Computer harware complete notes

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These are the complete notes of computer hardware which are usefull in project reports & synopsis while submitting also help in studying.provided by the technical zone

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Computer harware complete notes

  1. 1. 1|PageINTRODUCTION TO COMPUTER STRUCTURE & FUNCTIONALITY:Let us start us with a term ComputerCOMPUTER stands for:C-commono-operatingm-machinep-particularlyu-used fort-technicale-education andr-researchDisplay DevicesA computeris a computing device made up of many distinct electronic components that all functiontogether in order to accomplish some useful task (such as adding up the numbers in a spreadsheet orhelping you write a letter). By this definition, note that we’re describing a computer as having manydistinct parts that work together.. Each component has a very specific function. The Technical Zone
  2. 2. 2|PageNow we will learn how to identify computer components, includingthe following:Motherboards Storage devicesPower supplies Display devicesInput devices Adapter cardsPorts and cables ProcessorsMemoryAny PC is a complex machine. It could be described as a melting pot of various technologies and products,manufactured by a host of companies in many different countries. This diversity is a great advantagebecause it gives the PC its versatility. However, these components don’t always “melt” together into aunified whole without the help of a technician. The different products—whether they’re hard disks,modems, sound cards, or memory boards—must share one processor and one motherboard and thereforemust be designed to work in harmony.The whole computer system is categorized into four main components:INPUT DEVICES :( Keyboard, mouse, scanner, joystick, Digital camera)Central Processing Unit :( Control Unit, Arithmetic and Logical Unit)MEMORY :( Primary and Secondary memory)OUTPUT DEVICES :( Monitor, Printer, plotter, speakers)Introduction to computer peripherals:Input devices: All devices those helps us to sent commands and data to the computer such as Keyboard :-keyboard is easily the most popular input device, so much so that its popularity is more of a necessity. The keys on a keyboard complete individual circuits when each one is pressed. The completion of each circuit leads to a unique scan code that is sent to the keyboard connector on the computer system. The computer uses a keyboard controller chip to interpret the code as the corresponding key sequence. The computer then decides what action to take based on the key sequence and what it means to the computer and the active application. The Technical Zone
  3. 3. 3|Page Mouse:-Computer mouse was born in the 1970s at Xerox’s Palo Alto Research Center (PARC), it was Apple in 1984 that made the mouse an integral part of the personal computer image with the introduction of the Macintosh. Many variations of the mouse exist, including:- trackballs, tablets, touchpads, and pointing sticks.The mouse today can be wired to the computer system or wireless. Wireless versions use batteries to power them, and the optical varieties deplete these batteries more quickly thantheir mechanical counterparts.Mechanical Mouse Optical MouseThe motion-detection mechanism of the original technologies used optical receptors to catch LED lightmouse was a simple ball that protruded from the reflected from specially made surfaces purchased withbottom of the device so that when the bottom the devices and used like a mouse pad. A mouse pad iswas placed against a flat surface that offered a a special surface to improve mechanical mouseslight amount of friction, the mouse would glide traction while offering very little resistance to theover the surface, but the ball would roll, actuating mouse itself. As optical science advanced for thetwo rollers that mapped the linear movement to mouse, lasers were used to allow a sharper image tothe software interface. be captured by the mouse and more sensitivity in motion detection. Bar-code Reader:A bar-code reader (or bar-code scanner) is a specialized input device commonly used in retail and other industrial sectors that manage inventory. Bar-code readers can use LEDs or lasers as light sources and can scan one- or two-dimensional bar-codes. Bar-code readers can connect to the host system in a number of ways, but serial connections, such as RS-232 and USB are fairly common. The scanner converts all output to keyboard scans so that the system treats the input as if it came from a keyboard. For certain readers, wireless communication with the host is also possible, using IR, RF, Bluetooth, Wi-Fi, and more. Touch Screens:Touch-screen technology converts stimuli of some sort, which are generated by actually touching the screen, to electrical impulses that travel over serial connections to the computer system. These input signals allow for the replacement of both the keyboard and the mouse. However, standard computer systems are not the only application for touch-screen enhancement. This technology can also be seen in PDAs, point-of-sale venues for such things as PIN entry and signature capture, handheld and bar-mounted games, ATMs, remote controls, appliances, and vehicles. For touch screens there are a handful of solutions for how to convert a touch to a signal. Some less-successful ones rely on warm hands, sound waves, or dust-free screens. The more successful screens have optical or electrical sensors that are quite a bit less fastidious. In any event, the sensory system is added onto a standard monitor at some point in the creation of the monitor. Scanner:-scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. The Technical Zone
