Laptop
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http://en.wikipedia.org/wiki/Laptop
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| An ultraportable IBM X31 with 12"
screen on an IBM T43 Thin & Light laptop with a
14" screen |
A laptop computer or laptop
(also notebook computer, notebook and notepad)
is a small mobile computer, typically weighing 3 to 12 pounds
(1.4 to 5.4 kg), although older laptops may weigh more.
Laptops usually run on a single main battery or from an
external AC/DC adapter that charges the battery while it
also supplies power to the computer itself, even in the
event of a power failure. This very powerful main battery
should not be confused with the much smaller battery nearly
all computers use to run the real-time clock and backup
BIOS configuration into the CMOS memory when the computer
is without power.
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.
History
Laptops began from a desire to have a full-featured computer
that could be easily used anywhere. Their predecessor was
called the luggable. These all-in-one systems could be easily
transported, but were heavy and usually were not battery
powered. The CRT was one of the major reasons luggables
were so large and heavy, but the use of a full-size desktop
motherboard with room for ISA expansion cards was another
size factor.
A Compaq luggable PC
It was the transition to LCD and plasma displays that permitted
the luggable to shrink in size and become the first real
laptop, though at first still without internal batteries.
Battery technology improvements and the introduction of
smaller devices such as the 3.5-inch floppy disk permitted
a gradually more compact and sophisticated complete portable
system.
Types
Desktop replacement
A desktop replacement computer is a personal computer that
provides the full capabilities of a desktop computer while
remaining portable. They are often a larger, bulkier laptop.
Because of their increased size, this class of computer
usually includes more powerful components and a larger display
than generally used in smaller portable computers and can
have a relatively limited battery capacity (or none at all).
Some use a limited range of desktop components to provide
better performance per dollar at the expense of battery
life. These are sometimes called desknotes, a portmanteau
of the words "desktop" and "notebook,"
though the term is also applied to desktop replacement computers
in general.
An Apple 17' MacBook Pro is often used as a desktop
replacement.
Powerful laptops meant to be mainly used for fun 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.
Subnotebook
Laptops weighing typically between 0.8 to 2.7 kg and a
screen of 6.4 to 13.3 inches diagonally. A subnotebook is
a small and lightweight portable computer, with most of
the features of a standard laptop computer but smaller.
The term is often applied to systems that run full versions
of desktop operating systems such as Windows or Linux, rather
than specialized software such as Windows CE, Palm OS or
Internet Tablet OS.
Sony VAIO C1 subnotebook.
Subnotebooks are smaller than laptops but larger than handheld
computers and UMPCs. They often have screens around 10.6"
(26.92 cm) (diagonal) and weigh less than 1 to 2 kg, as
opposed to full-size laptops with 14.1" (35.81 cm)
or 15.4" (39.12 cm) screens that typically weigh 2
kg or more. The savings in size and weight are usually achieved
partly by omitting ports or having removable media/optical
drives; subnotebooks are often paired with docking stations
to compensate.
Subnotebooks have been something of a niche computing product
and have rarely sold in large numbers until the 2007 introduction
of the Asus Eee PC and the OLPC XO-1.
Netbooks
A new subgroup of the traditional laptop computer, Netbooks
are smaller, more compact laptops that are designed for
surfing on the internet and basic word processing. Most
of these netbooks use 10 in. screens, weigh at around 1.5
to 3.0 lbs, and are generally powered by either Intel Atom
or Celeron processors, or Via processors, due to their more
favorable Performance Per Watt ratings and cost. They also
use Linux or Windows XP as their default operating systems.
They are also more likely to use Solid State Hard Drives
(SSD) instead of traditional platter Hard Drives.
Parts
Most 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, one or more USB ports,
and a external monitor port (VGA or DVI). Most laptops have
also an ethernet network port. Some have legacy ports such
as a PS/2 keyboard/mouse port or a serial port, parallel
port, and S-video or composite video port. 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,[3] however, higher end laptops can come
with dedicated graphics processors. 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. Some subsystems, such as Wi-Fi, come
in contemporary laptops on replaceable MiniPCI cards, usually
accessible through a door on the bottom. Memory modules
(smaller than the usual DIMMs) are often also accessible
through the bottom, though some may be on the motherboard
under the keyboard and thus not meant to be accessed by
the user.
