iPad

The iPad (pronounced /ˈaɪpæd/ eye-pad) is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple’s then-CEO Steve Jobs. Its size and weight fall between those of contemporary smartphones and laptop computers. The iPad runs the same operating system as the iPod Touch and iPhone—and can run its own applications as well as iPhone applications. Without modification, the iPad will only run programs approved by Apple and distributed via the Apple App Store (with the exception of programs that run inside the iPad’s web browser).

Like iPhone and iPod Touch, the iPad is controlled by a multitouch display—a departure from most previous tablet computers, which used a pressure-triggered stylus—as well as a virtual onscreen keyboard in lieu of a physical keyboard. The iPad uses a Wi-Fi connection to access local area networks and the Internet. Some models also have a 3G wireless network interface which can connect to HSPA or EV-DO data networks and on to the Internet. The device is managed and synced by iTunes running on a personal computer via USB cable.

Apple released the first iPad in April 2010, and sold 3 million of the devices in 80 days. During 2010, Apple sold 14.8 million iPads worldwide, representing 75 percent of tablet PC sales at the end of 2010.

By the release of the iPad 2 in March 2011, more than 15 million iPads had been sold – selling more than all other tablet PCs combined since the iPad’s release. In 2011, it is expected to take 83 percent of the tablet computing market share in the United States.

Screen and input

The iPad’s touchscreen display is a 1024 × 768 pixel, 7.75×5.82 in (197×148 mm) liquid crystal display (diagonal 9.7 in (246.4 mm)), with fingerprint- and scratch-resistant glass. Steve Jobs backed the choice of screen size, saying a 7-inch screen would be “too small to express the software” and that 10 inches was the minimum for a tablet screen.Like the iPhone, the iPad is designed to be controlled by bare fingers; normal, non-conductive gloves and styli do not work, although there are special gloves and capacitive styli designed for this use.

The display responds to other sensors: an ambient light sensor to adjust screen brightness and a 3-axis accelerometer to sense iPad orientation and switch between portrait and landscape modes. Unlike the iPhone and iPod Touch’s built-in applications, which work in three orientations (portrait, landscape-left and landscape-right), the iPad’s built-in applications support screen rotation in all four orientations, including upside-down. Consequently, the device has no intrinsic “native” orientation; only the relative position of the home button changes.

There are four physical switches on the iPad, including a home button near the display that returns the user to the main menu, and three plastic physical switches on the sides: wake/sleep and volume up/down, plus a software-controlled switch whose function has changed with software updates. Originally the switch locked the screen to its current orientation, but the iOS 4.2 changed it to a mute switch, with rotation lock now available in an onscreen menu. In the iOS 4.3 update, released with the iPad 2, a setting was added to allow the user to specify whether the side switch was used for rotation lock or mute.

The original iPad had no camera; the iPad 2 has a front VGA camera and a rear-facing 720p camera, both capable of still images and 30fps video. The rear-facing camera has a 5x digital zoom for still images only. Both shoot photo and video in a 4:3 fullscreen aspect ratio, unlike the iPhone 4, which shoots in a 16:9 widescreen aspect ratio. Unlike the iPhone, the iPad does not support tap to focus. The cameras allow FaceTime video messaging with iPhone 4, iPod Touch 4, and Snow Leopard/Lion Macs.

Connectivity

The iPad can use Wi-Fi network trilateration from Skyhook Wireless to provide location information to applications such as Google Maps. The 3G model supports A-GPS to allow its position to be calculated with GPS or relative to nearby cellphone towers; it also has a black strip on the back to aid 3G reception.

The iPad has a headphone jack and a proprietary Apple dock connector, but no Ethernet or USB port.

Audio and output

The iPad has two internal mono speakers located on the bottom-right of the unit. In the original iPad, the speakers push sound through two small sealed channels leading to the three audio ports carved into the device, while the iPad 2 has its speakers behind a single grill.

A volume switch is on the right side of the unit. A 3.5-mm TRRS connector audio-out jack on the top-left corner of the device provides stereo sound for headphones with or without microphones and/or volume controls. The iPad also contains a microphone that can be used for voice recording.

The built-in Bluetooth 2.1 + EDR interface allows wireless headphones and keyboards to be used with the iPad. However, the iOS does not currently support file transfer via Bluetooth.[64] iPad also features 1024 x 768 VGA video output for limited applications, screen capture, connecting an external display or television through an accessory adapter.

Software

Like the iPhone, with which it shares a development environment (iPhone SDK, or software development kit, version 3.2 onwards), the iPad only runs its own software, software downloaded from Apple’s App Store, and software written by developers who have paid for a developer’s license on registered devices. The iPad runs almost all third-party iPhone applications, displaying them at iPhone size or enlarging them to fill the iPad’s screen. Developers may also create or modify apps to take advantage of the iPad’s features. Application developers use iPhone SDK for developing applications for iPad. The iPad has been shipping with a customized iPad-only version of iPhone OS, dubbed v3.2. On September 1, it was announced the iPad would get iOS 4.2 by November 2010. Apple released iOS 4.2.1 to the public on November 22.

Source: http://en.wikipedia.org/wiki/IPad