  4. 4. 4|Page Microphone:-is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production, live and recorded audio engineering, FRS radios, megaphones, in radio and television broadcasting and in computers for recording voice, speech recognition, VoIP, and for non-acoustic purposes such as ultrasonic checking or knock sensors.Output Devices:-Display Devices:CRT (Cathode ray tube) LCD (Liquid Cristal display) Plasma DisplayIn a CRT, a device called Two major types of LCDs are used in laptops They are called "plasma" displaysan electron gun shoots today: active matrix screens and passive because the pixels rely on plasmaelectrons toward the matrix screens. cells, or what are in essence chambersback of the monitor Passive matrix A passive matrix screen uses more commonly known as fluorescentscreen . The back of the a row of transistors across the top of the lamps. A panel typically has millions ofscreen is coated with screen and a column of them down the side. tiny cells in compartmentalized spacespecial chemicals It sends pulses to each pixel at the between two panels of glass. These(called phosphors) that intersections of each row and column compartments, or "bulbs" or "cells",glow when electrons combination, telling it what to display. hold a mixture of noble gases and astrike them. This beam Passive matrix displays are becoming minuscule amount of mercury. Just asof electrons scans the obsolete because they’re less bright and in the fluorescent lamps over an officemonitor from left to have poorer refresh rates and image quality desk, when the mercury is vaporizedright than active matrix displays. However, they and a voltage is applied across the use less power than active matrix displays cell, the gas in the cells form a plasma. do. With flow of electricity (electrons), some of the electrons strike mercury Active matrix An active matrix screen uses a particles as the electrons move separate transistor for each individual pixel through the plasma, momentarily in the display, resulting in higher refresh increasing the energy level of the rates and brighter display quality. These molecule until the excess energy is screens use more power, however, because shed. Mercury sheds the energy as of the increased number of transistors that ultraviolet (UV) photons. Varying the must be powered. Almost all notebook PCs voltage of the signals to the cells thus today use active matrix. A variant called allows different perceived colors. thin-film transistor (TFT) uses multiple transistors per pixel, resulting in even better display quality.Display systems convert computer signals into text and pictures and display them on a televisionlikescreen. Several different types of computer displays are used today, including the TV.Ways of measuring amonitor’s image quality: dot pitch and refresh (scan) rate. A monitor’s dot pitch is the distance betweentwo dots of the same color on the monitor. Usually given in fractions of a millimeter (mm), it tells howsharp the picture is. The lower the number, the closer together the pixels are, and thus the sharper theimage. An average dot pitch is 0.28mm. A monitor’s refresh rate specifies how many times in one second The Technical Zone
  5. 5. 5|Pagethe scanning beam of electrons redraws the screen. The phosphors stay bright for only a fraction of asecond, so they must constantly be hit with electrons to stay lit. Given in draws per second, or hertz (Hz),the refresh rate specifies how much energy is being put into keeping the screen lit. Most people notice aflicker in the display at refresh rates of 75Hz or lower because the phosphors begin to decay to blackbefore they’re revived; increasing the refresh rate can help reduce eyestrain by reducing the flickering. Theresolution of a monitor is the number of horizontal and vertical pixels that are displayed. Most monitorsallow for two or more resolutions, and you can pick the one to use in the desktop settings of the operatingsystem. The vertical hold (V-hold) settings can be tweaked to make the image appear properly in themonitor.Display System Problems:-There are two types of video problems: no video and bad video. No video means no image appears on thescreen when the computer is powered up. Bad video means the quality is substandard for the type ofdisplay system being used.Connector Types:The following are common connector types: DB A D-shaped connector with a metal ring around a set ofpins. Named for the number of pins/holes used: DB-25, DB-9, DB-15, and so on. Can be either parallel orserial. Common uses: VGA video, legacy serial devices such as external modems, and parallel printer cables(the connector on the PC only; the printer end uses Centronics). RJ Registered jack : a plastic plug with small metal tabs, like a telephone cord plug. Numbering is used in the naming: RJ-11 has two metal tabs, and RJ-14 has four. Both are used for telephone systems. RJ-45 has eight tabs and is used for Ethernet 10BaseT/100BaseT networking. Always serial. BNC Stands for Bayonet:-Neill Connector or British Naval Connector. A metal wire surrounded by shielding, like a cable television connector. Used for 10Base2 Ethernet networking. Always serial. Centronics:A plastic block with metal tabs flat against it, surrounded by a D-shaped metal ring. Used to connect a parallel printer cable to the printer, and also for some SCSI devices. Always parallel. Ribbon connector:A rectangular block consisting of a set of square holes that connect to pins on a circuit board. Used to connect floppy drives, IDE drives, and some SCSI devices to their controllers. Always parallel. The Technical Zone
