Notebook computers

A laptop is usually shaped like a large notebook with thickness of 0.7-1.5 inches (1.7-4cm) and dimensions ranging from 10x8 inches (27x22cm, 13" display) to 15x11 inches (39x28cm, 17" display) and up. Modern laptops weigh 3 to 12 pounds (1.4 to 5.4 kg), and some older laptops were even heavier. Most laptops are designed in the flip form factor to protect the screen and the keyboard when closed.

Originally considered "a small niche market"¹ and perceived as suitable for "specialized field applications" such as "the military, the Internal Revenue Service, accountants and sales representatives"¹², battery-powered portables had just 2% worldwide market share in 1986³. But today, there are already more laptops than desktops in the enterprise⁴ and, according to a forecast by Intel, more laptops than desktops will be sold in the general PC market as soon as 2009⁵.

History

As the personal computer began to become feasible in the early 1970s, the idea of a portable personal computer followed; in particular, a "personal, portable information manipulator" was envisioned by Alan Kay at Xerox PARC in 1968⁶ and described in his 1972 paper as the "Dynabook"⁷.

The first commercially available portable computer appeared 9 years later, in 1981. The Osborne 1 weighed 23.5 pounds (10.7 kg). It had no battery, a tiny 5" CRT screen and dual 5¼" single-density floppy drives. In the same year the first laptop-sized portable computer, the Epson HX-20, was announced⁸. The Epson had a LCD screen, a rechargeable battery and a calculator-size printer in a 1.6 kg (4 pounds) enclosure.

The first notebook using the clamshell design (which is utilized today by almost all laptops) appeared in 1982: the $8150 GRiD Compass 1100 was purchased by NASA and the military among others. The Gavilan SC, released in 1983, was the first notebook that was marketed using the term "laptop".

Early laptops often had proprietary and incompatible architectures, operating systems and bundled applications.

Classification

The general terms "laptop" or "notebook" can be used to refer to a number of classes of small portable computers:¹⁰¹¹

Desktop replacement

A desktop replacement computer is a laptop that provides most of the capabilities of a desktop computer, with a similar level of performance. Desktop replacements are usually larger and heavier than standard laptops. They contain more powerful components and numerous ports, and have a 17" or larger display. Because of their bulk, they are not as portable as other laptops and their operation time on batteries is typically shorter.¹¹

Some laptops in this class use a limited range of desktop components to provide better performance for the same price at the expense of battery life; in a few of those models, there is no battery at all, and the laptop can only be used when plugged in. These are sometimes called desknotes, a portmanteau of the words "desktop" and "notebook," though the term can also be applied to desktop replacement computers in general.¹²

The names "Media Center Laptops" and "Gaming Laptops" are also used to describe this class of notebooks.¹⁰

Subnotebook

A subnotebook, also called an ultraportable by some vendors, is a laptop designed and marketed with an emphasis on portability (small size, low weight and long battery life) that retains the performance of a standard notebook. Subnotebooks are usually smaller and lighter than standard laptops, weighing between 0.8 and 2 kg (2 to 5 pounds)¹⁰; the battery life can exceed 10 hours¹³ when a large battery or an additional battery pack is installed.

To achieve the size and weight reductions, ultraportables use high resolution 13" and smaller screens (down to 6.4"), have relatively few ports, employ expensive components designed for minimal size and best power efficiency, and utilize advanced materials and construction methods. Some subnotebooks achieve a further portability improvement by omitting an optical/removable media drive; in this case they may be paired with a docking station that contains the drive and optionally more ports or an additional battery.

The term "subnotebook" is usually reserved to laptops that run general-purpose desktop operating systems such as Windows, Linux or Mac OS X, rather than specialized software such as Windows CE, Palm OS or Internet Tablet OS.

Netbook

A netbook is a small laptop designed for portability and low price, with a performance inferior to that of a standard notebook yet adequate for surfing on the Internet and basic word processing. Netbooks use 10" and smaller screens, weigh 0.6 to 1.2 kg (1.5 to 3 pounds), and are generally powered by a CPU from one of the low-cost families with a high performance-to-power ratio such as Intel Atom, Celeron ULV, or VIA C7 processors.¹⁴

Netbooks use general-purpose operating systems such as Linux or Windows XP. Some models use small-capacity (4 to 40 Gb) SSD drives instead of the usual HDDs to save weight and battery power.

Components

The basic components of laptops are similar in function to their desktop counterparts, but are miniaturized, adapted to mobile use, and designed for low power consumption. Because of the additional requirements, laptop components have worse performance than desktop parts of comparable price. Furthermore, the design bounds on power, size, and cooling of laptops limit the maximum performance of laptop parts compared to that of desktop components. ¹⁵

The following list summarizes the differences and distinguishing features of laptop components in comparison to desktop personal computer parts:

Docking stations

A docking station is a relatively bulky laptop accessory that contains multiple ports, expansion slots and bays for fixed or removable drives. A laptop connects and disconnects easily to a docking station, typically through a single large proprietary connector. A port replicator is a simplified docking station that only provides connections from the laptop to input/output ports. Both docking stations and port replicators are intended to be used at a permanent working place (a desk) to offer instant connection to multiple input/output devices and to extend a laptop's capabilities.

