Advantages and Disadvantages of Laptop Computer

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
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 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.

Disadvantages

Parts standardization and compatibility issues

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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 problems
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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
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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.Disadvantages

Laptop

A laptop computer or notebook computer 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. These all-in-one systems could be easily transported, but were heavy and usually were not battery powered. The cathode ray tube (CRT) was one of the major reasons portable computers were so large and heavy, but the use of a full-size desktop motherboard with room for ISA expansion cards was another size factor.
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
An Apple 17' MacBook Pro is often used as a desktop replacement.
A 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.
Powerful laptops are 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.
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.[2]

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, Celeron, 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

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2.5" hard disk drive
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.
Processors
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.
Batteries
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.

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 to the overall "transport weight" of the equipment.
"'Docking stations"'
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.
"'Navigation"'
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.
Standards
Intel, Asus, Compal, Quanta and other laptop manufacturers have created Common Building Block standard for laptop parts.

TYPES OF MOBILE COMPANIES

MOBILE COMPANIES IN UNITED KINGDOM

United Kingdom has 73.793 million subscribers in total, or a 121.8% penetration rate.
The country's telecoms regulator is Of com.
Rank Operator Technology Subscribers(in millions) Ownership
1.Vodafone GSM, GPRSUMTS, HSDPA 18.537 [131] (December 2007) Vodafone
2.O2 GSM, GPRS, EDGEUMTS, HSDPA 18.403 [132] (March 2008) Telefónica
3.T-Mobile GSM, GPRSUMTS, HSDPA 17.311 [133] (December 2007) Deutsche Telekom
4.Orange GSM, GPRS, EDGEUMTS, HSDPA 15.642 [134] (December 2007) France Télécom
5.3UMTS, HSDPA (Orange's GSM/GPRS network where the UMTS network is unavailable)
3.90 [135] (March 2007) Hutchison Whampoa
6.UK01 GSM (broadcasts from Spectrum Interactive kiosks) Not Yet Available
Mapesbury Communications Ltd
Mobile Virtual Network Operators
7.Virgin Mobile(uses T-Mobile) GSM, GPRSUMTS, HSDPA 4.52 [136] (December 2006)
Virgin Media
8.Tesco Mobile(uses O2) GSM, GPRS1.5[citation needed] (July 2007) Tesco
9.Blyk(uses Orange) GSM, GPRS, EDGEUMTS 0.1 (April 2008) [137]
Sofinnova Partners and other private investors
10.MobileWorld(uses T-Mobile) GSM, GPRS Not Yet Available The Carphone Warehouse
11.Fresh Mobile(uses T-Mobile) GSM, GPRS Not Yet Available The Carphone Warehouse
12BT Mobile(uses Vodafone)SM, GPRSNot Yet AvailableBritish Telecom
13Dot Mobile(acquired by Vodafone) GSM, GPRS 0.018 jvtv Ltd
14ASDA Mobile(uses Vodafone) GSM, GPRS Not Yet Available ASDA
15Talk Mobile(uses Vodafone) GSM, GPRS Not Yet Available The Carphone Warehouse

HISTORY OF COMPUTER

It is difficult to identify any one device as the earliest computer, partly because the term "computer" has been subject to varying interpretations over time. Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.
The history of the modern computer begins with two separate technologies - that of automated calculation and that of programmability.
Examples of early mechanical calculating devices included the abacus, the slid rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). The end of the Middle Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers. However, none of those devices fit the modern definition of a computer because they could not be programmed.
Hero of Alexandria (c. 10 – 70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions - and when.This is the essence of programmability. In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine". Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.
Large-scale automated data processing of punched cards was performed for the U.S. Census in 1890 by tabulating machines designed by Herman Hollerith and manufactured by the Computing Tabulating Recording Corporation, which later became IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.
During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers.

NOKIA

About Nokia
Nokia is the world leader in mobility, driving the transformation and growth of the converging Internet and communications industries. Nokia makes a wide range of mobile devices and provides people with experiences in music, navigation, video, television, imaging, games and business mobility through these devices. Nokia also provides equipment, solutions and services for communications networks.

MOBIEL

The mobile phone (also called a wireless phone or cellular phone) is a short-range, portable electronic device used for mobile voice or data communication over a network of specialized base stations known as cell sites. In addition to the standard voice function of a telephone, current mobile phones may support many additional services, and accessories, such as SMS for text messaging, email, packet switching for access to the Internet, gaming, Bluetooth, infrared, camera with video recorder and MMS for sending and receiving photos and video. Most current mobile phones connect to a cellular network of base stations (cell sites), which is in turn interconnected to the public switched telephone network (PSTN) (the exception is satellite phones).

COMPUTER

The computer is a programmable machine. The two principal characteristics of a computer are:It responds to a specific set of instructions in a well-defined manner. It can execute a prerecorded list of instructions (a program). Modern computers are electronic and digital. The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called software. All general-purpose computers require the following hardware components:· Memory: Enables a computer to store, at least temporarily, data and programs.· Mass storage device: Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.· input device: Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.· output device: A display screen, printer, or other device that lets you see what the computer has accomplished.· Central processing unit (CPU): The heart of the computer, this is the component that actually executes instructions.In addition to these components, many others make it possible for the basic components to work together efficiently. For example, every computer requires a bus that transmits data from one part of the computer to another.Computers can be generally classified by size and power as follows, though there is considerable overlap:· Personal computer: A small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data.· Workstation: A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.· Minicomputer: A multi-user computer capable of supporting from 10 to hundreds of users simultaneously.· Mainframe: A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.· Supercomputer: An extremely fast computer that can perform hundreds of millions of instructions per second.