  6. 6. 6|Page PS/2 (mini-DIN)A round connector with six small pins inside, commonly used to connect keyboards on ATX motherboards or PS/2 style mice. DIN:A larger round connector with five rather large pins inside, used for connecting the keyboard on an AT motherboard. USB:A flat rectangular connector, used with USB interfaces.Cabling:Cables are used to connect two or more entities together. They’re usually constructed of several wiresencased in a rubberized outer coating. The wires are soldered to modular connectors at both ends. Theseconnectors allow the cables to be quickly attached to the devices they connect. Cables may be eithershielded or unshielded. This refers to shielding against electromagnetic interference (EMI); it has nothingto do with whether the cable is shielded against dirt or water. A is given in The F or M in a connector’sdesignation is for female (holes) or male (pins). Common PC Cable list of common cable types used inPCs, their descriptions, their maximum effective lengths, and their most common uses The Technical Zone
  7. 7. 7|PageFans: When you turn on a computer, you will often hear lots of whirring. Contrary to popular opinion, themajority of the noise isn’t coming from the hard disk (unless it’s about to go bad). Most of this noise iscoming from the various fans inside the computer. Fans provide airflow within the computer.Introduction to printers:Impact Printers: The most basic type of printer is the category known as impact printers . Impact printers,as their name suggests, use some form of impact and an inked ribbon to make an imprint on the paper. Ina manner of speaking, typewriters are like impact printers. Both use an inked ribbon and an impact head tomake letters on the paper. The major difference is that the printer can accept input from a computer.There are two major types of impact printers: daisy wheel and dot matrix. Each type hasits own service andmaintenance issues.Dot-Matrix Printers: The other type of impact printer we’ll discuss is thedot-matrix printer. These printersworkin a manner similar to daisy-wheel printers, but instead of a spinning, character-imprinted wheel, theprint head contains a row of pins(short, sturdy stalks of hard wire). These pins are triggered in patterns that form letters and numbers asthe print head moves across the paper The Technical Zone
  8. 8. 8|PageBubble-Jet Printers:The next category of printer technology is one of the most popular in use today. This category is actually anadvanced form of an older technology known asinkjet printers. Both types of printers spray ink on thepage, but inkjet printers used a reservoir of ink, a pump, and an inknozzle to accomplish this. They weremessy, noisy, and inefficient. Bubble-jet printers workmuch more efficiently and are much cheaper.Inabubble-jet printer,bubbles of ink are sprayed onto a page and form patterns thatresemble the items beingprinted. In this section, you will learn the parts of a bubble-jet printer, as well as how bubble-jet printerswork.Laser Printers:Laser printers and inkjet printers are referred to as page printers because they receive theirprint job instructions one page at a time (rather than receiving instructions one line at a time). There aretwo major types of page printers: those that use the electro photographic (EP) print process and those thatuse the light-emitting diode (LED) print process. Each works in basically the same way, with slightdifferences. The Technical Zone
  9. 9. 9|PagePrint head/Ink Cartridge:The first part of a bubble-jet printer is the one people see the most: the print head. This part of a printercontains many small nozzles (usually 100–200) that spray the ink in small dots onto the page. Many timesthe print head is part of the ink cartridge, which contains a reservoir of ink and the print head in aremovable package. Color bubble-jet printers include multiple print heads, one for each of the CMYK printinks (cyan, magenta, yellow, and black).Daisy-Wheel Printers:Although they aren’t really covered on the A+ exam, the first type of impact printer we’re going todiscuss is the Daisy-wheel printer. These printers contain a wheel (called the because it looks like a daisy) with raised letters and symbols on each “petal” (see Figure 7.1). When thePrinter needs to print a character; it sends a signal to the mechanism that contains the wheel. ThisMechanism is called the printheaddaisy wheel. The printhead rotates the daisy wheel until the requiredcharacter is in place. An electromechanical hammer (called a ) then strikes the back of the petal Containingthe character. The character pushes up against an inked ribbon that ultimately strikes The paper, making theimpression of the requested character. :: The Technical Zone
  10. 10. 10 | P a g e The Technical Zone
  11. 11. 11 | P a g eIntroduction to motherboard and all its components:Motherboards:The motherboard is the backbone of a computer. The components of the motherboard provide basicservices needed for the machine to operate and provide a platform for devices such as the processor,memory, disk drives, and expansion devices. For this objective, you should study the types ofmotherboards, their ports and memory, the types of CPU sockets, and the types of expansion slots.Components on a motherboard:System Board Form Factors:Form factor refers to the size and shape of a component. There are four popular motherboard form factorsfor desktop PCs: AT, ATX, BTX, and NLX.AT ”AT” is an older style of motherboard. A slightly more modern variant of it is the baby AT, which issimilar but smaller. Its key features are a two-piece power-supply connector, ribbon cables that connectthe I/O ports to the board, and an AT-style keyboard connector. The expansion slots are parallel to thewide edge of the board. The Technical Zone