2.5" hard disk drive
There is a wide range of laptop specific processors available
from Intel (Pentium M, Celeron, Intel Core and Intel Core
2), AMD (Athlon, Turion 64, and Sempron) and 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.
Current models of laptops utilize lithium ion batteries
with more recent models using the new lithium polymer technology.
These technologies have largely replaced the older nickel
metal-hydride batteries. 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 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 his
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.
Laptops typically use SODIMMs, as shown here.
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.
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 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 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).[4] The ODM matters
more than the Original Equipment Manufacturer (OEM). Major
relationships include:
- Quanta sells to (among others) HP/Compaq,
Dell, Toshiba, Sony, Fujitsu, Acer, NEC, Gateway and Lenovo/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 (former manufacturing &
design division of Acer) sells to - HP/Compaq, Dell, IBM,
NEC, Acer, and Lenovo/IBM.
- Flextronics (former Arima Computer
Corporation notebook division) sells to HP/Compaq, NEC,
and Dell.
- ECS sells to IBM, Fujitsu, and Dell.
- Asus sells to Apple (iBook), Sony,
and Samsung.
- Inventec sells to HP/Compaq, Toshiba,
and BenQ.
- Uniwill sells to Lenovo/IBM and Fujitsu.
Durability issues
 |
| Example of how laptop performance slowly
declines after several years, due to dust and lint buildup
on internal heatsinks. Simply blowing air into the vents
is not enough to remove this buildup. Instead, laptop
disassembly is required to properly clean the heatsink. |
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 heatsink 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.
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 and less energy consumption.
Upgradeability
 |
| Laptop computers are very comfortable
& useful on vacation |
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 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
 |
| 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.
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 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. 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.
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.[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.
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:
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 featuring
touchscreen interfaces and a stylus, plus handwriting
recognition software. As of 2007, the most common subcategory
is the Tablet PC, which is essentially a laptop with a
touchscreen. Some tablets have no keyboard, while others
called "convertibles" have a screen that can
be rotated 180 degrees and folded on top of the keyboard.
Tablets may have limited functionality and not be best
suited for applications requiring a 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 cannot replace a general purpose computer. Internet
tablets typically feature an MP3 and video player, web
browser, chat application, 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.
Major brands and manufacturers
- Acer - TravelMate, Extensa, Ferrari and Aspire
- Apple - MacBook, MacBook Air and MacBook Pro
- ASUS - Asus Eee, Lamborghini
- Compaq - Evo, Armada, LTE, and Presario
- Dell - Inspiron, Latitude, Precision,Studio, 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
Gaming
Laptops for children
Other brands
- Abbcore Technologies - Desktop, Notebook, Server, Media Center
- Acorn Computers - Deskbook, Desknote and Solonote
- AVADirect
- Averatec
- BenQ
- Everex - CloudBook, gBook
- Fujitsu Siemens - Lifebook, FMV - BiBlo, Amilo
- Gericom
- Gigabyte Technology
- HCL
- HTC - HTC Shift
- Hypersonic
- Hyundai
- Jetta (electronics company) - Jetbook
- LG - Xnote
- LinuxCertified - Linux laptop
- MDG Computers
- Medion
- Micro-Star International (MSI)
- NEC - VERSA, LaVie
- Neo - Empiriva, Endura
- Noahpad
- OQO
- Orca
- Packard Bell - EasyNote
- PC Club
- Philips - X200
- Pioneer Computers
- Positivo Informática
- Prestigio
- Sager Notebook Computers
- Samsung - Sens
- Seanix - Seanix
- Sharp - Mebius
- Síragon, C.A.
- System76
- VIA - NanoBook, pc-1 Initiative
- Zenith
- Zepto
- Wipro Technolgies
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