CHAPTER 1 FUNDAMENTALS OF A PERSONAL COMPUTER (PC)

Chapter Objectives:
	Identify the functions of the PC
	Explain the different types of computers
	List the components of the PC
	Discuss the Power-On Self Test (POST)
Introduction :
	Computer is an integral part of everyday life. We use the Personal Computer (PC) to perform various tasks. Data storage and processing are the important tasks performed by the PC. It can store, process, and print documents. The use of the PC makes mathematical calculations easier. Scientists use the PC for scientific applications, such as weather forecasts, research, and chemical analysis. PC provides the speediest means of communication through the Internet by sending and receiving e-mails. We can use the Internet to gain information on any topic. We can use the PC for entertainment, such as for watching movies using DVDs, listening to music using CDs and MP3s. We can also download software, graphics, music, and movies from the Internet using the PC. It would be hard to imagine today's world without the PC. A machine that performs such a varied range of functions is hard to define in a few words. Computer is an electronic device that accepts, stores, and processes the data and returns the result or output.
1.1 Functions of a PC
	Personal computer has a microprocessor for processing the data, a keyboard for entering the data, a monitor for displaying the data, and a storage device for storing the data. PC performs many functions such as:
	Accepting Data – Accepts data input from the user. PC accepts input through various input devices like the keyboard, mouse, or microphone.
	Storing Data – Enables to store large amount of data. This helps to recover the data stored earlier. It can store the data permanently on the storage devices such as the hard disk drive, floppy disk drive, or tape drives.
	Processing Data – Performs operations on the input data. A set of instructions starts these operations. These instructions are either stored in the memory or built into the microprocessor. Data processing is the process of manipulating the data using a set of instructions and producing the desired output. For example, when we write a program and give some input, PC processes the input according to the program and returns the output. In this case, the program is the set of instructions that the PC uses to process the data, which is the input.
	Displaying Data – Shows the processed data to the user. This data can be in the form of binary numbers, characters, or pictures. PC displays the output through various output devices, such as monitors, printers, or speakers. Any device that gives the output from a computer is called the Output device. For example, when we play a CD or DVD, what we see on the monitor or hear from the speakers is the output. The documents that we print after typing and processing are the forms of output from the PC.
	The entire process of accepting the data, processing it, and displaying the processed data is called the Input-Process-Output cycle.
1.2 Types of Computers
	Computers perform a vast range of functions. Some computers are so powerful that hundreds or even thousands of users can use them at a single instant. Computers have different types of capabilities and sizes. Classification of computers is based on the usage, speed, and size of computers. There are four main types of computers, namely Microcomputers, Minicomputers, Mainframes, and Supercomputers.
	1.2.1 Microcomputer
	Microcomputer, also known as a personal computer, is a digital computer that works on a microprocessor. Microcomputers are small machines designed for individual users. Average people who have a basic knowledge of computers can use microcomputers. Individuals at home and office are the major users of the microcomputer. It is an inexpensive computer that performs tasks such as word processing, desktop publishing, and accounting. It is also useful for running spreadsheets and database management applications.Microcomputers are widely used for entertainment purposes such as for playing games, listening music, and watching movies. The microcomputer is also widely used to access the Internet. The microcomputer has several advantages such as small size, low cost, and portability. Its main disadvantage is that the speed of processing is low as compared to other types of computers.
	1.2.2 Minicomputer
	Minicomputer is a medium sized multiprocessing and multi-user computer. Multiprocessing is the process of running multiple programs or processes at a given instant. The minicomputer is a medium range computer. It is also known as the mid-range server. Minicomputers fall in the category between the microcomputers and the mainframes. The advantage of using a minicomputer is that it can cater to multiple users at a lower cost than mainframes. Minicomputers are ideal for small-sized companies. The disadvantage of the minicomputers is that they are large and bulky.
	1.2.3 Mainframe
	In the beginning, mainframes were huge computers occupying entire rooms or floors. Mainframes were used to serve as the center of large systems in companies. They were designed to serve the purpose of centralized computing instead of the distributed computing. With the development in the field of computing, the size of mainframes has reduced and the power has increased. They now serve distributed users and small servers in a computing network. They are also known as enterprise servers. Mainframes are very large and expensive computers. Thousands of people can use a mainframe at a time. It can process millions of transactions everyday. The advantage of mainframes is that it can support so many users and instructions because of its incomparable memory. The disadvantage of mainframe is its huge size and enormous cost. As a result, mainframes are widely used in large companies worldwide. Mainframes specialize in processing bulks of data. This is the reason why the mainframe is widely used for government purposes.
