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A laptop computer (also known as notebook computer) is a small mobile personal computer, usually weighing from 1 to 3 kilograms (2 to 7 pounds). Terms for subtypes of notebooks (and related computer types) include:

Notebooks smaller than an A4 sheet of paper and weighing around 1 kg are sometimes called sub-notebooks or subnotebooks.
Notebooks weighing around 5 kg are sometimes termed desknotes (desktop/notebook).
Powerful laptops (often heavy) designed to compete with the computing power offered by a typical desktop are sometimes known as desktop replacements.
Computers larger than PDAs but smaller than notebooks are also sometimes called palmtops.

Laptops usually run on batteries, but also from adapters which also charge the battery using mains electricity.

Laptops are capable of many of the same tasks that desktop computers perform, although they are typically less powerful for the same price. Laptops contain components that are similar to those in 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 use SO-DIMM (Small Outline DIMM) modules (rather than the larger DIMMs used in desktop computers)for their RAM. 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 mouse or keyboard can usually be attached.

History

Before laptop 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 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 in.

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-compatible than the Compaq.)

However, the first true laptop was the GRiD Compass 1101, designed by William Moggridge in 1979, and released in 1982. Enclosed in a magnesium case, it introduced the now familiar clamshell design, in which the flat display folded shut against the keyboard. The computer could be run from batteries, and was equipped with a 320×200-pixel plasma display and 384-kilobyte bubble memory. It was not IBM-compatible, and its high price (US$ 10,000) meant that it was limited to specialized applications. However, it was used heavily by the U.S. military, and was used on the Space Shuttle during the 1980s. The GRiD company subsequently earned significant returns on its patent rights as its innovations became commonplace. GRiD Sytems Corp was later bought by Tandy (RadioShack).

Two other noteworthy early laptops were the Sharp PC-5000 (1983) and the Gavilan computer, announced in 1983 but first sold in 1984. The Gavilan was notably the first computer to be marketed as a "laptop." It was also equipped with a pioneering touchpad-like pointing device, installed on a panel above the keyboard. Like the GriD Compass, the Gavilan and the Sharp were housed in clamshell cases, but they were partly IBM-compatible, although primarily running their own system software. Both had LCD displays, and had optional printers that attached to their cases.

1983 also saw the launch of what was probably the biggest-selling early laptop, the Kyocera Kyotronic 85. Although it was at first a slow seller in Japan, it was quickly licensed by Tandy Corporation, Olivetti, and NEC, who saw its potential and marketed it as the Olivetti M-10, NEC PC-8201, and [1] Radio Shack TRS-80 Model 100 or Tandy 100. The machines ran on standard AA batteries. The Tandy's internal programs, including a BASIC interpreter, a text editor, and a terminal program, were supplied by Microsoft, and are thought to have been written in part by Bill Gates himself. The computer was not a clamshell, but provided a tiltable 8×40-character LCD screen above a full-travel keyboard. With its internal modem, it was a highly portable communications terminal. Due to its portability, good battery life (and ease of replacement), reliability (it had no moving parts), and low price (as little as US $300), the model was highly regarded, becoming a favorite among journalists. It weighed less than 2 kg (4 lb) with dimensions of 30 x 21.5 x 4.5 cm (12 x 8.5 x 1.75 inches). Initial specs included 8 kb of RAM (expandalbe to 24 kb) and a 3 MHz processor.

Among the first commercial IBM-compatible laptops were the IBM PC Convertible, introduced 1986, and the Toshiba T1000 and T1200, introduced 1987. Although limited floppy-based DOS machines (the operating system was stored in ROM), the Toshiba machines were small and light enough to be carried in a backpack, and could be run off lead-acid batteries. These also introduced the now-standard "resume" feature to DOS-based machines; the computer could be paused between sessions, without having to be restarted each time.