  12. 12. 12 | P a g eATX:Most system boards today use the ATX form factor. It contains many design improvements over theAT, including I/O ports built directly into the side of the motherboard, the CPU positioned such that thepower-supply fan helps cool it, and the ability for the PC to be turned on and off via software. It uses aPS/2 style-connector for the keyboard. The expansion slots are parallel to the narrow edge of the board.BTX the Balanced Technology Extended (BTX) motherboard was designed by Intel to deal with issuessurrounding ATX (heat, power consumption, and so on). The BTX motherboard is larger than ATX, so thereis more room for integrated components; there is also an optimized airflow path and a low-profile option.Although the standard has been around for a number of years, it isn’t expected to become popular in themarket until at least 2007.NLXAn acronym for New, Low profile extended, this form factor is used in low-profile case types. Itincorporates expansion slots that are placed on a riser board to accommodate the reduction in case size.However, this design adds another component to troubleshoot.Buses: A bus is a set of signal pathways that allows information and signals to travel between componentsinside or outside a computer. A motherboard has several buses, each with its own speed and width.The external data bus, also called the system bus, connects the CPU to the chipset. On modern systems, it’s64-bit. The address bus connects the RAM to the CPU. On modern systems, it’s 64-bit. The expansion busconnects the I/O ports and expansion slots to the chipset. There are usually several different expansionbuses on a motherboard. Expansion buses can be broken into two broad categories: internal and external.Internal expansion buses include Industry Standard Architecture (ISA), Peripheral Component Interconnect(PCI), and Accelerated Graphics Port (AGP); they’re for circuit boards. External expansion buses includeserial, parallel, Universal Serial Bus (USB), FireWire, and infrared. The following sections explain some ofthe most common buses.ISA: This is a 16-bit bus (originally 8-bit on the oldest computers) that operates at 8MHz. Its slots areusually black. New motherboards may not have this type of slot, because the ISA bus is old technology andis being phased out. Besides the slow speed and narrow width, another drawback of the ISA bus is thateach ISA device requires separate system resources, including separate Interrupt Requests (IRQs). In aheavily loaded system, this can cause an IRQ shortage. (PCI slots, in contrast, can share some resources.) The Technical Zone
  13. 13. 13 | P a g ePCIThe PCI bus is a fast (33MHz), wide (32-bit or 64-bit) expansion bus that is the modern standard inmotherboards today for general-purpose expansion devices. Its slots are typically white. PCI devices canshare IRQs and other system resources with one another in some cases. All modern motherboards have atleast three PCI slots. Figure 1.6 shows some PCI slots.AGPAs systems got faster, PC game players wanted games that had better graphics, more realism,and morespeed. However, as the computers got faster, the video technology couldn’t seem tokeep up, even withthe PCI bus. The AGP bus was developed to meet this need.The AGP slot is usually brown, and there is onlyone. It’s a 32-bit or 64-bit bus, and it runsvery fast (66MHz or faster). It’s used exclusively for the videocard. If you use a PCI video card, the AGP slot remains empty.PCIEPCI Express (PCIE , PCI-E, or PCIe) uses a network of serial interconnects that operate at highspeed. It’sbased on the PCI system; most existing systems can be easily converted to PCIE.Intended as a replacementfor AGP and PCI, PCIEhas the capability of being faster than AGP,while maintaining the flexibility of PCI.There are currently six different speed levels and theycorrespond to AGP speeds: 1X, 2X, 4X, 8X, 16X, and32X.AMR AND CNRAudio Modem Riser (AMR) was originally created to speed manufacturing (and certification) by separatingthe analog circuitry (modem and analog audio) onto its own card. Over time,this has been replaced by CNR(CommunicationsNetwork Riser), which includes the capabilitiesof AMR and allows the motherboardchipset to be designed with additional integratedfeatures.Identifying Purposes and Characteristics of Adapter Cards The Technical Zone
  14. 14. 14 | P a g eAn adapter card (also known as an expansion card) is simply a circuit board you install into a computer toincrease the capabilities of that computer. Adapter cards come in many different kinds, but the importantthing to note is that no matter what function a card has, the card being installed must match the bus typeof the motherboard you are installing it into (for example, you can install a PCI network card only into a PCIexpansion slot). Five of the most common expansion cards that are installed today are as follows:_ Video card_ Network interface card (NIC)_ Modem_ Sound card_ I/O cardVideo CardA video adapter (more commonly called a video card) is the expansion card you put into a computer inorder to allow the computer to display information on some kind of monitor or LCD display. A video cardalso is responsible for converting the data sent