วันจันทร์ที่ 20 ธันวาคม พ.ศ. 2553

Laptop

Laptop

A laptop (also known as a notebook)[1][2] is a personal computer designed for mobile use.[3][4][5] A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device (a touchpad, also known as a trackpad, and/or a pointing stick) and speakers into a single unit. A laptop is powered by mains electricity via an AC adapter, and can be used away from an outlet using a rechargeable battery. A laptop battery in new condition typically stores enough energy to run the laptop for three to five hours, depending on the computer usage, configuration and power management settings. When the laptop is plugged into the mains, the battery charges, whether or not the computer is running, with the exception of some laptops.
Portable computers, originally monochrome CRT-based and developing into the modern laptop, were originally considered to be a small niche market, mostly for specialized field applications such as the military, accountants and sales representatives. As portable computers became smaller, lighter, and cheaper and as screens became larger and of better quality, laptops became very widely used for all purposes.









Desktop replacement

A desktop-replacement computer is a laptop that provides most of the capabilities of a desktop computer, with a similar level of performance. Desktop replacements are usually larger and heavier than standard laptops. They contain more powerful components and have a 15" or larger display.[16] They are bulkier and not as portable as other laptops, and their operation time on batteries is typically shorter; they are intended to be used as compact and transportable alternatives to a desktop computer.[16]
Some laptops in this class use a limited range of desktop components to provide better performance for the same price at the expense of battery life; a few of those models have no battery. These, and sometimes desktop-replacement computers in general, are sometimes called desknotes, a portmanteau of "desktop" and "notebook".[17]
In the early 2000s desktops were more powerful, easier to upgrade, and much cheaper than laptops, but in later years laptops have become much cheaper and more powerful,[18] and most peripherals are available in laptop-compatible USB versions which minimise the need for internal add-on cards. In the second half of 2008 laptops outsold desktops for the first time.
The names "Media Center Laptops" and "Gaming Laptops" are used to describe specialized notebook computers.
[15]







Subnotebook

A subnotebook or ultraportable, is a laptop designed and marketed with an emphasis on portability (small size, low weight and often longer battery life) that retains performance close to that of a standard notebook.[19] Subnotebooks are usually smaller and lighter than standard laptops, weighing between 0.8 and 2 kg (2 to 5 pounds);[15] the battery life can exceed 10 hours[20] when a large battery or an additional battery pack is installed. Since the introduction of netbooks, the line between subnotebooks and higher-end netbooks has been substantially blurred.
To achieve the size and weight reductions, ultraportables use 13" and smaller screens (down to 6.4"), have relatively few
ports (but in any case include two or more USB ports), employ expensive components designed for minimal size and best power efficiency, and utilize advanced materials and construction methods. Most subnotebooks achieve a further portability improvement by omitting an optical/removable media drive; in this case they may be paired with a docking station that contains the drive and optionally more ports or an additional battery.
The term "subnotebook" is reserved to laptops that run general-purpose desktop operating systems such as
Windows, Linux or Mac OS X, rather than specialized software such as Windows CE, Palm OS or Internet Tablet OS.



Netbook and netp
Netbooks are laptops that are light-weight, economical, energy-efficient and especially suited for wireless communication and Internet access.[21][22] Hence the name netbook (as "the device excels in web-based computing performance")[23] rather than notebook which pertains to size.[24]
With primary focus given to web browsing and e-mailing, netbooks are intended to "rely heavily on the Internet for remote access to web-based applications"[23] and are targeted increasingly at cloud computing users who rely on servers and require a less powerful client computer.[25] While the devices range in size from below 5 inches[26] to over 12,[27] most are between 9 and 11 inches (280 mm) and weigh between 0.9 – 1.4 kg (2–3 pounds).[23]
Netbooks are mostly sold with light-weight operating systems such Linux, Windows XP and Windows 7 Starter edition.
A netpad is a laptop which is heavily built on RAM specifications to take on
internet surfing.




Tablet laptop

A Lenovo X61 tablet laptop with stylus
Typical modern
convertible laptops have a complex joint between the keyboard housing and the display permitting the display panel to swivel and then lie flat on the keyboard housing.
Typically, the base of a tablet laptop attaches to the display at a single joint called a swivel hinge or rotating hinge. The joint allows the screen to rotate through 180° and fold down on top of the keyboard to provide a flat writing surface. This design, although the most common, creates a physical point of weakness on the notebook.
Some manufacturers have attempted to overcome these weak points. The
Panasonic Toughbook 19, for example, is advertised as a more durable convertible notebook. One model by Acer (the TravelMate C210) has a sliding design in which the screen slides up from the slate-like position and locks into place to provide the laptop mode.
Tablet laptops have the advantage to offer the keyboard and pointing device (usually a trackpad) of older notebooks, for users who do not use the
touchscreen display as the primary method of input.







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