	1.2.4 Supercomputer
	Supercomputer is the fastest and most expensive type of computer. Supercomputers specialize in high-speed processing of data. Applications that require large amounts of calculations use supercomputers. Some of these applications are molecular chemistry, nuclear research, weather reports, and advanced physics. Supercomputer can be a single or multiple computer system. In multiple computer system, a supercomputer consists of several computers that work in parallel as a single system. The advantage of supercomputers is their speed, which is unmatched by any other type of computer. A major disadvantage of supercomputers is that they generate a large amount of heat during their operation. Hence, it is important to use effective cooling solutions. Also, a supercomputer tends to specialize in numerical applications and does not perform as well on other applications.
1.3 Components of a PC
	A PC comprises of hardware and software. Everything that you can see and touch in the PC is called the hardware. The computer consists of large number of components. Each of these components are essential for the functioning of the PC. The input devices, output devices and the storage and processing devices are the different components of the PC.
	1.3.1 System Case
	System case is a box that is made up of plastic and metal. It provides a cover for all the main components of the computer. It plays an important role in the functioning of a computer. The System case performs various roles in the following areas:
	Protection – Prevents dust and foreign particles from entering into the internal components of the computer. PC produces a lot of radio-frequency (RF) interference as it works. The system case protects electronic devices located near the computer from the RF interference generated in the PC. The system case also protects the internal wires and cables. It shields the user from electric shocks. An inferior quality system case would cause a great deal of damage to the PC as well as to the electronic devices near it.
	Well-defined Structure – Organizes all the components of the PC in a structured manner. The system case contains the motherboard, which is the most crucial part of the PC. All other internal components are mounted either on the motherboard or on the system case itself. Therefore, the system case plays an important role in structuring the parts of a PC. A system case must have enough space to contain all these parts. Proper placement of the internal components is important for their efficient functioning. An overcrowded system case would effectively reduce the lifetime of the PC components.
	Expandability – Allows adding additional devices such as a hard disk, CD-ROM, and floppy disk drive to the system case. A system case that is small would not offer many options for expansion.
	Cooling – Protects internal components of a PC from adverse effects of heat. The different components of the PC produce heat due to their working. This heat is highly damaging to the internal parts of a PC. The system case must be large enough to provide air circulation in the interior. The power supply fan in the system case keeps the power supply cool. A system that has poor cooling will fail suddenly, without showing any signs of trouble.
	Status Display – Indicates the functional status of the PC through lights. The lights on the system case are called LEDs. Some of the LEDs such as Power LED are built into the case while others are the parts of the devices mounted on the case. The Power LED indicates whether the PC is switched on or off. The CD-ROM LED indicates whether the CD-ROM drive is in use or not.
	1.3.2 Power Supply
	The Power supply of the PC converts the standard household power supply to a form that is usable by the PC. The power supply supplies power to every component of the PC. The power supply is visible from the back of the PC. It is recognizable by the power supply fan and the power cord connector. The power supply is situated in a corner of the system case. A case and a metal cover on the top of the case cover the power supply. The power supply case protects the internal parts of the power supply. It also isolates the parts of the power supply from the rest of the PC. It protects the PC user from electric shocks. The power supply has various connectors that connect to the motherboard and disk drives.
	The various uses of the power supply are :
	System Cooling – Controls the power supply fan, which performs the function of cooling of the system components.
	Performance Stability– Is crucial to the proper functioning of the PC. An inefficient power supply can lead to problems like system bugs and hard drive problems, which do not even appear related to the power supply.
	Reduction of Power Consumption – Plays an important role in the conservation of electricity.
	Expandability Options – Is an important factor in the upgrade of a PC. The power supply should be efficient enough to support additions to the system. If the power supply does not have the required capacity, it will have to be replaced.
	1.3.3 Motherboard
	Motherboard is the main circuit board of a PC. It contains the interfaces for the microprocessor, BIOS (Basic Input Output System), memory, and storage devices. The serial and parallel ports, and all the controllers needed to control the peripheral devices such as the monitor, keyboard, and mouse are affixed on the motherboard. It also contains expansion slots for fixing additional boards to the motherboard. The collection of chips and sockets that reside on the motherboard are known as its chipset.
