what it says on the tin' names, Surface for Windows RT and Surface for Windows 8 Pro.

The many stages of the Surface design process

But Microsoft isn't giving the speeds of the processor or any details beyond ARM and Ivy Bridge Core i5 (though NVIDIA claims it's a Tegra 3 inside the Surface RT), the battery life or the actual screen resolution.