A laptop computer, or simplylaptop(also notebook computer or notebook), is a small mobile computer, which usually weighs 2-18 pounds (1-6 kilograms), depending on size, materials, and other factors.
Laptops usually run on a single main battery or from an external AC/DC adapter which can charge the battery while also supplying power to the computer itself. Many computers also have a 3 volt cell to run the clock and other 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. They contain components that are similar to their desktop counterparts and perform 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. Because of their small size, they incorporate a 20 cm (7 inch) or smaller touch-screen for the user to interact with it (as with a virtual keyboard), though some (such as the OQO Model 02) are designed with a miniature physical keyboard (a thumbboard) and mouse interface. They house lower performing, power-saving components (in comparison to larger laptops). Examples of UMPCs are the OQO Model 02 and the Sony VAIO UX Micro PC.
- Ultraportables
- Laptops with screens typically less than 12 inches diagonally and a weight of less than 3-5 lbs. Their keyboards are usually not full-size. Their primary audience is usually business travelers, who need small, light laptops. Ultraportables are often very expensive, have extended battery life, house power-saving CPUs and almost always have integrated graphics.
- Thin-and-lights
- Laptops usually weighing in between 4-6 lbs with a screen size of between 12 and 14 inches diagonally. Examples of this variety: the Sony VAIO CR , HP Pavilion DV2000,XPS M1210 and XPS M1330,and Apple MacBook .
- Mainstream
- Laptops weighing in between 5 and 7 lbs,with a screen size of 14.1 inches and 15.4 inches.Examples:Dell Inspiron E1405, E1505,1420,1520/1521 and 1501
Related devices
Laptops can be understood as a particular point on the continuum of more or less portable computing devices: the point at which the device is large enough to use substantially the same software as a desktop machine, but small enough to support Mobile computing. Other points on the continuum include:
- Transportables, also called portable computers
- Computers which can easily be moved from place to place, but cannot be used while in transit, usually because they require AC power. The most 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 touchscreen interfaces. As of 2007, the most common subcategory is the Tablet PC, which is essentially a laptop with a touchscreen. Some tablets have no keyboard; others, called "convertibles", have a keyboard which can be folded behind the screen. Tablets may have limited functionality in certain applications that require an actual physical keyboard for typing, but are otherwise capable of carrying out most 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 linux and theyre able to run some applications but they cant replace a computer, Internet tablet feature a MP3,Video, Internet Browser, Chat, and picture viewer
History
Before laptop/notebook computers were technically feasible, similar ideas had been proposed, most notably Alan Kay's Dynabook concept, developed at Xerox PARC in the early 1970s.
The first commercially available portable computer was the Osborne 1 in 1981, which used the CP/M operating system. Although it was large and heavy compared to today's laptops, with a tiny CRT monitor, it had a near-revolutionary impact on business, as professionals were able to take their computer and data with them for the first time. This and other "luggables" were inspired by what was probably the first portable computer, the Xerox NoteTaker, again developed at Xerox PARC, in 1976; however, only ten prototypes were built. The Osborne was about the size of a portable sewing machine, and importantly could be carried on a commercial aircraft. However, it was not possible to run the Osborne on batteries: it had to be plugged into mains.
A more enduring success was the Compaq Portable, the first product from Compaq, introduced in 1983, by which time the IBM Personal Computer had become the standard platform. Although scarcely more portable than the Osborne machines, and also requiring AC power to run, it ran MS-DOS and was the first true IBM clone (IBM's own later Portable Computer, which arrived in 1984, was notably less IBM PC-compatible than the Compaq[citation needed]).
Another significant machine announced in 1981, although first sold widely in 1983, was the Epson HX-20. A simple handheld computer, it featured a full-transit 68-key keyboard, rechargeable nickel-cadmium batteries, a small (120 x 32-pixel) dot-matrix LCD display with 4 lines of text, 20 characters per line text mode, a 24 column dot matrix printer, a Microsoft BASIC interpreter, and 16 KiB of RAM (expandable to 32 KiB).
Disadvantages
Standardization issues
While there are accepted world standards of form factors for all the peripherals and add-in PC cards used in the desktop computers, there are still no firm worldwide standards relating to today's laptops' form factors internally, such as supply of electric voltage, motherboard layouts, internal adapters used in connecting the hard disk, optical drive, LCD cable, keyboard and floppy drive to the main board. Most affected by this are uneducated users, especially if they attempt to connect their laptops with incompatible hardware or power adapters.