	1.3.4 I/O Ports and Cables
	The I/O Ports and cables connect the input and output devices to the PC. Input and output are the basic functions of a PC. The I/O ports and cables provide the means to establish connections to external devices. The different types of I/O ports are:
	Serial – Connects to devices such as modems, printers, and digital cameras. Serial ports are the oldest kinds of ports in use. They transmit data in a serial fashion. Serial ports enable data flow in both directions.
	Parallel – Connects to scanners, CD burners, hard drives and printers. Parallel ports are much faster than serial ports. These ports transmit data in a parallel manner. Parallel ports are wide in size to enable parallel transmission of data.
	USB –Connects to a wide range of devices like mouse, keyboard, modems and speakers. USB stands for Universal Serial Bus. USB is fast becoming a popular replacement for serial and parallel ports. This is because USB is highly advanced, fast, and simple to use.
	The I/O cables connect the PC to different I/O devices. The I/O cables are very important to the connections formed by a PC. There are different types of cables available, such as Shielded Twisted Pair (STP), Unshielded Twisted Pair (UTP), and fiber optic cables.
	1.3.5 Storage Devices
	Storage Devices store data in the computers. There are several types of storage devices for computers. These storage devices offer a wide range of storage options. Floppy devices store 1.44MB of data. Advanced storage devices store several gigabytes of data. The different types of storage devices are:
	Magnetic devices – Are the most common form of data storage. Magnetic devices like floppy devices, zip drives, and portable drives are highly popular forms of data storage devices.
	Optical devices– Provide large amount of data storage. The Compact Disk (CD) is the most common form of optical storage device. Optical devices are very compact and inexpensive. The PC reads data from optical devices with the help of a laser beam.
	Solid-State Storage devices– Use flash memory for storing data. Digital cameras and memory cards for video games are types of solid-state storage devices. These devices are very light and small in size. The speed of operation is high in solid-state storage devices.
	Digital Audio Tape – Digital Audio Tapes (DAT) provides a digital means of recording music. Digital music contains a huge volume of data. DAT uses a rotary head that rotates diagonally across the head of the tape. The rotary head records the music. As a result, we also call DAT by the name R-DAT, where R stands for Rotary.DAT provides superior quality and high speed of music recording. The DAT provides about 180 minutes of music on a single tape. DAT does not use data compression while recording.
	1.3.6 Display System
	The monitor is used as the display system of the PC. The monitor screen is the projection surface, where images are projected. PC monitors are available in sizes of 14, 15, 17, 19, and 21 inches. The monitor uses a device called adapter that converts digital data from the computer to analog data. The types of adapters commonly in use today include the Ultra Extended Graphics Array (UXGA) adapter and the Video Graphics Array (VGA) adapter.
	1.3.7 Display Card
	The display card or video card is responsible for the visual effects on a PC. The display card takes the data from different parts of the computer and takes it to the monitor in a format that the monitor can use. Modern display cards are very advanced and can store images as well. This reduces the burden on the CPU. The display card is a very important part of the PC for applications like games and graphics. The display card is responsible for the quality of the images. This is crucial to the comfort of the PC user. There are many types of display cards that are usable in PCs.
	1.3.8 Modem
	Modem is a device that modulates and demodulates information between two devices across a network. Modem is an abbreviation for modulator/demodulator. It is a device that sends digital information across a telephone network.
	The information sent by a computer to the network is in digital form. The telephone network cannotuse digital data. The modem modulates the data into information that is compatible with the network. This information passes across the network. The data that comes out of the network is not in digital format. The computer on the other end cannot use this data. As a result, the modem on the other side of the network demodulates the data to digital format that is compatible with the receiving computer. We use many online services effectively with the help of the modem. A modem can be an internal component of the PC or it can be an external device. We connect external modems to the serial port of the computer.
	1.3.9 Sound Card
	The Sound card is a component that is responsible for the sound effects of a computer. It has several components that contribute to the production of sound on the speakers. The different functions of a sound card are:
	Processing and synthesizing of sound Playing music from CDs, MP3s and DVDs Recording audio from devices such as microphones
	The sound card stores audio information in memory. It converts digital data from the PC to analog data that the sound devices use. It also converts analog data from audio devices to digital data that can be stored in memory. It uses a MIDI (Musical Instrument Digital Interface) for connecting to audio devices. We can connect speakers and a microphone of to the sound card.
	1.3.10 LAN Card
	The LAN card connects the PC to a network. The LAN card enables connections to other computers. We exchange data and resources across a network. The LAN card is crucial to this objective. Companies can share devices like printers across a network and access data in an intranet.
