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Laptop

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Laptop with touchpad.
An older (1997) Micron laptop.

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). Notebooks smaller than an A4 sheet of paper and weighing around 1 kg are sometimes called sub-notebooks and those weighing around 5 kg a desknote (desktop/notebook). 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 smaller SO-DIMM (Small Outline DIMM) chips 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

The Macintosh Portable, Apple's first attempt at a laptop.

Before laptop computers were technically feasible, similar ideas had been proposed, most notably Alan Kay's Dynabook concept, developed at Xerox PARC in the 1960s and 1970s.

The first portable computers 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 able 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-compatible computer. (IBM's own later Portable Computer was notably less IBM-compatible than the Compaq.)

The first true laptops were the Toshiba T1000 and T1200, introduced 1987. Although limited DOS machines (the operating system was stored in ROM), they were small enough to be carried in a backpack, and could be run off lead-acid batteries.

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.

By the end of the 1980s, laptop computers were becoming popular among businesspeople. The first notebook computers were the Compaq LTE series, introduced in late 1989. Truly the size of a notebook, they had hard drives and standard-resolution screens.

The first transportable Apple Computer machine was the 1989 Macintosh Portable. Another "luggable," rather than laptop, it was praised for its clear active matrix display and long battery life, but was a poor seller due to its bulk.

However, 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 trackpad, and first built-in Ethernet networking.

Parts

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, commonly after two 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.
  • Every laptop is powered or recharged from an AC converter that usually takes the form of a plain black rectangular box. These devices weigh about 1 pound and often take the name "power brick."

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 and above, screen sizes 14 inch (350 mm) or larger, and have PCMCIA expansion bays for expansion cards. Internal hard disks are smaller—2.5 inch (64 mm) compared to the standard desktop 3.5 inch (90 mm) drive—and have lower performance. 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 processorThere are a wide range of notebook processors available from Intel, AMD and IBM. Intel offers the Pentium-M (mobile)processor for notebooks. IBM offers the PowerPC chip which are built into Apple's notebooks. Generally, notebook processor has less powerful speeds than their desktop counterparts.

Upgradability

Laptops generally cost around twice as much as a desktop machine of similar specification. Performance is always 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 changed. 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.

Ultra Light

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 small hard drives, 40 gigabytes or less.

Health concerns

Studies have been conducted to determine if the use of laptops on a man's lap causes harm to his reproductive ability (due to heat). The results are, thus far, inconclusive.

Laptops & Laptop Brands

See also

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