Laptop

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An ultraportable IBM X31 with 12" screen on an IBM T43 Thin & Light laptop with a 14" screen
QWERTY keyboard on 2007 Sony VAIO laptopA laptop computer, or simply laptop (also notebook computer, notebook and notepad) 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 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.

Laptops 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, although typically less powerful for the same price. 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.

Contents [hide]
1 Categories
1.1 Related devices
2 History
3 Parts
4 Disadvantages
4.1 Parts standardization and compatibility issues
4.2 Durability Issues
5 Advantages
6 Upgradeability
7 Performance
8 Health issues
9 Security
10 Major brands and manufacturers
11 See also
12 External links
13 References



[edit] Categories
Thin-and-lights
Laptops usually weighing in between 4 and 6 lb (1.8–2.7 kg) with a screen 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 and infrequently carried out due to their weight and size; the latter provides more space for powerful components and a big screen, usually measuring 17–20 inches (43–51 cm). Desktop replacements tend to have limited battery life, rarely exceeding three hours, because the hardware is not optimized for efficient power usage. Sometimes called a luggable laptop. An example of a desktop replacement computers are gaming notebooks, which are designed to handle 3D graphic-intensive processing for gamers.

[edit] 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:

Transportable, 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 include a magnetized stylus and software for allowing input to be recognized by the touch screen. 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 screen which can be rotated 180 degrees and folded on top of the keyboard. 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 they are able to run some applications, but they can't replace a computer. Internet tablets feature MP3, video, internet browser, chat, and picture viewer.
Personal digital assistants (PDAs)
Small computers, usually pocket-sized, usually with limited functionality. A PDA supports mobile computing, but almost never runs any 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.


An opened Osborne 1 computer, ready for use. The keyboard sits on the inside of the lid.
[edit] 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.

In 1982 Kaypro introduced the Kaypro II, a CP/M-based competitor to the Osborne 1. The Kaypro II featured a display nearly twice as big as the Osborne's and double-sided floppy drives with twice the storage capacity.

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 KB of RAM (expandable to 32 KB).

However, arguably the first true laptop was the GRiD Compass 1101, designed by Bill Moggridge in 1979-1980, 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 kibibyte bubble memory. It was not IBM-compatible, and its high price (US$8,000–10,000) limited it to specialized applications. However, it was used heavily by the U.S. military, and by NASA on the Space Shuttle during the 1980s. The GRiD's manufacturer subsequently earned significant returns on its patent rights as its innovations became commonplace. GRiD Systems Corp. was later bought by the Tandy (now RadioShack) Corporation.

The Ampere[1] a sleek clamshell design by Ryu Oosake also debuted in 1983. It offered a MC68008 microprocessor dedicated to running an APL interpreter residing in Read Only Memory.

Two other noteworthy early laptops were the Sharp PC-5000 and the Gavilan SC, 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 could connect to optional external printers. The Dulmont Magnum, launched internationally in 1984, was an Australian portable similar in layout to the Gavilan, which used the Intel 80186 processor.[2]

The year 1983 also saw the launch of what was probably the biggest-selling early laptop, the Kyocera Kyotronic 85. Owing much to the design of the previous Epson HX-20, and although at first a slow seller in Japan, it was quickly licensed by Tandy Corporation, Olivetti, and NEC, who recognised its potential and marketed it respectively as the TRS-80 Model 100 line (or Tandy 100), Olivetti M-10, and NEC PC-8201.[3] The machines ran on standard AA batteries. The Tandy's built-in 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 with dimensions of 30×21.5×4.5 centimeters (12×8½×1¾ in). Initial specifications included 8 kilobytes of RAM (expandable to 24 KB) and a 3 MHz processor. The machine was in fact about the size of a paper notebook, but the term had yet to come into use and it was generally described as a "portable" computer.

Possibly the first commercial IBM-compatible laptop was the Kaypro 2000, introduced in 1985. With its brushed aluminum clamshell case, it was remarkably similar in design to modern laptops. It featured a 25 line by 80 character LCD display, a detachable keyboard, and a pop-up 90 mm (3.5 inch) floppy drive.

Also among the first commercial IBM-compatible laptops were the IBM PC Convertible, introduced in 1986, and two Toshiba models, the T1000 and T1200, introduced in 1987. Although limited floppy-based DOS machines, with the operating system stored in read-only memory, the Toshiba models 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.