	1.3.11 Network Cables
	Network Cables connect the PC to the Internet or any other network. There are different types of network cables. The network cables commonly used are Shielded Twisted Pair (STP), Unshielded Twisted Pair (UTP), Coaxial cable, and Fiber Optic cable.
	Unshielded Twisted Pair (UTP) Cable - UTP is a very popular type of network cable. It is widely used in small networks. The UTP consists of four pair of wire inside a covering jacket. The pairs of wire are twisted. The twisting protects the wires from interference effects. The amount of twisting is different from one cable to another. Better quality cables have a higher amount of twisting.
	Shielded Twisted Pair (STP) Cable - STP cable is a shielded version of the UTP cable. UTP cable is prone to interference effects. The interference can be radio interference or electrical interference. The shielding in STP cable protects it from most of the interference effects. STP is heavier and larger than UTP because of the covering.
	Coaxial Cable - Coaxial cable provides high degree of protection from external interference. The coaxial cable consists of a copper rod in the center. The copper rod is a conductor. A plastic layer covers it. A metal shield covers the plastic layer. The plastic layer provides insulation between the copper rod and the metal shield. The metal shield provides protection against interference from other devices. The complicated design of the coaxial cable makes it difficult to install. The high level of interference resistance makes it popular in use. There are two types of coaxial cable called thinnet and thicknet. Thinnet is thin coaxial cable and thicknet is thick coaxial cable.
	Fiber Optic Cable - Fiber Optic Cable provides total immunity to electrical interference. This is because it consists of a glass core. A protective layer of plastic covers it. The plastic offers a cushioning effect for the glass. Metal wires cover the plastic. Fiber optic cable emits light and not electrical signals. As a result, electric interference is impossible. An external insulating layer covers the cable. The resistance from electric interference makes it immune to electricity hazards like lightning. These features make the optic fiber cable highly popular in external environments and places that have high electric interference. Fiber optic cable has high speeds of data transmission. It can transmit information over long distances.
1.4 Introducing the Front and Back Side of the PC
	We can identify the front and back sides of the PC by looking at the CPU. We can see different parts of the PC on the front and back sides. The front of the PC contains the power switch. We use the power switch to turn on the PC. We insert CDs and DVDs in the CD/DVD drive. We use floppy disks with the help of the floppy drive. The LED display on the front of the PC indicates the status of the system. On the back side of the PC, we can see the power supply and the cooling fan. The input and output ports of the PC are situated on the back of the PC. We connect devices like the mouse and keyboard to the ports at the back of the PC. In addition, the back of the PC has several ports for connecting the sound devices, the monitor and the modem.
1.5 Starting a PC for the First Time
	When we start the PC, the Basic Input Output System (BIOS) runs a test to check if all the peripheral devices, memory and hardware of the PC are working properly. This test is called the Power On Self Test (POST). The PC will boot only if the results of the test are positive. If any of the above components of the PC are not in proper condition, the PC will give some warning signals like beeps. In some cases, if the problem is serious, the PC will not boot at all. The POST happens as soon as the PC starts and before most of the components of the PC start. The errors that cause the system to stop booting are of two types – fatal and non-fatal. In case offatal errors, the boot process stops immediately. The following are the functions performed by POST:
	_ Checking the motherboard
	_ Comparing the system configuration with the PC Configuration Program to find any changes made
	_ Checking the memory devices and drives
	_ Checking the system memory
	_ Starts the display and audio devices
	In case there are no errors in the system configuration or devices, a single beep follows the POST. Then the booting process of the PC starts and the operating system is loaded.
	Power Supply Fan Power Supply of PC Mouse Port USB Port Parallel Port Monitor Port SCSI Port Keyboard Port Firewire Port Serial Ports Network Port Sound PortModem Port
Summary :
	In this Chapter you learnt :
	_ The Personal Computer is an electronic machine that accepts data, processes it on the basis of some instructions and produces an output.
	_ The basic functions of a PC are data input, storage, data processing and output.
	The different types of computers are: _ Microprocessors _ Minicomputers _ Mainframes _ Supercomputers _ The system case provides a protective cover for all the important components of the PC. _ The system case performs the important function of keeping the system components cool. _ The outer appearance of a PC and its expansion options depend on the structure of the system case. _ We insert devices like CDs, floppy disks and DVDs in the slots on the system case. _ The LED displays on the system case indicate the operations going on inside the PC. _ The different ports for connecting different devices are located on the back of the system case. _ The power supply of the PC converts the alternating current to direct current that the PC uses. _ The motherboard is the main part of a PC, which contains the Central Processing Unit (CPU) and the Basic Input Output System (BIOS). _ The I/O ports connect the different devices like printers and CDs to the PC _ The different types of I/O ports are:_ Serial_ Parallel_ USB_ I/O cables form the connection between I/O devices and the I/O ports. _ Storage devices store data from PCs.
