What operating system do the iPad models use? Do all iPad models completely support iOS 6?

The original Wi-Fi-equipped and Wi-Fi/3G/GPS-equipped iPad models first shipped with iPhone OS 3.2 (subsequently renamed the "iOS"). At the time, it was disappointing to many as this version of the iOS does not support true system-wide multitasking.

However, iOS 4 was released in a few months and the original iPad models support multitasking when upgraded to iOS 4 or later. All subsequent iPad models shipped, or ship, with a version of the iOS that supports system wide-multitasking by default.

However, not all iPad models support iOS 6 and not all iPad models support this version completely, either.

Specifically, iOS support for each iPad model follows:

*Siri and FaceTime over a cellular network are not supported on the iPad 2 even when running iOS 6.

Please also note that once an iPad device has been upgraded to a later version of the operating system, it can be challenging to "downgrade" it back to an earlier version without jailbreaking or other hacks. It's always wise to wait for feedback from other users and a couple of "bug fix" releases before upgrading the operating system.

If you are not sure which iPad you have, see EveryiPad.com's iPad Identification section.

Will operating system updates for the iPad be free like the iPhone or will they cost money like the iPod touch?

As first spotted by MacRumors in the original iPad licensing agreement, the next major version of the operating system (4.x) would be provided free of charge. Indeed, iOS 4 was provided free of charge.

At the time the iPad first was released, operating system updates were free for the contractually bound iPhone, but cost money for the no contract iPod touch. Based on the fact that Apple only stated the next major version of the iOS would be free and that the iPad was not bound by a contract, EveryiPad.com originally speculated that subsequent versions of the operating system presumably would cost money. However, the site also noted that "only time will tell."

In a nice surprise, Apple released iOS 5 at no charge for those using earlier iPad models. Apple released iOS 6 at no charge also, although the original iPad is not supported. At least in the short term, it appears that Apple no longer charges for iOS updates for any devices.

It's also important to be aware that Apple notes operating system "updates and releases may not necessarily include all of the new software features that Apple releases for newer iPad models."

Specifically, Siri and FaceTime over a cellular network are not supported on the iPad 2 even when running iOS 6. These features are supported on more recent iPad models.

Can applications that run on the iPhone and iPod touch run on the iPad models? Can the iPad models run Mac OS X applications?

Applications that can run on the iPhone and iPod touch models -- with the exception of applications that require hardware capabilities that the iPad models lack (such as a "phone" for any iPad or a camera for the original iPad models) -- can run on the iPad either at actual size centered in the middle of the larger iPad screen or "doubled" (which "blows up" each pixel in the iPhone/iPod touch application to twice its size).

Of course, the iPad also can run apps and webapps designed explicitly for the iPad, like EveryMac.com's own EveryMac app for the iPad. A version of the EveryMac app for the iPhone and iPod touch is available, too.

The iPad cannot run Mac OS X applications. Those interested in running Mac OS X on a tablet might be interested in the Axiotron ModBook.

Also see: How does the iPad compare to the Axiotron ModBook? Which one is best for my needs?

Can the iPad run Linux?

Yes. As widely anticipated upon the release of the original iPad, hardworking hackers have managed to run Linux on a "jailbroken" iPad. This hack definitely is not necessary -- or even desirable -- for most users, but for the hacker community, running Linux on anything is a regular rite of passage.