to it by the CPU into the pixels, addresses, and other itemsrequired for display. Sometimes, video cards can include dedicated chips to perform certain of thesefunctions, thus accelerating the speed of display. With today’smotherboards, most video cards are AGP and, with increasing popularity, PCIe expansion cards that fit inthe associated slot on a motherboard. Figure 1.51 shows an example of an AGP-based video card.A video expansion cardNetwork Interface Card (NIC)A network interface card (NIC) is an expansion card that connects a computer to a network so that it cancommunicate with other computers on that network. It translates the data from the parallel data streamused inside the computer into the serial data stream of packets used on the network. It has a connector forthe type of expansion bus on the motherboard (PCIe, PCI, ISA, and so on) as well as a connector for thetype of network (such as RJ-45 for UTP or BNC for coax). In addition to the NIC, you need to install softwareor drivers on the computer in order for the computer to use the network. The Technical Zone
  15. 15. 15 | P a g eA network interface card (NIC)ModemAny computer that connects to the Internet using a dial-up connection needs a modem. A modem is adevice that converts digital signals from a computer into analog signals that canbe transmitted over phonelines and back again. These expansion card devices have one connector for the expansion bus being used(PCIe, PCI, ISA, and so on) and another for connection to the telephone line. there are two RJ-11 ports: onefor connection to the telephone line and the other for connection to a telephone. This is the case primarilyso that putting a computer online still lets someone hook a phone to thatwall jack (although he won’t beable to use the phone while the computer is connected to the Internet). AN INTERNAL MODEMSound CardJust as there are devices to convert computer signals into printouts and video information, there aredevices to convert those signals into sound. These devices are known as sound cards. Many differentmanufacturers make sound cards, but the standard has been set by Creative Labs with its SoundBlasterseries of cards.I/O CardI/O card is often a catchall phrase for any adapter card that expands the system to interface with devicesthat offer input to the system, output from the system, or both. Common examples of I/ O are the serialand parallel ports of the system, drive interface connections, and so on. A very popular expansion card ofthe 1980s and early 1990s was known as the Super I/O card. This one adapter had the circuitry for twostandard serial ports, one parallel port, two PATA controllers, and one floppy controller. Some versionsincluded more still. For many years, if you wanted to use a SCSI hard drive in your system, you had toinstall an adapter card that expanded the motherboard’s capabilities to allow the use of SCSI hard drives.The drives would them cable to the adapter, and the adapter would perform the requisite conversion of The Technical Zone
  16. 16. 16 | P a g ethe drive signals to those that the motherboard and the circuits installed on it could use. Today, commonI/O adapter cards tend to be USB 2.0 adapters and FireWire adaptersUnderstanding Printer andScanner FundamentalsThere are several different types of printers and scanners available on the market today. In this section,you will learn about the different types of printers and scanners that you will see as a technician, theirbasic components, and how they function.LEGACY PARALLEL AND SERIALThese buses are called legacy because they’re old technology and are being phased out. Thelegacy serialport, also called an RS-232 port, is a 9-pin or 25-pin male connector. It sends dataone bit at a time and isusually limited to about 115Kbps in speed.The legacy parallel port transfers data 8 bits at a time. It’s a 25-pin female connector. A systemtypically has only one parallel port, but because many printers are nowcoming with USBinterfaces, this is no longer the inconvenience that it used to be.USBUSB is a newer expansion bus type that is used almost exclusively for external devices. Allmotherboardstoday have at least two USB ports. Some of the advantages of USB include hotpluggingand the capabilityfor up to 127 USB devices to share a single set of system resources.USB 1.1 runs at 12Mbps, and USB 2.0runs at 480Mbps. Because USB is a serial interface, itswidth is 1 bit.IEEE 1394/FIREWIRESome newer motherboards have a built-in IEEE 1394/FireWire port, although this port ismore typicallyfound on a PCI expansion board. It transfers data at 400Mbps and supports upto 63 chained devices on asingle set of resources. It’s hot pluggable, like USB. Figure 1.8shows the connections on a FireWire card.Daughterboard The Technical Zone