	The different types of storage devices are: _ Magnetic_ Optical_ Solid-state Storage_ Digital Audio Tapes (DAT) record and store music digitally. _ DAT provides speedy access to music with high quality. _ The display system of the PC is the monitor. _ Modems are devices that modulate and demodulate information. _ PCs used modems to access networks through telephone lines._ The sound card produces and processes sound output._ The LAN card connects a PC to a network. _ The display card produces the visual effects on the monitor of the PC. _ Network cables connect PCs to the Internet or an Intranet. The different types of network cables are: _ Unshielded Twisted Pair (UTP) _ Shielded Twisted Pair (STP) _ Coaxial_ Fiber Optic _ The BIOS runs a test called Power on Self Test (POST) when a PC turns on. _ The POST checks the PC memory, configuration and peripheral devices. _ The PC does not boot if the POST fails.

CHAPTER 19 WORKING WITH A PORTABLE PC
	Chapter Objectives :
	At the end of the Chapter, you will be able to : _ List the types of portable PCs _ Explain the features of a laptop _ Explain laptop design _ List the different components of a laptop _ Identify the laptop input and output devices _ Troubleshoot a laptop
	Recall :
	In the previous Chapter you learnt that the printer is a peripheral output device that prints data processed in the computer. Printers can be classified as impact printers and non- impact printers on the basis of operation. You can identify printer quality on the basis of features such as speed and dots per inch. 1. Explain the different types of printers? 2. List various types of impact printers. 3. List the various types of non-impact printers.
	You Have to Study Again
	4. Explain the working of laser printers. 5. List the steps to install a printer.
	Introduction :
	You can use portable PCs while traveling, at home or any other place of choice. Portable PCs are highly used in fields such as education, science and business, among others.
19.1 Types of Portable PCs
	Portable PCs vary in size and features. One type of portable PC is the laptop that is comparable to a briefcase in size and structure. Notebooks and subnotebooks are smaller versions of laptops. The palmtop is small enough to be held in the palm of the hand.
	19.1.1 Laptops
	A laptop is a portable computer that can perform all of the tasks carried out by a desktop system. This type of computer is small enough to fit on the lap of a person, hence the name. You can use a laptop to create programs, multimedia applications, word documents, presentations, and spreadsheets. A laptop is like a briefcase in structure and you can carry it around wherever you go. A laptop appears.
	19.1.2 Notebooks
	A notebook is an extremely small and lightweight version of a portable computer. They can fit into a briefcase and be carried around. Currently, notebooks and laptops are virtually the same in most respects. Notebooks use flat panel technologies to produce a lightweight display screen. A notebook appears.
	19.1.3 Subnotebooks
	Subnotebooks are a smaller and lighter version of the notebook. They generally have smaller keyboards and screens as compared to notebooks. Subnotebooks usually have external drives and may have the serial and parallel ports on an external device. A subnotebook appears.
	19.1.4 Palmtops
	As the name suggests, palmtops are computers that you can carry around in the palm of your hand. These computers use a pen for input and not the keyboard. Most palmtops do not have disk drives because of their size limitations. Palmtops are also called Personal Digital Assistants (PDAs), handheld computers or pocket computers. A palmtop and the pen appear.
19.2 Features of Laptop
	The features of laptops vary based on the model of the laptop. Its features determine the usage and convenience of a laptop. The different characteristics of a laptop that determine its usage are: _ Weight - Is an important feature of the laptop, since its key function is to allow easy carriage and use. The weight of laptops range from 2 to 5 Kgs. A laptop must be light enough to carry around with ease. _ Size - Must fit into the user's bag or case with ease. A smaller laptop can be handled with ease. As a result, smaller laptops are considered more viable. _ Case material - Is a key feature of laptops. The case cover must be strong enough to withstand pressure in the case of a fall. You must find out the composite material of a laptop case cover. _ Cost - Differs widely based on the features of a particular model. Laptops are considerably costlier than desktop systems, due to their portability. _ Interface - Must be comfortable to the user. The screen display must be clear. The keyboard and other input devices must also be easy to use. The keyboard of a laptop is slightly different from that of desktop systems. Also, laptops are provided with input devices like a trackpoint or touchpad in order to move the cursor on the screen. These mechanisms can be used in place of the mouse.