Another notable computer was the Cambridge Z88, designed by Clive Sinclair, introduced in 1988. About the size of an A4 sheet of paper, it ran on standard batteries, and contained basic spreadsheet, word processing, and communications programs. Although it anticipated the future miniaturization of the portable computer, as a ROM-based machine with a small display it can — like the TRS-80 Model 100 — also be seen as a foreruner of the PDA.

By the end of the 1980s, laptop computers were becoming popular among businesspeople. The NEC Ultralite, released in mid-1989, was perhaps the first notebook computer, weighing just over 2 kg; in lieu of a floppy or hard drive, it contained a 2-megabyte RAM drive, but this reduced its utility as well as its size. The first notebook computers with standard drives were the Compaq LTE series, introduced toward the end of that year. Truly the size of a notebook, they had hard drives and standard-resolution screens.

The first Apple Computer machine designed to be used on the go was the 1989 Macintosh Portable (although an LCD screen had been an option for the transportable Apple IIc in 1984). Another "luggable," rather than laptop, the Mac Portable was praised for its clear active matrix display and long battery life, but was a poor seller due to its bulk. In the absence of a true Apple laptop, several compatible machines such as the Outbound Laptop were available for Mac users; however, for copyright reasons, the user had to supply a set of Mac ROMs, which usually meant having to buy a new or used Macintosh as well.

The Apple PowerBook series, introduced in 1991, heralded many changes that are now standard on laptops, including ergonomic improvements such as the placement of the keyboard at the back of the machine, thus creating a palm rest, and the inclusion of a built-in pointing device (a trackball). The following year, IBM released its Thinkpad series, offering similar miniaturization.

Later PowerBooks introduced the first 256-color displays, first true touchpad, and first built-in Ethernet networking.

Parts

Many parts for a laptop computer are smaller, lighter, or otherwise adapted from the corresponding part in a desktop computer:

Most modern laptops use an active matrix display with resolutions of 1024 by 768 pixels (XGA) and above, screen sizes 10 inch (250 mm) or larger, and have a PC-Card expansion bay for expansion cards, formerly called PCMCIA. Internal hard disks are smaller—2.5 inch (64 mm) compared to the standard desktop 3.5 inch (90 mm) drive—and usually have lower performance and power consumption. Display adapters and sound cards are integrated. Modern laptops can often handle sophisticated games, but tend to be limited by their fixed screen resolution and display adapter type.
Notebook processor There are a wide range of notebook processors available from Intel (Pentium M (with Centrino technology), Celeron, Mobile Pentium 4 and Mobile Pentium 4-M), AMD (Athlon, Turion 64) which develops and manufactures for the different Microsoft operating systems. Motorola and IBM develops and manufactures the PowerPC chips for Apple notebooks. Generally, notebook processors are less powerful than their desktop counterparts, owing to the need to conserve electricity and reduce heat output. However, the PowerPC G3 and G4 processor generations have been able to offer almost the same performance as their desktop versions, limited mostly by lower performance in other parts of the system bus bandwidth and peripheral units) in Apple's notebooks.

Some parts for a modern laptop have no corresponding part in a desktop computer:

Current models use lithium ion batteries, which have largely replaced the older nickel metal-hydride technology. Typical battery life for most laptops is two to five hours with light-duty use, but may drop to as little as one hour with intensive use. Batteries gradually degrade over time and eventually need to be replaced, depending largely on the charging and discharging pattern, from one to five years.
Docking stations may be used for expanding connectors and quickly connecting many components to the laptop, although they are falling out of favour as laptops' integral capabilities increase and USB allows several peripherals to be connected through one plug.
Most laptops are powered or recharged from an external AC converter that usually takes the form of a plain black rectangular box. These devices weigh about 500 g (about 1 lb) and often take the name "power brick." Apple laptops have a lighter, white and more stylish, charging device.

Upgradability

Laptops generally cost more than a desktop computer of similar specification. Performance is usually lower than that of a comparable desktop because of the compromises necessary to keep weight and power consumption low.

