FAQ: What we don't know about Microsoft's Surface tablet

Computerworld - Microsoft's introduction Monday of the new Surface tablet may have been dramatic -- one analyst said it was "radical" -- because of the company's decision to circumvent its hardware partners -- but the presentation left as many questions unanswered as it resolved.

Some are critical to the Surface's success, like its price point, while others may influence only a minority of would-be buyers as they weigh it against those already in the market, such as Apple's iPad, the current king of the tablet hill.

We've selected some of the up-in-the-air topics, and although we don't have answers for most, we've tried to use what is publicly known about tablets -- and Microsoft -- to give you some clues.

If you have questions you suspect Microsoft didn't answer this week, you can either wait for more revelations from the company -- it will undoubtedly disclose more as a launch grows closer, probably in dribs and drabs -- or add them to the comments below. (We'll likely do a follow-up to this initial Q&A a little later.)

What will these tablets cost? We don't know. Microsoft declined to set prices Monday, saying only that the Windows RT Surface (just "Surface" from here on out) would be "competitive with a comparable ARM tablet," and that the Windows 8 Pro Surface (Surface Pro) would cost about the same amount as "an Intel ultrabook-class PC."

Without definitive information from Microsoft -- not surprising since it's three, maybe four, months until Windows RT tablet goes public, six or seven before the other one shows up -- analysts are forced to guess. Their estimates for the Surface ranged from a low of $400 to a high of $700, while the Surface Pro will probably cost anywhere from $800 to more than $1,000, with many betting on the latter as the target.

When will they go on sale? Only Microsoft knows. The company also declined to pin itself to a launch date.

The most it would commit to was that the Surface would debut around the same time as Windows 8's release -- most expect that in September or October -- and that the Surface Pro would follow 90 days later.

That means the Pro could miss the holiday season if, for example, Windows 8 doesn't ship until the second half of October -- as did Windows 7 in 2009 -- which would push the Surface Pro launch into January 2013.

How long will the tablets' batteries last between charges? We have an idea, but it's just a guess.

Microsoft spelled out the watt-hour (Wh) capacity of the two tablets' batteries, but oddly, made no claims about how long those batteries would keep each device running under average conditions. (A 10Wh rating means the battery can produce one watt of power for 10 hours, or, say, 10 watts of power for one hours.) The Surface's battery is rated at 31.4 Wh, while the Surface Pro's is 42.

Some back-of-the-envelope comparisons between the Surface and new iPad (42.5 Wh), and between the Surface Pro and the 11-in. MacBook Air (35 Wh), results in rough -- very rough -- estimates:

• Surface Windows RT: 7.5 hours
• Surface Windows 8 Pro: 6 hours