The first laptops successful on a large scale came in large part due to a Request For Proposal (RFP) by the U.S. Air Force in 1987. This contract would eventually lead to the purchase of over 200,000 laptops. Competition to supply this contract was fiercely contested and the major PC companies of the time; IBM, Toshiba, Compaq, NEC, and Zenith Data Systems (ZDS), rushed to develop laptops in an attempt to win this deal. ZDS, which had earlier won a landmark deal with the IRS for its Z-171, was awarded this contract for its SupersPort series. The SupersPort series was originally launched with an Intel 8086 processor, dual floppy disk drives, a backlit, blue and white STN LCD screen, and a NiCD battery pack. Later models featured an Intel 80286 processor and a 20 MB hard disk drive. On the strength of this deal, ZDS became the world's largest laptop supplier in 1987 and 1988. ZDS partnered with Tottori Sanyo in the design and manufacturing of these laptops. This relationship is notable because it was the first deal between a major brand and an Asian original equipment manufacturer.

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

By the end of the 1980s, laptop computers were becoming popular among business people. 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 mebibyte RAM drive, but this reduced its utility as well as its size. The first notebook computers to include hard drives were those of the Compaq LTE series, introduced toward the end of that year. Truly the size of a notebook, they also featured grayscale backlit displays with CGA resolution.


The Macintosh Portable, Apple's first attempt at a battery-powered computerThe 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). Unlike the Compaq LTE Laptop Released earlier in the year the Macintosh Portable was Actually a "luggable" not a laptop, but 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 October 1991, pioneered changes that are now de facto standards on laptops, such as room for a palm rest, and the inclusion of a (a trackball). The following year, IBM released its ThinkPad 700C, featuring a similar design (though with a distinctive red TrackPoint pointing device).

Later PowerBooks introduced the first 256-color displays (PowerBook 165c, 1993), and first true touchpad, first 16-bit sound recording, and first built-in Ethernet network adapter (PowerBook 500, 1994).

In 1994, IBM released RS/6000 N40 PowerPC laptop running AIX (Operating system based on UNIX), manufactured by Tadpole. Tadpole also manufactured laptops based on SPARC and DEC Alpha CPUs.

The summer of 1995 was a significant turning point in the history of notebook computing. In August of that year Microsoft introduced Windows 95. It was the first time that Microsoft had placed much of the power management control in the operating system. Prior to this point each brand used custom BIOS, drivers and in some cases, ASICs, to optimize the battery life of its machines. This move by Microsoft was controversial in the eyes of notebook designers because it greatly reduced their ability to innovate; however, it did serve its role in simplifying and stabilizing certain aspects of notebook design. Windows 95 also ushered in the importance of the CD-ROM drive in mobile computing, and initiated the shift to the Intel Pentium processor as the base platform for notebooks. The Gateway Solo was the first notebook introduced with a Pentium processor and a CD-ROM. Also featuring a removable hard disk drive and floppy drive, the Solo was the first three-spindle (optical, floppy, and hard disk drive) notebook computer, and was extremely successful within the consumer segment of the market. In roughly the same time period the Dell Latitude, Toshiba Satellite, and IBM ThinkPad were reaching great success with Pentium-based two-spindle (hard disk and floppy disk drive) systems directed toward the corporate market.


A 1997 Micron laptopAs technology improved during the 1990s, the usefulness and popularity of laptops increased. Correspondingly prices went down. Several developments specific to laptops were quickly implemented, improving usability and performance. Among them were:

Improved battery technology. The heavy lead-acid batteries were replaced with lighter and more efficient technologies, first nickel cadmium or NiCD, then nickel metal hydride (NiMH) and then lithium ion battery and lithium polymer.
Power-saving processors. While laptops in 1991 were limited to the 80286 processor because of the energy demands of the more powerful 80386, the introduction of the Intel 386SL processor, designed for the specific power needs of laptops, marked the point at which laptop needs were included in CPU design. The 386SL integrated a 386SX core with a memory controller and this was paired with an I/O chip to create the SL chipset. It was more integrated than any previous solution although its cost was higher. It was heavily adopted by the major notebook brands of the time. Intel followed this with the 486SL chipset which used the same architecture. However, Intel had to abandon this design approach as it introduced its Pentium series. Early versions of the mobile Pentium required TAB mounting (also used in LCD manufacturing) and this initially limited the number of companies capable of supplying notebooks. However, Intel did eventually migrate to more standard chip packaging. One limitation of notebooks has always been the difficulty in upgrading the processor which is a common attribute of desktops. Intel did try to solve this problem with the introduction of the MMC for mobile computing. The MMC was a standard module upon which the CPU and external cache memory could sit. It gave the notebook buyer the potential to upgrade his CPU at a later date, eased the manufacturing process somewhat, and was also used in some cases to skirt U.S. import duties as the CPU could be added to the chassis after it arrived in the U.S. Intel stuck with MMC for a few generations but ultimately could not maintain the appropriate speed and data integrity to the memory subsystem through the MMC connector.
Improved liquid crystal displays, in particular active-matrix TFT (Thin-Film Transistor) LCD technology. Early laptop screens were black and white, blue and white, or grayscale, STN (Super Twist Nematic) passive-matrix LCDs prone to heavy shadows, ghosting and blurry movement (some portable computer screens were sharper monochrome plasma displays, but these drew too much current to be powered by batteries). Color STN screens were used for some time although their viewing quality was poor. By about 1991, two new color LCD technologies hit the mainstream market in a big way; Dual STN and TFT. The Dual STN screens solved many of the viewing problems of STN at a very affordable price and the TFT screens offered excellent viewing quality although initially at a steep price. DSTN continued to offer a significant cost advantage over TFT until the mid-90s before the cost delta dropped to the point that DSTN was no longer used in notebooks. Improvements in production technology meant displays became larger, sharper, had higher native resolutions, faster response time and could display color with great accuracy, making them an acceptable substitute for a traditional CRT monitor.
Improved storage technology. Early laptops and portables had only floppy disk drives. As thin, high-capacity hard disk drives with higher reliability and shock resistance and lower power consumption became available, users could store their work on laptop computers and take it with them. The 3.5" HDD was created initially as a response to the needs of notebook designers that needed smaller, lower power consumption products. With continuing pressure to shrink the notebook size even further, the 2.5" HDD was introduced. One Laptop Per Child (OLPC) and other new laptops use Flash RAM (non volatile, non mechanical memory device) instead of the mechanical hard disk.
Improved connectivity. Internal modems and standard serial, parallel, and PS/2 ports on IBM PC-compatible laptops made it easier to work away from home; the addition of network adapters and, from 1997, USB, as well as, from 1999, Wi-Fi, made laptops as easy to use with peripherals as a desktop computer. Many newer laptops are also available with built-in 3G Broadband wireless modems.
Other peripherals may include an integrated video camera and fingerprint sensor.

[edit] Parts

Hard disk from a Dell LatitudeMost modern laptops feature 12 inch (30 cm) or larger active matrix displays with resolutions of 1024×768 pixels and above, and have a PC Card (formerly PCMCIA) or ExpressCard expansion bay for expansion cards. Internal hard disks are physically smaller—2.5 inch (60 mm)—compared to the standard desktop 3.5 inch (90 mm) drive, and usually have lower performance and power consumption. Video and sound chips are usually integrated. This tends to limit the use of laptops for gaming and entertainment, two fields which have constantly escalating hardware demands.[citation needed] However, higher end laptops can come with dedicated graphics processors, such as the Dell Inspiron E1505 and E1705, which can be bought with an ATI Mobility Radeon X1300 or similar. These mobile graphics processors tend to have less performance than their desktop counterparts, but this is because they have been optimized for lower power usage.

There is a wide range of laptop specific processors available from Intel (Pentium M, Celeron, Intel Core and Intel Core 2) and from AMD (Athlon, Turion 64, and Sempron) and also from VIA (C3 and C7-M). Motorola and IBM developed and manufactured the chips for the former PowerPC-based Apple laptops (iBook and PowerBook). Generally, laptop processors are less powerful than their desktop counterparts, due to the need to save energy and reduce heat dissipation. However, the PowerPC G3 and G4 processor generations were able to offer almost the same performance as their desktop versions, limited mostly by other factors, such as the system bus bandwidth; recently, though, with the introduction of the G5s, they have been far outstripped. At one point, the Pismo G3, at up to 500 MHz, was faster than the fastest desktop G3 (then the B&W G3), which ran at 450 MHz.

Some parts for a modern laptop have no corresponding part in a desktop computer. For example, current models use lithium ion and more recently lithium polymer 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 deteriorate over time and eventually need to be replaced in one to five years, depending on the charging and discharging pattern.