19.3 Laptop Design
	The design of a laptop depends on the applications it will be used for. The design of a laptop is implemented based on various points. The most important point to be considered while designing a laptop is its portability. The design characteristics of a laptop are: _ Size and weight - Kept to a minimum to ensure ease of transportation. _ Screen size - Restricted between ranges of 12 inches to 17 inches. The screen is designed using Thin Film Transistor (TFT) display. TFT is a type of Liquid Crystal Display Technology that ensures superior screen display. _ Performance -Is a key point to be considered in the design of the laptop. The level of usage and performance expected from a particular model is very important to consider while designing it. _ Battery life - Must help in elevation of the life span of a battery. The laptop CPU is a key component that decides the lifetime of a battery. _ Onboard Components - Must be placed so as to limit the size of the laptop. However, the number of components in modern laptops is no longer limited. The components must be arranged in a manner that enables good connectivity between users. _ Ports and sockets - Enable connection to various devices. The different ports like firewall, USB and parallel port connect to different devices. The power socket, modem socket and network socket are some other important ports that must be considered while designing a laptop. The ports on the laptop must be designed to allow easy connection to devices like a phone or camera. These must also enable the user to have network access.
19.4 Laptop Components
	Laptops have different components like the motherboard, memory, ports and sockets that work together to provide the functionality of the laptop. You can connect different devices to the laptop with the help of the ports. The infrared ports on a laptop enable wireless connections.
	19.4.1 Motherboard
	The motherboard is the most important component of the laptop. It connects directly or indirectly to all the components of the laptop. Laptop motherboards have very advanced features.
	19.4.2 Memory
	Laptops have RAM and ROM, similar to ordinary desktop computers. However, the memory modules of laptops are different as compared to desktop computers. The laptops mostly use Small Outline Dual Inline Memory Module (SODIMM). These modules are small in size and have capacities between 16 MB to 1GB. Laptops generally have a minimum of 64 MB of RAM.
	19.4.3 Microprocessor
	The microprocessor is the central unit that co-ordinates all the functions of the laptop. It performs all the operations of the laptop, according to instructions from the operating system. Laptop microprocessors have additional features that enable reduction of power consumption. Laptop microprocessors also have multiple sleep modes. They operate at lower voltages. This increases the battery life. The features of a laptop microprocessor are : _ The microprocessor stores its instructions in the memory. It refers to the memory periodically when it is performing a task. _ It receives data input from the user though a mouse, keyboard, trackball, or touchpad. _ It sends data output to the user through the monitor. It also sends data output to other devices such as the printer or modem. It also enables data transfer though networks. _ The microprocessor receives data through different storage devices like CD/DVD drives, floppy drives, or hard drives. It can also store data in disks by using these devices.
	19.4.4 Hard Drives
	The Hard Drive is present internally in all laptops. This drive stores the operating system, applications and data. A laptop hard drive generally has a capacity between 6 and 80 GB. A laptop hard drive works in the same manner as a desktop hard drive. However, due to space limitations, the disk space is limited on laptop hard drives.
	19.4.5 Floppy Drives
	The Floppy Drive in the laptop enables storage of data to a floppy disk. You can also input data and store it on your laptop using a floppy disk. The floppy drive can be an internal part of the laptop. Some laptops have floppy drives connected externally by cables.
	19.4.6 CD and DVD Drives
	The CD and DVD drives on the laptop enable data transfer to CDs and DVDs. You can also store data on CDs and DVDs from the laptop. Some laptops have a single bay where you can interchange the drive inserted in the bay. Other laptops can have multiple bays for different drives. There are certain laptops that have no bay in the structure. Such laptops are designed this way to keep the size and weight of the laptop to a minimum. Figure 19.5 displays a CD drive on a laptop.
	19.4.7 Batteries
	All laptops have batteries as an alternate source of power. Laptops are portable because they are powered by batteries. The different types of batteries used by laptops include nickel-cadmium, lithium ion and nickel-metal hydride. Nickel cadmium batteries were in wide use previously. They offered good output at a low cost to the earlier laptop users. However, the lithium ion and nickelmetal hydride batteries are popular presently. Nickel-metal hydride batteries were introduced with several improvements over the nickel cadmium batteries. However, both nickel-cadmium and nickel-metal hydride batteries have a drawback called the memory effect. Memory effect is the reduction of power storing capability of a battery, which occurs when the battery is recharged before it is fully discharged. The lithium ion batteries offer improvements in capacity and reduction of memory effect. The lithium ion batteries are therefore the most popular version of laptop batteries presently. Batteries have different life spans depending on the amount of usage and the type of battery. Laptops have inbuilt power management software that helps to extend the lifetime of the battery. When the battery is low, the power management software makes the laptop function slowly. This acts as a signal to the user to recharge the battery or connect the laptop to the power supply socket.
