Sunday, May 31, 2009

iPHONE

The iPhone is an internet-connected multimedia smartphone designed and marketed by Apple Inc. Since its minimal hardware interface lacks a physical keyboard, the multi-touch screen renders a virtual keyboard when necessary. The iPhone functions as a camera phone (also including text messaging and visual voicemail), a portable media player (equivalent to an iPod), and an Internet client (with email, web browsing, and local Wi-Fi connectivity). The first-generation phone hardware was quad-band GSM with EDGE; the second generation added UMTS with HSDPA.

Apple announced the iPhone on January 9, 2007, after months of rumors and speculation. The iPhone was introduced in the United States on June 29, 2007 before being marketed worldwide. Time magazine named it the Invention of the Year in 2007. Released July 11, 2008, the iPhone 3G supports faster 3G data speeds and assisted GPS. On March 17, 2009, Apple announced the iPhone firmware version 3.0, due to be released in mid 2009. The touchscreen is a 9 cm (3.5 in) liquid crystal display (320×480 px at 6.3 px/mm, 160 ppi, HVGA) with scratch-resistant glass, and can render 262,144 colors. The capacitive touchscreen is designed for a bare finger, or multiple fingers for multi-touch sensing. Most gloves and styluses prevent the necessary electrical conductivity.

The display responds to three sensors. A proximity sensor deactivates the display and touchscreen when the iPhone is brought near the face during a call. This is done to save battery power and to prevent inadvertent inputs from the user's face and ears. An ambient light sensor adjusts the display brightness which in turn saves battery power. A 3-axis accelerometer senses the orientation of the phone and changes the screen accordingly, allowing the user to easily switch between portrait and landscape mode. Photo browsing, web browsing, and music playing support both upright and left or right widescreen orientationsLater, a software update allowed the first generation iPhone to use cell towers and Wi-Fi networks for location finding despite lacking a hardware GPS. The iPhone 3G supplements those methods with A-GPS.

The iPhone has three physical switches on the sides: wake/sleep, volume up/down, and ringer on/off. These are made of plastic on the original iPhone and metal on the iPhone 3G. A single "home" hardware button below the display brings up the main menu. The touch screen furnishes the remainder of the user interface. The back of the original iPhone was made of aluminum with a black plastic accent. The iPhone 3G features a full plastic back to increase GSM signal strength The plastic is black for the 8 GB model, but the 16 GB version is also available in white.

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