A memory module removed from a high-performance Alienware laptopDocking stations became another common laptop accessories in the early 1990s. They typically were quite large and offered 3.5" and 5.25" storage bays, one to three expansion slots (typically AT style), and a host of connectors. The mating between the laptop and docking station was typically through a large, high-speed, proprietary connector. The most common use was in a corporate computing environment where the company had standardized on a common network card and this same card was placed into the docking station. These stations were very large and quite expensive. As the need to additional storage and expansion slots became less critical because of the high integration inside the laptop itself, the emergence of the Port Replicator as a major accessory commenced. The Port Replicator was often a passive device that simply mated to the connectors on the back of the notebook and allowed the user to quickly connect their laptop so VGA, PS/2, RS-232, etc. devices were instantly attached. As higher speed ports like USB and Firewire became commonplace, the Port Replication was accomplished by a small cable connected to one of the USB 2.0 or FireWire ports on the notebooks. Wireless Port Replicators followed.

Virtually all laptops can be powered from an external AC converter. This device typically adds half a kilogram (1 lb) to the overall "transport weight" of the equipment.

A pointing stick or touchpad is used to control the position of the cursor on the screen. The pointing stick is usually a rubber dot that is located between the G, H and B keys on the laptop keyboard. To navigate the cursor, pressure is applied in the direction intended to move. The touchpad is touch-sensitive and the cursor can be navigated by moving the finger on the pad.

Intel, Asus, Compal, Quanta and other laptop manufacturers have created Common Building Block standard for laptop parts.


[edit] Disadvantages

[edit] Parts standardization and compatibility issues
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. 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' internal form factors, 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 users uneducated in the relevant fields, especially if they attempt to connect their laptops with incompatible hardware or power adapters.

Some parts, such as hard drives and memory are commodity items and are interchangeable. However, other parts such as motherboards, keyboards, and batteries are proprietary in design and are only interchangeable within a manufacters brand and/or model line.

A significant point to note is that the vast majority of laptops on the market are manufactured by a small handful of ODMs.[4] 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
Wistron 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

[edit] Durability Issues
Due to their portablility and tight integration, laptops are more subject to wear and physical damage than desktops. Components such as batteries, screen hinges, power jacks, and power cords are commonly subject to deterioration due to ordinary use. A liquid spill onto the keyboard, which is rather minor mishap with a desktop system can damage costly components such as the motherboard or LCD panel. Dropping a laptop can damage the LCD screen if not break apart its body. The repair costs of a failed motherboard or LCD panel may exceed the purchase value of the laptop.

Some manufacturers have mitigated some of these problems by selling "ruggedized" laptops. These often have a special drain in the keyboard that safely routes all of the water out through a hole in the bottom of the case. Additionally, the bodies of these laptops are typically made of magnesium alloy instead of plastic, and hard drives are often braced to greatly increase their chances of surviving a waist-high fall.


[edit] Advantages
Mainly portability:

You can bring your laptop to the computer shop to repair.
One can use the same laptop in classroom and at home.

[edit] 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. [5]

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.

In 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.

In February 2007, a new standard for external PCI Express cables and connectors was announced. Future laptops can be expanded using external PCI Express backplane and chassis.


[edit] Performance

A modern mid-range HP Laptop.For a given price range (and manufacturing base), laptop computational power has traditionally trailed that of desktops. This is partly due to most laptops sharing RAM between the program memory and the graphics adapter. By virtue of their usage goals, laptops prioritize energy efficiency and compactness over absolute performance. Desktop computers and their modular components are built to fit much bigger standard enclosures, along with the expectation of AC line power. As such, energy efficiency and portability for desktops are secondary design goals compared to absolute performance.

For typical home (personal use) applications, where the computer spends the majority of its time sitting idle for the next user input, laptops of the thin-client type or larger are generally fast enough to achieve the required performance. 3D gaming, multimedia (video) encoding and playback, and analysis-packages (database, math, engineering, financial, etc.) are areas where desktops still offer the casual user a compelling advantage.

With the advent of dual-core processors and perpendicular recording, laptops are beginning to close the performance gap with desktops. Intel's Core 2 line of processors is efficient enough to be used in portable computers, and many manufacturers such as Apple, Lenovo and Dell are building Core 2 based laptops. Also, many high end laptop computers feature mobility versions of graphics cards, eliminating the performance losses associated with integrated graphics.


[edit] Health issues

Laptop coaster preventing heating of lap and improving laptop airflow.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 small study, which included little 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 (3.8 °F). Heat from the laptop itself can raise the temperature by another 0.7 °C (1.4 °F), bringing the potential total increase to 2.8 °C (5.2 °F). However, further research is needed to determine whether this directly affects sterility in men. [6] A common practical solution to this problem is to place the laptop on a table or desk.

