Laptop
From Wikipedia, the free encyclopedia
A laptop computer, or simply laptop (also notebook computer or notebook), is a small mobile computer, which usually weighs 2-18 pounds (around 1 to 8 kilograms), depending on size, materials, and other factors.
Laptops usually run on a single main battery or from an external AC/DC adapterwhich can charge the battery while also supplying power to the computeritself. Many computers also have a 3 volt cell to run the clock andother processes in the event of a power failure. 
As Personal computers, laptops are capable of the same tasks as a desktop computer,although they are typically less powerful for the same price. Theycontain components that are similar to their desktop counterparts andperform the same functions, but are miniaturized and optimized for mobile use and efficient power consumption. Laptops usually have liquid crystal displays and most of them use different memory modules for their random access memory (RAM), for instance, SO-DIMM in lieu of the larger DIMMs. In addition to a built-in keyboard, they may utilize a touchpad (also known as a trackpad) or a pointing stick for input, though an external keyboard or mouse can usually be attached.
Categories
Terms sometimes used for subtypes of laptop computers include:
- UMPCs
- These Ultra-Mobile PCs are mobile computers with a size comparable to PDAs- they are extremely portable. They are now officially called notebooksas the term lap- top insinuated the laptop should be used on the lap,this however caused the hard drive to over heat thus in turn canseriously damage the computer. Because of their small size, theyincorporate a 20 cm (7 inch) or smaller touch-screen for the user tointeract with it (as with a virtual keyboard), though some are designed with a miniature physical keyboard (a thumbboard) and mouse interface. They house lower performing, power-saving components (in comparison to larger laptops).
- Ultraportables
- Laptops with screens typically less than 12 inches (30 cm)diagonally and a weight of less than 3 to 5 lb (1.4–2.3 kg). Theirkeyboards are usually not full-size. Their primary audience is usuallybusiness travelers, who need small, light laptops. Ultraportables areoften very expensive, have extended battery life, house power-saving CPUs and almost always have integrated graphics.
- Thin-and-lights
- Laptops usually weighing in between 4 and 6 lb (1.8–2.7 kg) with ascreen size of between 12 and 14 inches (30–35 cm) diagonally.
- Mainstream
- Laptops weighing in between 5 and 7 lb (2.3–3.2 kg), with a screen size of 14.1 inches and 15.4 inches (35 and 39 cm).
- Desktop replacement computers
- Powerful laptops meant to be mainly used in a fixed location andinfrequently carried out due to their weight and size; the latterprovides more space for powerful components and a big screen, usuallymeasuring 17–20 inches (43–51 cm). Desktop replacements tend to havelimited battery life, rarely exceeding three hours, because thehardware is not optimized for efficient power usage. Sometimes called aluggablelaptop. An example of a desktop replacement computers are gamingnotebooks, which are designed to handle 3D graphic-intensive processingfor gamers.
Related devices
Laptops can be understood as a particular point on the continuum ofmore or less portable computing devices: the point at which the deviceis large enough to use substantially the same software as a desktopmachine, but small enough to support mobile computing. Other points on the continuum include:
- Transportable, also called portable computers
- Computers which can easily be moved from place to place, but cannotbe used while in transit, usually because they require AC power. Themost famous example is the Osborne 1. A transportable, like a laptop, can run desktop software; but it does not support mobile computing.
- Tablets
- Computers shaped like slates or (paper) notebooks, with touchscreeninterfaces include a magnetized stylus and software for allowing inputto be recognized by the touch screen. As of 2007, the most commonsubcategory is the Tablet PC,which is essentially a laptop with a touchscreen. Some tablets have nokeyboard; others, called "convertibles", have a screen which can berotated 180 degrees and folded on top of the keyboard. Tablets may havelimited functionality in certain applications that require an actualphysical keyboard for typing, but are otherwise capable of carrying outmost tasks that an ordinary laptop would be able to perform.
- Internet tablets
- Internet appliances in tablet form. An internet tablet supports mobile computing. Internet tablets usually use Linuxand they are able to run some applications, but they cant replace acomputer. Internet tablets feature MP3, video, internet browser, chat,and picture viewer.
- Personal digital assistants (PDAs)
- Small computers, usually pocket-sized, usually with limitedfunctionality. A PDA supports mobile computing, but almost never runsany desktop software.
- Handheld computers
- A high-end PDA or small tablet.
- Smart phone
- A hand held or PDA with an integrated cellphone.
Boundaries that separate these categories are blurry at times. For example, the OQO UPC is a PDA-sized tablet PC; the Apple eMate had the clamshell form factor of a laptop, but ran PDA software. The HP Omnibook line of laptops included some devices small enough to be called handheld computers. The hardware of the Nokia 770 internet tablet is essentially the same as that of a PDA such as the Zaurus 6000; the only reason it's not called a PDA is that it doesn't have PIM software. On the other hand, both the 770 and the Zaurus can run some desktop Linux software, usually with modifications.
