07-12-2012, 06:43 PM
Google Chrome OS
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INTRODUCTION
Google Chrome OS is a Linux-based operating system designed by Google to work exclusively with web applications. Google announced the operating system on July 7, 2009 and made it an open source project, called Chromium OS, in November.[3][4]
Unlike Chromium OS, which can be compiled from the downloaded source code, Chrome OS only ships on specific hardware from Google's manufacturing partners.[5] The user interface takes a minimalist approach, resembling that of the Google Chrome web browser. Since Google Chrome OS is aimed at users who spend most of their computer time on the Web, the only application on the device is a browser incorporating a media player and a file manager.[4][6][7][8][9]
The launch date for retail hardware featuring Chrome OS slipped after Google first announced the operating system: from an initial forecast date in late 2010 to June 15, 2011, when "Chromebooks" from Samsung (and then Acer in July) actually shipped.
History
Google developers began coding the operating system in 2009, inspired by the growing popularity and lower power consumption ofnetbooks and the focus of these small laptops on Internet access. To ascertain marketing requirements for an operating system focused on netbook Web transactions, the company did not do the usual demographic research generally associated with a large software development project. Instead, engineers relied on more informal metrics, including monitoring the usage patterns of some 200 Chrome OS machines used by Google employees. Developers also noted their own usage patterns. Matthew Papakipos, former[15] engineering director for the Chrome OS project, put three machines in his house and found himself logging in for brief sessions: to make a single search query or send a short email.[6]
On November 19, 2009, Google released Chrome OS's source code as the Chromium OS project.[4] As with other open source projects, developers are modifying code from Chromium OS and building their own versions, whereas Google Chrome OS code will only be supported by Google and its partners, and will only run on hardware designed for the purpose. Unlike Chromium OS, Chrome OS will be automatically updated to the latest version.[16] InformationWeek reviewer Serdar Yegulalp wrote that Chrome OS will be a product, developed to "a level of polish and a degree of integration with its host hardware that Chromium OS does not have by default," whereas Chromium OS is a project, "a common baseline from which the finished work is derived" as well as a pool for derivative works. The product and project will be developed in parallel and borrow from each other.[17]
At a November 19, 2009 news conference, Sundar Pichai, the Google vice president overseeing Chrome, demonstrated an early version of the operating system. He previewed a desktop which looked very similar to the Chrome browser, and in addition to the regular browser tabs also had application tabs, which take less space and can be pinned for easier access. At the conference, the operating systembooted up in seven seconds, a time Google said it would work to reduce.
Commercial hardware: Chromebooks
Google initially named several development partners working on hardware for the operating system, with others named in the press, including Acer, Adobe, Asus, Freescale, Hewlett-Packard, Lenovo, Qualcomm, Texas Instruments, Toshiba,[38] Intel,[39] Samsung,[40][41]and Dell.[42]
On May 11, 2011 at its Google I/O developer conference, Google announced that the first two commercially available laptops incorporating Chrome OS would be manufactured by Acer Inc. and Samsung Electronics Co., with a retail price beginning at $349. The ship date was June 15 for the United States, the United Kingdom, France, Germany, Netherlands, Italy and Spain. The Chromebooks are sold in the United States through Amazon and Best Buy; internationally through "leading retailers". Google claimed an eight-second bootup time and eight-hour operation on one battery charge, and said that the chromebooks would require no virus protection. Models equipped with 3G connectivity receive 100 megabytes of wireless data per month, free for two years, with an additional gigabyte at $20 per month. Google is also working on a Chrome OS desktop machine.
New window manager and graphics engine
On April 10, 2012, a new build of Chrome OS offered a choice between the original full-screen window interface and overlapping, re-sizable windows, such as found on Microsoft Windows and Apple's Mac OS X. The feature was implemented through the Ash window manager, which runs atop the Aura hardware-accelerated graphics engine. The April 2012 upgrade also included the ability to display smaller, overlapping browser windows, each with its own translucent tabs, browser tabs that can be "torn" and dragged to new positions or merged with another tab strip, and a mouse-enabled shortcut list across the bottom of the screen. One icon on the task bar shows a list of installed apps and bookmarks. Writing in CNET, Stephen Shankland argued that with overlapping windows, "Google is anchoring itself into the past" as both iOS and Microsoft's Metro interface are largely or entirely full-screen. Even so, "Chrome OS already is different enough that it's best to preserve any familiarity that can be preserved".
Architecture
In preliminary design documents for the Chromium OS open source project, Google described a three-tier architecture: firmware, browser and window manager, and system-level software and userland services.[56]
The firmware contributes to fast boot time by not probing for hardware, such as floppy disk drives, that are no longer common on computers, especially netbooks. The firmware also contributes to security by verifying each step in the boot process and incorporating system recovery.[56]
System-level software includes the Linux kernel that has been patched to improve boot performance. Userland software has been trimmed to essentials, with management by Upstart, which can launch services in parallel, re-spawn crashed jobs, and defer services in the interest of faster booting.[56]
The window manager handles user interaction with multiple client windows much like other X window managers