Heat from using laptop on lap can also cause skin discoloration on the thighs. [7]

Because of their small keyboard, the use of laptops can cause RSI, and for this reason laptops have docks that are used with ergonomic keyboards to prevent injury. Some health standards require that ergonomic keyboards be used in workplaces.


[edit] 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.[8] 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.


[edit] Major brands and manufacturers
Major brands

Acer - TravelMate, Extensa, Ferrari and Aspire
Apple - MacBook, MacBook Air and MacBook Pro
BenQ - S61
Compaq - Evo, Armada, LTE, and Presario
Dell - Inspiron, Latitude, Precision, Vostro and XPS
Gateway
Hewlett-Packard - HP Pavilion, HP Omnibook, HP Compaq Notebooks
Lenovo - ThinkPad, IdeaPad, and 3000 series
Panasonic - Toughbook, Let's Note (available in Japan only)
Sony - VAIO: FJ Series, UX, TZ, NR, SZ, CR, FZ, and AR series
Toshiba - Dynabook, Equium, Portege, Tecra, Satellite, Qosmio, Libretto

ODM brands

ASUS - Asus Eee, Lamborghini
Clevo
Compal Electronics
ECS

Gaming

Abbcore Technologies - Velocita
Alienware - Area 51m, Alienware Sentia and Aurora m
Falcon Northwest - DR6800, TL2
Vigor Gaming - Atlantis, Augustus, Artorius, and Aegis
Voodoo PC - Envy
Dell XPS - M1730 (laptop), and M1530 (laptop)
Other brands

Abbcore Technologies - Desktop, Notebook, Server, Media Center
Acorn Computers - Deskbook, Desknote and Solonote
AVADirect
Averatec
Everex
Fujitsu Siemens - Lifebook, FMV - BiBlo, Amilo
Gericom
HCL
Hypersonic
Hyundai
Jetta (electronics company) - Jetbook
LG - Xnote
LinuxCertified - Linux laptop
MDG Computers
Medion
Micro-Star International (MSI)
NEC - VERSA, LaVie
Neo - Empiriva, Endura
Packard Bell - EasyNote
Samsung - Sens
Seanix - Seanix
Sharp - Mebius
Zenith
Zepto
Wipro Technolgies



[edit] See also
Wikimedia Commons has media related to:
LaptopDesktop computer
Desknote
Desktop replacement computer
List of computer size categories
Open design
Palmtop
Personal computer
PDA
Portable computer
Subnotebook
Tablet PC
Ultra-Mobile PC
NEC UltraLite

[edit] External links
How to Buy a Laptop at HowStuffWorks
How to Add RAM to a Laptop at HowStuffWorks

[edit] References
^ Bob Armstrong, http://cosy.com/language/cosyhard/cosyhard.htm
^ http://www.old-computers.com/museum/doc.asp?c=764
^ See TRS-80 Model 100 / 102 at old-computers.com
^ Notebook OEM/ODM relationships. Retrieved on 2007-06-28.
^ Thus, there is no practical way to update it on models which already feature the latest processor for their motherboard.
^ Sheynkin, Y.; Jung M;Yoo P;Schulsinger D;Komaroff E (2004-12-9). "Increase in scrotal temperature in laptop computer users". Human Reproduction 20 (2): 452-5. Epub. Retrieved on 2006-12-14. 
^ Levinbook, WS.; Mallet J; Grant-Kels JM (2007 Oct). "Laptop computer--associated erythema ab igne.". Cutis 80 (4): 319-20. Quadrant HealthCom. Retrieved on 2008-2-19. 
^ TuxMobil's page with a list of information and protection devices
[hide]v • d • eComputer sizes
Larger Super · Minisuper · Mainframe · Mini · Supermini

Desktop Micro · Home · Personal · All-in-One · Workstation · Server
Mobile Cart / Portable / Desktop replacement computer · Laptop · Subnotebook · Tablet · Ultra-Mobile PC · Electronic organizer · Pocket computer · Handheld game console · Portable / Mobile data terminal · Wearable computer
PDAs / IAs Handheld PC · Pocket PC · Smartphone · PDA phone
Calculators Graphing

Other Embedded system · Wireless sensor network · Smartdust · Nanocomputer

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Categories: History of computing hardware | Laptops
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