	19.4.8 Device card (PCMCIA card)
	The PCMCIA card is a memory or I/O device that is about the size of a credit card. The PCMCIA card connects to the laptop. The card then connects to a device such as a fax, modem or memory device. PCMCIA stands for Personal Computer Memory Card International Association, which is a foundation that developed a standard for device cards. As a result, laptop users can be assured of a standard attachment for all devices that follow the PCMICIA standard. The PCMCIA card has a 68-pin connector that connects to a slot on a laptop. The different types of PCMCIA cards are: _ Type I - Used mostly for connecting to memory devices. These cards are about 3.3 mm. thick. _ Type II - Typically connects to a modem, a SCSI device or a sound device. These cards are about 5.5 mm. thick. _ Type III - Used to connect to hard drives. These cards are about 10.5 mm. thick. The different types of cards have slots of corresponding sizes. The Type I slot can accommodate only one Type I card. The Type II slot can hold a single Type I or Type II card. The Type III slot can accommodate a single Type III card. It is possible to simultaneously connect any combination of two Type I and Type II cards in a Type III slot.
	19.4.9 Infrared ports
	The infrared ports on laptops enable the laptop to communicate with other devices without using cables or wires. Thus, the infrared ports enable wireless communication between laptops and other devices. The infrared ports communicate and transmit data using infrared light waves. This is somewhat similar to the way a TV remote communicates with the TV. The device that the infrared port communicates with must have a corresponding infrared port. If you have a printer that has an infrared port, it can communicate with your laptop without cables. You can print documents by placing the printer and laptop opposite each other, with their infrared ports facing each other. However, the two communicating devices must be within a few feet of each other and the path between them must be clear of any intrusions. Figure 19.6 displays the PCMCIA port and infrared LAN port on a laptop. PCMCIA Port Infrared LAN Port
	19.4.10 I/O Ports
	The laptop connects and communicates with other devices with the help of the I/O ports. The different I/O ports on a laptop are: _ Power socket - Connects to the AC adapter card, which connects to the power socket. _ Modem socket - Connects to the modem for making dial-up connections to the network. _ Network socket - Connects to the network cable. _ Microphone socket - Connects to a microphone for audio input. _ Headphone socket - Connects to the headphone for audio output. _ Parallel port - Used to connect to devices such as printers or scanners. _ Serial port - Connects to devices such as modems and mice. _ USB ports - Connect to devices such as floppy drives or CD-ROM drives. _ S Video port - Enables output of video to the monitor or another screen. _ Monitor port - Connects to the monitor of the laptop. _ Firewire port - Enables connections to different devices. Figure 19.7 displays the different ports on the back of a laptop. Figure 19.7 - Ports on a Laptop 19.4.11 A/C Adapters The AC adapter supplies power to the laptop. The AC power from the power socket is converted into DC power, which can be used by the laptop. Figure 19.8 - AC Adapter Monitor Power S Video Parallel Network Modem USB Headphone Microphone
19.5 Laptop Input and Output Devices
	The different input and output devices of the laptop enable users to store data in the laptop and also to access and retrieve information. The keyboard, display, and pointer devices are the main input and output means of a laptop.
	19.5.1 Keyboard
	The keyboards of laptops are generally small in size and mostly have additional features that enhance user comfort. Laptops generally do not use ergonomic keyboards. The locations of the keys will also be different as compared to a desktop keyboard. All laptop keyboards will not have the numeric keypad.
	19.5.2 Touch Pad
	Touch pads are very common input devices for laptops. These devices are a little larger than credit cards. A touch pad responds to movements of the hand on its surface. You can drag your fingers and tap them on the touch pad to move the cursor on the screen. Touch pads are very easy to use and are highly accurate.
	19.5.3 Trackpoint
	The trackpoint is a small button located between the keys on the laptop keyboard. You can move the cursor on the screen by pushing the point around with your fingers.
	19.5.4 Display Screen
	The display screens on all laptops use Liquid Crystal Display (LCD) technology. Laptop displays are generally between 12 to 17 inches in dimension. The display can be grayscale or color. Laptop displays generally have resolutions of 640 x 480 pixels and higher.