  17. 17. 17 | P a g e(“daughters” of the “mother”). A common use is to insert one daughterboard (also calledAny boards addedto the motherboard to expand its capabilities are known as daughterboardsdaughter boards) into themotherboard and allow expansion cards to then be inserted into itsideways, thus saving space.On-Motherboard CacheOn older motherboards, the L2 cache is on its own RAM-like stick made of very fast static randomaccessmemory (SRAM). It’s known as cache on a stick (COAST). On newer systems, theL2 cache is built into theCPU packaging.Some newer systems also have an L3 cache, which is an external cache on the motherboardthat sits between the CPU and RAM.IDE and SCSI On-Motherboard InterfacesMost motherboards include two Integrated Drive Electronics (IDE) channels but don’t includebuilt-in SmallComputer System Interface (SCSI). A consideration when choosing a motherboard for IDE is that it needs tosupport the desired level of UltraDMA to match the capabilities of thehard drive you want to use.ChipsetsThe chipset is the set of controller chips that monitors and directs the traffic on the motherboardbetweenthe buses. It usually consists of two or more chips. Motherboards use two basicchipset designs: thenorth/south bridge chipset and the hub chipset.North/south bridge is the older of the two. The northbridge connects the system bus to theother relatively fast buses (AGP and PCI). The south bridge connectsISA, IDE, and USB. Athird chip, SuperIO, connects the legacy parallel and serial ports.The hub chipsetincludes a memory controller hub (equivalent to the north bridge), an I/Ocontroller hub (equivalent to thesouth bridge), and a SuperIO chip.CMOSYou can adjust a computer’s base-level settings through a Basic Input/Output System (BIOS)Setup program,which you access by pressing a certain key at startup, such as F1 or Delete(depending on the system).Another name for this setup program is CMOS Setup. The mostcommon settings to adjust in CMOS include The Technical Zone
  18. 18. 18 | P a g eport settings (parallel, serial, USB), drive types,boot sequence, date and time, and virus/securityprotections.ACCESSING CMOS SETUPYour PC keeps these settings in a special memory chip called the Complementary MetallicOxideSemiconductor (CMOS) chip. The CMOS chip must have a constant source of powerto keep its settings. Toprevent the loss of data, motherboard manufacturers include a smallbattery to power the CMOS memory.On modern systems, this is a coin-style battery, aboutthe same diameter of a dime and about 1/4 inch thick.You can press a certain key or group of keys toaccess the setup program during the poweron self-test (POST). This utility allows you to change theconfiguration through a group ofmenus. There are many different CMOS Setup programs, depending onthe BIOS make andmanufacturer, so it’s impossible to provide specifics here; instead, we’ll look atcapabilities.LOAD SETUP DEFAULTSThe purpose of this setting is to configure the PC back to the default settings set by the factory.If you makechanges to your settings and the machine becomes disabled, in most cases, selectingthis menu itemreturns the machine to a usable state. You may then try different settingsuntil you achieve your desiredconfiguration. This is an important setting to know aboutbefore making any other changes.DATE AND TIMEOne of the most basic things you can change in CMOS Setup is the system date and time. Youcan alsochange this from within the operating system.CPU SETTINGSIn most modern systems, the BIOS detects the CPU’s type and speed automatically, so anyCPU setting inCMOS Setup is likely to be read-only.MEMORY SPEED/PARITYMost systems today detect the RAM amount and speed automatically. Some motherboardscan usedifferent types of RAM, such as parity and nonparity, or different speeds, and theCMOS Setup program The Technical Zone
  19. 19. 19 | P a g emay provide the opportunity to change those settings. Increasingly,however, RAM is becoming a read-onlypart of CMOS Setup programs.POWER MANAGEMENTThe Power Management settings determine the way the PC will act after it has been idle forcertain timeperiods. For example, you may have choices like Minimum, Maximum, and UserDefined. The Minimum andMaximum settings control the HDD Off After, Doze Mode,Standby Mode, and Suspend Mode settings withpredefined parameters. If you select UserDefined, you must manually configure these settings to yourpersonal preferences.NorthbridgeThe Northbridge subset of a motherboard’s chipset is the set of circuitry or chips that performs one veryimportant function: management of high-speed peripheral communications. The Northbridge subset isresponsible primarily for communications with integrated video using AGP and PCIe, for instance, andprocessor-to-memory communications. Therefore, it can be said that much of the true performance of aPC relies on the performance of the Northbridgechipset and the communications between it and the peripherals it controls.SouthbridgeThe Southbridge chipset, as mentioned earlier, is responsible for providing support to the myriad onboardperipherals (PS/2, Parallel, IDE, and so on), managing their communications with the rest of the computerand the resources given to them. Most motherboards today have integrated PS/2, USB, Parallel, and Serial.Some of the optional features handled by the Southbridge include LAN, audio, infrared, and FireWire (IEEE1394). When first integrated, the quality of onboard audio was marginal at best, but the latest offerings(such as the AC97 audio chipset) rival Creative Labs in sound quality and number of features (evenincluding Dolby Digital Theater Surround technology). The Southbridge chipset is also responsible formanaging communications with the other expansion buses, such as PCI, USB, and legacy busesA typical motherboard chipset The Technical Zone