Laptops are more complex than simple-to-use consumer electronics. A large number of different parts with similar functions may cause some difficulties to repair technicians, as they have to familiarize themselves with different sets of hardware, but this is part of the job in a specialized trade.
Compatibility issues
Any current compatibility problems in the laptop trade are reflective of the early era of personal computers, when there were many different manufacturers, each and every one of them having their own systems and incompatibility was more a norm.
Some mostly internal or proprietary parts made by laptop producers aren't interchangeable with other manufacturers' products, so that the same manufacturer's components are used with the laptop they produced. Some of the reasons for this are to ensure product stability, prolong product lifetime, to avoid dubious warranty issues and to protect computer beginners from harming their machines.
A significant point to note is that the vast majority of laptops on the market are manufactured by a small handful of ODMs.[3] The ODM matters more than the OEM. Major relationships include:
- Quanta sells to (among others) HP/Compaq, Dell, Toshiba, Sony, Fujitsu, Acer, NEC, Gateway and IBM - note that Quanta is currently (as of August, 2007) the largest manufacturer of notebook computers in the world
- Compal sells to Toshiba, HP/Compaq, Acer, and Dell
- Winstron sells to HP/Compaq, Dell, IBM, NEC, and Acer
- Arima sells to HP/Compaq, NEC, and Dell
- Uniwill/ECS sells to IBM, Fujitsu, and Dell
- Asus sells to Apple (iBook), Sony, and Samsung
- Inventec sells to HP/Compaq, Toshiba, and BenQ
Upgradeability
Laptops' upgradeability is severely limited, both for technical and economic reasons. As of 2006, there is no industry-wide standard form factor for laptops. Each major laptop vendor pursues its own proprietary design and construction, with the result that laptops are difficult to upgrade and exhibit high repair costs. With few exceptions, laptop components can rarely be swapped between laptops of competing manufacturers, or even between laptops from the different product-lines of the same manufacturer. Standard feature peripherals (such as audio, video, USB, 1394, WiFi, Bluetooth) are generally integrated on the main PCB (motherboard), and thus upgrades often require using external ports, card slots, or wireless peripherals. Other components, such as RAM modules, hard drives, and batteries are typically user-upgradeable.
Many laptops have removable CPUs, although support for other CPUs is restricted to the specific models supported by the laptop motherboard. The socketed CPUs are perhaps for the manufacturer's convenience, rather than the end-user, as few manufacturers try new CPUs in last year's laptop model with an eye toward selling upgrades rather than new laptops. In many other laptops, the CPU is soldered and non-replaceable. [7]
Many laptops also include an internal MiniPCI slot, often occupied by a WiFi or Bluetooth card, but as with the CPU, the internal slot is often restricted in the range of cards that can be installed. The widespread adoption of USB mitigates I/O connectivity to a great degree, although the user must carry the USB peripheral as a separate item.
NVidia and ATI have proposed a standardized interface for laptop GPU upgrades (such as an MXM), but again, choices are limited compared to the desktop PCIe/AGP after-market.
On January 2007, Asus announced XG Station external video card for laptops. XG Station is connected to the laptops using USB-2 and Express card interface.
On February 2007, there is a new standard for external PCI Express cable and connector. Future laptops can be expanded using external PCI Express backplane and chassis.
Health issues
A study by State University of New York researchers says heat generated from laptops can significantly elevate the temperature of the scrotum, potentially putting sperm count at risk. The study, which included more than two dozen men ages 13 to 35, found that the sitting position required to balance a laptop can raise scrotum temperature by as much as 2.1°C. Heat from the laptop itself can raise the temperature by another 0.7°C, bringing the potential total increase to 2.8°C. However, further research is needed to determine whether this directly affects sterility in men. [8]
Security
Laptops are generally prized targets of theft, and theft of laptops can lead to more serious problems such as identity theft from stolen credit card numbers.[9] Most laptops have a Kensington security slot to chain the computer to a desk with a third party security cable. In addition to this, modern operating systems and software may have disk encryption functionality that renders the data on the laptop's hard drive unreadable without a key, providing the laptop was not turned on while stolen.