19.6 Troubleshooting
	You can come across many problems on your laptop, the cause of which can be software or hardware. You must systematically follow troubleshooting steps to detect the cause of the problem and repair it.
	Best practice
	1. Check all cable connections. 2. Verify whether the power is turned on. 3. Do not use the laptop in a hot environment. 4. Always store data backups in floppy disks or CDs. 5. Handle the laptop gently and with a lot of care. 6. If you are traveling, ensure that the laptop battery is not empty.
	Precautions
	1. Turn off the laptop and disconnect it before performing any troubleshooting. 2. Wear an anti-static wristband.
	19.6.1 Laptop does not start after being turned on
	Sometimes the laptop will not start working after being turned on. This is most probably a power supply problem. It can also be a result of overheating. 1. If you are using a battery, inspect it to verify whether it needs recharging. If it does, recharge the battery after fully discharging it first. 2. Check the connection of the power cable to the socket. The connection must be tight. 3. Check the AC adapter. If the light on the AC adapter is not on, it is not working properly and must be replaced. 4. If the power indicator shows a blinking orange light, the laptop has probably shut down because of overheating. 5. Check the output vent of the laptop to see if the fan is working. 6. See if there is any dust covering the output vent. 7. Clean the dust carefully with a soft dry cloth. 8. Allow the laptop to cool down and then restart it. _ You can find out if your battery needs a recharge or replacement by turning off the AC power. If the laptop shuts down totally, the battery needs recharging. If your battery remains cool to the touch after an hour or more of recharging, it will have to be replaced.
	19.6.2 Ctrl+Alt+Delete does not Work
	Sometimes the Ctrl+Alt+Delete command does not work. If your laptop doesn't restart after you press these keys twice, there is a problem with your system. 1. Press the power button and turn off the laptop. 2. Restart the laptop and check the keyboard lights to see if the keyboard is recognized. Press the Num Lock or Caps Lock key to verify this. 3. If the keyboard is being recognized, contact the manufacturer. 4. If the keyboard is not recognized, connect another compatible keyboard to the laptop. If the laptop does not recognize the keyboard device, contact the manufacturer. 5. Check Event Viewer details to see if an error has been logged. 6. Run the Antivirus Program to detect a virus or Trojan horse in the system
	19.6.3 Printer does not work
	Printers are very important output devices. If the printer does not function properly, it could be the result of a hardware or configuration problem. 1. Check the printer light to see if it is on. 2. Check the cable connections on the printer as well as on the laptop. The connections must be secure. 3. If the printer is infrared, ensure that there are no obstacles between the infrared ports. 4. If the printer is blinking, refer to the manual to find out the cause of the problem. 5. Replace the printer with another compatible one. If this printer works, the laptop does not have any problem. 6. Ensure that the printer is set to Default Printer. 7. Go to Device Manager and check whether the printer driver is installed properly. 8. Press Delete when the laptop is starting up. This will take you to the CMOS setup. Check whether the printer port is enabled and working properly. 9. Ensure that the printer mode is not set to ECP. This mode can make the printer malfunction. 10. Run the printer self-test. If it fails, the printer is faulty and not the laptop.
	19.6.4 Laptop Keyboard gets Wet
	You must be very careful not to let any liquid spill onto the laptop keyboard. If the keyboard gets wet, it could cause serious damage to the keyboard as well as the laptop. 1. Shut down the laptop and remove the battery. 2. Unplug the keyboard and remove it. 3. Let all the liquid drain out of the keyboard. 4. Clean the keyboard with cotton swabs. 5. Clean the underside of the keys with an air blower/vacuum cleaner. Be careful to hold the nozzle at a proper angle. 6. Turn the laptop upside down very carefully, without damaging the display. Leave the laptop in this position for at least 48 hours before turning it on. 7. Plug in the keyboard and check if it is working. 8. If the keyboard does not work, it will have to be replaced.
	19.6.5 CD/DVD Drive problem
	Sometimes you may get a message like drive is not accessible or device is not ready, when you try to access your CD or DVD drive. This may occur even if the Device Manager does not show any fault. 1. Ensure that the connection to the drive is secure and the disk is properly inserted in the drive. 2. Check the surface of the disk for dirt or abrasions. 3. Clean the drive with a cleaning disk. 4. Try playing other disks in the drive. If no disk plays, there is a problem with the drive. 5. Try to access the drive after restarting the laptop.