  20. 20. 20 | P a g eIntroduction to processors.Processor/CPUsThe central processing unit (CPU) is a processor chip consisting ofan array of millions of integratedcircuits. Its purpose is to accept,perform calculations on, and eject numeric data. It’sconsideredthe “brain” of the computer because it’s the part that performs the mathematicaloperations required forall other activity.There are two form factors for CPU chips: pin grid array (PGA) and single edge contact cartridge(SECC). ThePGA style is a flat square or rectangular ceramic chip with an array of pinsin the bottom. The actual CPU isa tiny silicon wafer embedded inside that ceramic chip. TheSECC style is a circuit board with the siliconwafer mounted on it. The circuit board is thensurrounded by a plastic cartridge for protection; the circuitboard sticks out of the cartridgealong one edge. This edge fits into a slot in the motherboard.All CPUs today require cooling because theygenerate heat as they operate. The cooling canbe either active or passive. A passive heat sink is a block ofheat-conductive material that sitsclose to the CPU and wicks away the heat into the air. An active heat sinkcontains a fan thatpulls the hot air away from the CPU.External Speed (Clock Speed)The clock speed, or external speed, is the speed at which the motherboard communicates withthe CPU. It’sdetermined by the motherboard, and its cadence is set by a quartz crystal (the systemcrystal) thatgenerates regular electrical pulses.Internal SpeedThe internal speed is the maximum speed at which the CPU can perform its internal operations.This may bethe same as the motherboard’s speed (the external speed), but it’s morelikely to be a multiple of it. Forexample, a CPU may have an internal speed of 1.3GHz butan external speed of 133MHz. That means forevery tick of the system crystal’s clock, the CPUhas 10 internal ticks of itsown clock. The Technical Zone
  21. 21. 21 | P a g eCache MemoryA cache is an area of extremely fast memory used to store data that is waiting to enter or exitthe CPU. TheLevel 1 cache, also known as the L1 or front-side cache, holds data that is waitingto enter the CPU. Onmodern systems, the L1 cache is built into the CPU. The Level 2cache, also known as the L2 or back-sidecache, holds data that is exiting the CPU and is waitingto return to RAM. On modern systems, the L2 cacheis in the same packaging as the CPUbut on a separate chip. On older systems, the L2 cache was on aseparate circuit board installedin the motherboard, and was sometimes called COAST.The BusThe processor’s ability to communicate with the rest of the system’s components relies onthe supportingcircuitry. The system board’s underlying circuitry is called the bus. The computer’sbus moves informationinto and out of the processor and other devices. A bus allowsall devices to communicate with each other.The motherboard has several buses. The externaldata bus carries information to and from the CPU and isthe fastest bus on the system.The address bus typically runs at the same speed as the external data busand carries datato and from RAM. The PCI, AGP, and ISA interfaces also have their own buses withtheirown widths and speeds.The CPU must be compatible with the motherboard in the following ways:Physical connectivity The CPU must be in the right kind of package to fit into the motherboard.Speed The motherboard’s chipset dictates its external data-bus speed; the CPU must be capableofoperating at that external speed.Instruction set The motherboard’s chipset contains an instruction set for communicatingwith the CPU; theCPU must understand the commands in that set. For example, a motherboarddesigned for an AMD AthlonCPU can’t accept an Intel Pentium CPU, because theinstruction set is different.Voltage The CPU requires that a certain voltage of power be supplied to it via the motherboard’sinterface.This can be anywhere from +5V for a very old CPU down to around +2.1Vfor a modern one. The wrongvoltage can ruin the CPU.There are several ways of differentiating one CPU from another. The following sectionsexplainspecifications according to type, speed, voltage, and cache memory.CPU Speed The Technical Zone
  22. 22. 22 | P a g eThe CPU’s speed is the frequency at which it executes instructions. This frequency is measuredin millions ofcycles per second, or megahertz (MHz); or billions of cycles per second, or gigahertz(GHz).The CPU has aninternal and an external speed. The external speed corresponds with themotherboard’s speed, based on itssystem crystal. The system crystal pulses, generating acadence at which operations occur on themotherboard. Each pulse is called a clock tick. TheCPU’s internal speed is usually a multiple of that, so that multiple operations occur internallyper clock tick.A CPU’s speed as described in its specifications is its internal speed.CPU CacheEach CPU has at least two caches: L1 and L2. The L1 cache is built into the CPU on modernsystems. It’s thefront-side cache, where data waits to enter the CPU. The L2 cache, or backsidecache, is where data exitingthe CPU waits. On modern systems, the L2 cache is withinthe CPU’s packaging but not integrated into theCPU’s die. On older systems, the L2 cache wason a separate set of chips on the motherboard. You cancompare one CPU to another accordingto the size of its L1 and L2 caches.On some CPUs, the L2 cache operates at the same speed as the CPU; onothers, the cachespeed is only half the CPU speed. Chips with full-speed L2 caches have betterperformance.Some newer systems also have an L3 cache, which is external to the CPU. It sits betweentheCPU and RAM to optimize data transfer between them.CPU VoltageA CPU’s voltage is the amount of electricity provided to it by the motherboard. Older CPUs havehighervoltages (around +5V); newer ones have lower voltages (less than +2V in some cases).One reason a givenmotherboard can’t support many different CPUs is that it must providethe correct voltage. To get aroundthis issue, some motherboards have voltage regulator modules(VRMs) that are able to change the voltagebased on the CPU.CPU ManufacturersThe market leader in the manufacture of chips is Intel Corporation, with Advanced MicroDevices (AMD)gaining market share in the home PC market. Other competitors includeMotorola and IBM. The Technical Zone
