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A laptop computer, or simply laptop (also notebook computer or notebook), is a small mobile computer, which usually weighs 2.2-12 pounds (1-6 kilograms), depending on size, materials, and other factors.

While the terms laptop and notebook are often used interchangeably, "laptop" is the older term, introduced in 1983 with the Gavilan SC. "Notebook computer" is a later coinage, which was used to differentiate smaller devices such as those of the NEC UltraLite and Compaq LTE series in 1989, which were, in contrast to previous laptops, the approximate size of an A4 paper sheet. The terms are imprecise: due to heat and other issues, many laptops are inappropriate for use on one's lap, and most notebooks are not the size of typical A4 paper notebook. Although some older portable computers, such as the Macintosh Portable and certain Zenith TurbosPort models, were sometimes described as "laptops", their size and weight were too great for this category.

Laptops usually run on a single battery or from an external AC/DC adapter which can charge the battery while also supplying power to the computer itself.

As personal computers, laptops are capable of the same tasks as a desktop PC, 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.

Many schools have taken in laptop based programs in which every student receives a laptop for school use only. The operating system is configured (or a third party program is installed) to limit the student's access to perform administrative tasks such as hardware or software installation, or operating system modifications. Students are generally permitted to use these systems to take notes, write papers, and perform other school-related activities.

Categories

Terms sometimes used for subtypes of laptop computers include:

Ultraportables

Laptops with screens typically less than 12 inches diagonally and a weight of less than 1.7kg. 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 and/or battery life, house power-saving CPUs and almost always have integrated graphics.

Thin-and-lights

Laptops usually weighing in between 1.8kg and 2.8kg with a screen size of between 12 and 14 inches diagonally. Examples of this variety: the Sony VAIO FJ, Apple MacBook and Dell XPS M1210.

Medium-sized laptops

These usually have screens of 14 - 15.4 inches diagonally and a weight of around 3-3.5kg. They usually sacrifice a little computing power for smaller dimensions and longer battery life, although the length and width are usually determined by the screen size.

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. Desktop replacements tend to have limited battery life, rarely exceeding three hours, because the hardware is not optimized for efficient power usage.

Parts

• Most modern laptops feature 12 inch (304.8 mm) 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 (63.5 mm)– compared to the standard desktop 3.5 inch (88.9 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. 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:

• 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.
• Docking stations became 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 were 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.

Spare categories

While there are accepted world standard of form factors for all the peripherals and add-in PC cards used in the desktop computers, there are still no world standard form factors for all the laptop computers used today, such as supply of electric voltage, layout of mother board, adapters used in connecting the hard disk, optical drive, LCD cable, keyboard and floppy drive to the main board. Every manufacturer created and used their own design in manufacturing the proprietary parts for their own brand of laptop. Some parts made by laptop producers aren't interchangeable with other manufacturers. Consumers ultimately pay for the additional cost that could have been saved if having the standard form factor for the laptop parts.

The name of the parts or the name of category used also differs from manufacturer to manufacturer, such as "system board" used by IBM and "motherboard" used by Compaq, "display cable", "LCD cable", "flexi-cable" are the terms used by the general public refer to the cable connecting the LCD screen to the main board for transferring the digital signal. The cover around the keyboard where the palm is rested is called the "palm rest" by Dell, the "keyboard bezel" by IBM, the "upper cpu cover" by Compaq and the "top case sub assembly" by Asus.

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Summary all the differences there are 7 main categories consisting of 100 sub categories for all the spare part used in all laptop computers as organized by pchub, there are also 8 categories for parts, such as hard disk and optical drive manufactured by the OEM (Original Equipment Manufacturer), which are the common parts that generally used in all the laptop.

Main categories for all the laptop spare parts.

Laptop Spare Part: »Adaptor / Battery »Fan / Hinge / CPU »LCD Related »Main/Key/ Board Related »Drive Related »Cover / Casing Related »Docking / Replicater

OEM Spare Part: »AC Adapter »DC Car Adapter »LCD »Fluorescent Tube »Optical Drive »Various jack »Floppy »Hard Disk 2.5"

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.

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.

Performance

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 larger 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 PCs. Intel's Core 2 line of processors is efficient enough to be used in portable computers, and many manufacturers such as Apple Computer 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.

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. Heating of the scrotum is known to cause temporary sterility in men. article health and laptops

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. Most laptops have a security slot to chain the computer to a desk with a third party security cable.

Manufacturers

See also

• Desktop computer
• Desknote
• Desktop replacement computer
• List of computer size categories
• Open design
• Palmtop
• Personal computer
• PDA
• Portable computer
• Subnotebook
• Tablet PC
• Ultra-Mobile PC

Notes

1. As far as this distinction is concerned, the "thickness" ("vertical height") of the machine is disregarded; only its width and depth are considered
2. Thus, there is no practical way to update it on models which already feature the latest processor for their motherboard.
3. Sheynkin, Y. (2004-12-9). "Increase in scrotal temperature in laptop computer users". Human Reproduction. 20 (2). Epub: 452–5. Retrieved 2006-12-14. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
4. TuxMobil's page with a list of information and protection devices

• History of computing
• Laptops
• Mobile computer
• Portable computers