Docking stations became a common laptop accessory in the early 1990s. 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 for additional storage and expansion slots became less critical because of the high integration inside the laptop, the "port replicator" has gained popularity. The port replicator was a cheaper, often passive device that simply mated to the connectors on the back of the notebook and allowed the user to quickly connect his laptop so that his monitor, keyboard, printer and other devices were instantly attached. As higher speed ports such as USB and Firewire became common, the connection of a port replicator to a laptop was accomplished by a small cable connected to one of the USB or FireWire ports on the notebook. Wireless Port Replicators are available as well.

A recent variant of the port replicator is the combined power/display/USB hub cable found in the new Apple Cinema Display²³.

Standards

Some laptop components (optical drives, hard drives, memory and internal expansion cards) are relatively standardized, and it is possible to upgrade or replace them in many laptops as long as the new part is of the same type.¹⁸ Subtle incompatibilities and variations in dimensions, however, are not uncommon.²⁴ Depending on the manufacturer and model, a laptop may range from having several standard, easily customizable and upgradeable parts to a proprietary design that can't be reconfigured at all.

In general, components other than the four categories listed above are not intended to be replaceable, and thus rarely follow a standard. In particular, motherboards, locations of ports, design and placement of internal components are usually make- and model-specific. Those parts are neither interchangeable with parts from other manufacturers nor upgradeable. If broken or damaged, they must be substituted with an exact replacement part.

Intel, Asus, Compal, Quanta and other laptop manufacturers have created the Common Building Block standard for laptop parts to address some of the inefficiencies caused by the lack of standards.

Advantages

The main advantage of laptops over their larger desktop counterparts is the inherent portability. Another advantage is the laptop's ability to operate on battery power in the case of a power outage, less energy consumption and heat production.

Disadvantages

Parts standardization and compatibility issues

Current compatibility problems in the laptop trade are reflective of the early era of personal computer hardware, when there were many different manufacturers, each and every one of them having their own connectivity and mounting systems and incompatibility was the 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 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 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 manufactures 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 Original Design Manufacturers (ODM).²⁵ The ODM matters more than the Original Equipment Manufacturer (OEM). Major relationships include:

Durability problems

Due to their portability 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. These components are usually expensive to replace, with a typical laptop battery costing US$130, the AC Adapter US$75.

Other parts are inexpensive, such as a power jack costing perhaps US$20, but replacement may require extensive disassembly and reassembly of layers of internal components. Other inexpensive but fragile parts often cannot be purchased separate from larger more expensive components. For example, the video display cable and backlight power cable that passes through the lid hinges to operate the screen will eventually break from opening and closing the lid hundreds of times over many years, and usually these tiny cables cannot be purchased separate from an entire US$400 LCD panel.

A liquid spill onto the keyboard, which is rather a 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.

Laptops must also rely on extremely compact cooling systems involving a fan and heat sink that eventually fails due to filling with airborne dust and debris. Most laptops do not have any sort of removable dust collection filter over the air intake for these cooling systems, resulting in a system that gradually runs hotter and louder as the years pass. Eventually the laptop cooling is so choked with dust that it starts to overheat just from minor operational load. This dust is usually deeply buried inside where casual cleaning and vacuuming cannot remove it, and instead complete disassembly is needed to clean the laptop.

Rugged laptops

Some manufacturers have mitigated some of these problems by selling "ruggedized" laptops. These often have a rubber sheeting under the keyboard keys and special drain 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 a stiffer magnesium alloy instead of plastic, since it is the flexing of the circuit boards and fragile mechanical devices that causes the most damage. Hard drives are often mounted in soft shock-absorbing silicone mounts to greatly increase their chances of surviving a waist-high fall.

When a laptop hits the floor, the free-floating hard drive heads can slap against the spinning platter, scratching it and cause an irrepairable head crash that renders the hard drive unusable. Recently hard drives have been constructed which can move the read heads completely off the spinning platters, known as unloading. With the use of an accelerometer, the hardware can detect the sudden fall and park the heads off-platter before the laptop hits the ground. (See Sudden Motion Sensor.)

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.²⁶

Many laptops also include an internal MiniPCI slot, often occupied by a Wi-Fi 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

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 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.

As computer hardware miniaturization develops, 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 Inc., 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, while maintaining long battery life.

Health problems

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.²⁷ 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.²⁸

Because of their small keyboard and trackpad pointing devices, the use of laptops can cause RSI, and for this reason laptops have docks that are used with ergonomic keyboards to prevent injury. The integrated screen often causes users to hunch over for a better view, which can cause neck or spinal injuries. Some health standards require that ergonomic keyboards be used in workplaces.

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.²⁹ 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.

Related devices

A laptop can use the same software as a desktop machine but is small enough to support mobile computing and operate on battery power. Devices that are similar to a laptop include:

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.

Major brands and manufacturers

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