Figuring out your touch input requires the cooperation of the iPod touch's processor, operating system, hardware and software.

iPod touch Processor and Interface

The iPod touch's processor keeps track of where you put your fingers and where they move once you've placed them on the screen. You can slide your fingers from place to place, or you can make pinching or spreading motions to zoom in and out. The iPod touch matches what your fingers are doing with what's happening on the screen:

  • The iPod touch determines the shape, size and location of your finger -- or fingers -- on the screen.
  • The device uses gesture software in its memory to classify your touch. It takes into account whether your fingers move and what your iPod is doing at the time.
  • The processor sends instructions to the iPod touch's display, software and hardware based on the data your fingers create.

Here's an example. If you're using the Safari Web browser and you want to type in a URL, you touch the URL field in the browser. The capacitive layer detects your touch on the screen, and the processor and gesture software cross-reference the touch data with the application in use. The processor relays a message to the iPod touch's screen, telling it to display an image of a keyboard. The screen then detects the location of each virtual key you touch, and the screen displays the corresponding letter in the URL field. Each time you touch the screen, the process of determining what you're touching and why happens in the background, almost instantaneously.

The gestures themselves are fairly intuitive. To turn the iPod touch on, you press the home or sleep/wake button, then move your finger across the slider that appears on the screen. To press on-screen buttons, you simply touch them. You can scroll through lists of files by sweeping your finger up and down the screen. If you turn the iPod touch horizontally, you can browse music through CoverFlow, an animated display of your music's cover art. As with the iPhone, you can zoom in to pictures and Web pages by using two fingers and spreading them apart, as if stretching to make the picture bigger. To zoom out again, pinch your fingers together, as if trying to shrink the picture.

The latest iPod touch models have two cameras, one on the front and one on the back. They can make Facetime video calls to other current iPod touch devices, iPhone 4 handsets and Macintosh computers running Mac OS X 10.6.4 or later. The camera also gives you the chance to capture and edit HD video using your iPod touch. The mp3 player now has a retina display with four times more pixels on the screen than previous iPod touch models [source: Apple].

The iPod touch grew in popularity in its first three years, and it came close to outselling the iPhone in late 2009. The Apple iPad, introduced in early 2010, does most everything the iPod touch can do, but on a larger device with more features. Besides being able to run almost all the App Store apps, the iPad has special iBooks software so it can be an e-reader (like the Amazon Kindle). It also has an optional keyboard dock with a full-size keyboard. With the new features comes a much higher price: The iPad starts at $499 for a 16 GB model with WiFi, and the prices go as high as $829 for a 64 GB model with both WiFi and 3G. Time will tell whether the iPod touch can keep up its popularity as its bigger sibling hits the market.

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