Upgradability is severely limited: typically only the RAM and hard drive can be upgraded. Often the CPU can also be replaced, and sometimes video card modules are upgradable too. Many laptops also include a MiniPCI slot inside, however it is usually not intended to be utilized by the end user. Because nearly all functions are integrated into the proprietary-design mainboard theoretically to save space and power, laptops are difficult to repair and upgrade. Outright replacement of faulty parts can include the display screen, drives, daughterboards, modem, storage devices and other components, but repair costs can be high, even when feasible (low upgradability). There is not a standard for A4-size laptops.

Performance

However, newer types of laptops now rival desktops. These desknotes or desktop replacements are the result of the development of more powerful batteries, and the practice of installing desktop components directly into desknotes, making them equivalent in performance with desktops of similar specifications, albeit much larger than their laptop predecessors. As a result desknotes are generally too bulky to carry around, and most people who use these computers at their place of work will tend to carry them around less frequently.

The relative difference in performance between desktops and desknotes has therfore gradually decreased as developers continually attempt to upgrade the performance of desknotes.

However, while laptops continue to provide the mobility which desknotes may not possess, sales of standard laptops have remained high regardless of the extra performance desknotes provide.

Some companies who market "laptops" with the full power of a desktop, or even a server, often misrepresent what the concept of a laptop encompasses. For example, Vertegri of Canada once sold full Macintosh clone machines in a large laptop case, with no battery; and Tadpole Computers line of SPARC laptops have everything from dual processors to full-size PCI slots, but some models again have no battery. These machines are closer to the Transportables of an earlier time, but use a standard laptop form factor.

Ultralight

A further category of ultra-light laptops has recently been developed, which emphasizes the small, light profile of the genre (screen size of 12 inch diagonal or less), while packing as much performance as possible into the package. These are called sub-notebooks or palmtops and almost all can only have RAM or hard drive upgrades. These also tend to have relatively small hard drives (e.g. 40 gigabytes or less as of 2005).

Misconceptions about laptops

Ironically, despite their name, using a laptop on one's lap can be both unpleasant (due to heat from the computer, particularly from its CPU) and possibly even dangerous to the laptop (it may overheat). It is best to always use a laptop on a desk.

The word laptop is often spelled incorrectly, e.g. labtop, lab top, and lap top. It is uncertain whether most users of the "labtop" spelling realize that this is incorrect.

Anecdotal evidence suggests that many computer illiterates and novice computer users do not realize that a "laptop" is, in fact, a type of "computer". It is possible to hear people making statements such as "That file isn't on the laptop, it's on the computer" (i.e. "it's on the desktop"). (This ties in with a larger trend of novices misunderstanding or misusing common computer terms, such as the common use of "hard drive" to refer to a computer "box".)

Additionally, one Wikipedia editor reports having experienced numerous instances in which computer illiterates falsely assumed that laptops are constantly connected to the Internet, even (for example) while located on moving vehicles. This, of course, is possible via Wi-Fi or related technologies, but most laptops do not maintain a persistent connection to the Internet. Nevertheless, the perception that laptops are designed to "go anywhere", combined with the growing inseparability of computing and the Internet, have combined to generate confusion as to laptops' networking capabilities. It is unknown how widespread this confusion has spread, though the growth of Metropolitan Area Networks may render this point moot in the future.

External link

@@ Line 39: / Line 39: @@
 The Apple [[PowerBook]] series, introduced in [[1991]], heralded many changes that are now standard on laptops, including [[ergonomic]] improvements such as the placement of the keyboard at the back of the machine, thus creating a palm rest, and the inclusion of a built-in pointing device (a [[trackball]]). The following year, [[IBM]] released its [[Thinkpad]] series, offering similar miniaturization.
-Later PowerBooks introduced the first 256-color displays, first true [[touchpad]], and first built-in [[Ethernet]] [[computer network|networking]].
+Later [[PowerBooks]] introduced the first 256-color displays, first true [[touchpad]], and first built-in [[Ethernet]] [[computer network|networking]].
 == Parts ==