iOS 4.2 is compatible with all existing iOS devices except the original iPhone and first-generation iPod touch. However, some features (such as multitasking) won’t work on older devices, including the iPhone 3G and the second-generation iPod touch.
Once the update is released, users of compatible devices can update by attaching a device to a Mac or PC, selecting it in the iTunes source list, and clicking the Check For Update button. (It’s always a wise idea to let iTunes back up your device before running an iOS update, in case there’s an error that forces you to erase it.
Despite the presence of AirTunes and AirPrint, the big story of iOS 4.2 is really that it brings the features of iOS 4 to the iPad for the first time. After the release today, the iPad and iPhone will be running the same version of iOS for the very first time.
iOS 4’s multitasking features are very nice on the iPhone, but they’re a revelation on the iPad. With this one free software update, all existing iPads get a huge productivity boost. When we talk iOS multitasking, it’s important to note that we’re actually talking about several different features: the ability for apps to run portions of themselves in the background while other apps are in the foreground, the ability for apps to pick off right where you left them when you switch back to them, and the new “fast app switcher” interface that appears when you double-tap the home button.
When you put these three features together, you get multitasking, iOS 4 style. And on the iPad, which is generally populated by more complex apps than the iPhone,
it really shines. In my testing, I was able to flip quickly between Mail, a Twitter client, and a text editor. Double-tapping the home button and using the fast app switcher quickly became a habit, and because iOS 4-savvy apps pick up right where you left off, switching into an app no longer becomes a speed bump that requires you to navigate back to where you were before. You can get in a real groove once you get the hang of it. It’s not quite the same as running several programs on a Mac or PC—you are, after all, only running one app in the foreground at a time—but it’s a much more productive environment than prior to the OS 4.2 update.
OS 4.2’s fast app switcher also contains another small productivity boost: a quick swipe from left to right brings up a control panel featuring a brightness slider, so you can adjust screen brightness without launching the Settings app. There’s also an orientation-lock button, because with this release Apple has changed the behavior of the switch just above the iPad’s hardware volume buttons. Previously, that switch locked the iPad’s orientation, so you could hold the iPad in odd positions without the contents of the screen automatically rotating. Now that switch is a mute switch, which silences notifications (but not all noise) coming from the iPad.
Another big productivity boost for iPad users in iOS 4.2 comes from the Mail application’s new unified inbox. If you find yourself using more than one account (for example, one for personal mail, another for work mail), you’re probably familiar with the four taps that are required in order to switch from one inbox to another. With iOS 4.2, Apple’s reduced that to no taps—there’s a unified view that stitches all inboxes together. (If you would rather keep your e-mail lives separate, you can still do that, too.)
In addition, conversations in iPad mail are now threaded. No longer will you reply to a message only to discover that an hour later someone else responded with the same answer—now all messages in a reply chain will appear grouped together in a submenu of the mailbox in question.
Also, the ability to set up multiple Microsoft Exchange ActiveSync accounts means that iPad users can now wirelessly sync both a work calendar running on an Exchange server and a personal Google calendar, for example.
And the addition of folders to the iPad's home screen means the iPad can now hold a ridiculous number of apps—and more importantly, users can now organize their apps better and across fewer pages of the home screen.
Take a look here if you want to use airprint with your printer: www.tuaw.com/2010/11/11/airprint-how-to-m