  23. 23. 23 | P a g eIntroduction to memory and storage devices.MemoryTo pass the A+ exam and be a productive computer technician, youmust be familiar withmemory. Not only will you be tested on thissubject, but one of the most common upgradesperformed on a PCis adding memory. Adding memory is a simple task, but before youcan addmemory you must have the correct type. When we saymemory, we are most often referring to Random Access Memory(RAM). However, there are other types of memory. We’lldiscussthem all in this section. Be familiar with the various typesand their usage.Physical MemoryPhysically, memory is a collection of integrated circuits that store data and program informationas patternsof 1s and 0s (on and off states) in the chip. Most memory chips require constantpower (also called aconstant refresh) to maintain those patterns of 1s and 0s. If poweris lost, all those tiny switches revert backto the off position, effectively erasing the data frommemory. Some memory types, however, don’t requirea refresh.There are many types of RAM. In this section, we examine each type in detail.SRAMStatic RAM (SRAM) stores whatever is placed in it until it’s changed. Unlike dynamic RAM(DRAM), itdoesn’t require constant electrical refreshing. Another name for it is nonvolatileRAM (NVRAM). It’sexpensive, so it isn’t typically used for the main memory in a system.DRAM The Technical Zone
  24. 24. 24 | P a g eDRAM is an improvement over SRAM. DRAM uses a different approach to storing the 1s and0s. Instead ofusing transistors, DRAM stores information as charges in very small capacitors.If a charge exists in acapacitor, it’s interpreted as a 1. The absence of a charge is interpretedas a 0.Because DRAM usescapacitors instead of switches, it needs to use a constant refresh signalto keep the information in memory.DRAM requires more power than SRAM for refresh signalsand, therefore, is mostly found in desktopcomputers.DRAM technology allows several memory units, called cells, to be packed to a highdensity.Therefore, these chips can hold very large amounts of information. Most PCs today useDRAM of one type or another.Let’s take a brief look at some of the different types of DRAM:Fast page mode (FPM) An older type of RAM (almost always 72-pin SIMM packaging) thatisn’tsynchronized in speed with the motherboard. It’s rated in nanoseconds of delay, withlower numbers beingbetter (for example, 60ns). FPM is now obsolete.Extended data out (EDO) Like FPM, an older type of RAM, usually in 72-pin SIMM form.It performs a bitbetter than normal FPM RAM because it needs to be refreshed less frequently.Like FPM, it’s now obsolete.Synchronous DRAM (SDRAM)Synchronized to the speed of the motherboard’s systembus. Synchronizingthe speed of the systems prevents the address bus from having to wait forthe memory because of differentclock speeds. SDRAM typically comes in the form of 168-pinDIMMs or 184-pin RIMMs.Double data rate (DDR) SDRAM/DDR2 Essentially, clock-doubled SDRAM. The memorychip can performreads and writes on both sides of any clock cycle (the up, or start, and thedown, or ending), thus doublingthe effective memory executions per second. So, if you’reusing DDR SDRAM with a 100MHz memory bus,the memory will execute reads and writesat 200MHz and transfer the data to the processor at 100MHz.The advantage of DDR overregular SDRAM is increased throughput and thus increased overall systemspeed. The next generation of DDR SDRAM is DDR2 (double data rate 2). This allows for twoaccesses perclock cycle and effectively doubles the speed of the memory. The Technical Zone
  25. 25. 25 | P a g eVarious memory module form factorsRAMBUSA relatively new and extremely fast (up to 800MHz) technology that uses, for themost part, a newmethodology in memory system design. RAMBUS (also known as directRambus) is a memory bus thattransfers data at 800MHz. RAMBUS memory models (oftencalled Rambus inline memory modules[RIMMs]), like DDR SDRAM, can transfer data onboth the rising and falling edges of a clock cycle. Thatfeature, combined with the 16-bit busfor efficient transfer of data, results in the ultra-high memorytransfer rate (800MHz) and thehigh bandwidth of up to 1.6GBps.Memory Chip Package TypesMemory chips come in many different types of packages. The ones most frequently encounteredarediscussed in the following sections.DUAL INLINE PACKAGE (DIP)Dual inline package (DIP) memory is so named because the individual RAM chips use the DIPstylepackagefor the memory module. Older computers, such as the IBM AT, arranged thesesmall chips like rows ofcaskets in a small memory “graveyard.” This type of memory has longbeen obsolete.SIMMSSingle inline memory modules (SIMMs) were developed because DIPs took up too much realestate on thelogic board. Someone got the idea to put several DIP chips on a small circuitboard and then make thatboard easily removable. The Technical Zone
  26. 26. 26 | P a g eEach of these RAM circuit boards is a stick of RAM. There are two sizes of SIMMs: 30-pinand 72-pin. The30-pin are older, 8-bit sticks. The 72-pin are 32-bit sticks. Figure 1.10 showsone of each. SIMMs are calledsingle because they’re single-sided. When you count the numberof pins (the metal tabs) along the bottom,there are 30 or 72 of them. In contrast, DIMMs(dual inline memory modules) are double-sided; forexample, a 168-pin DIMM has 84 pins oneach side. DIMMSAND RIMMSDIMMs are double-sided memory chips used in modern systems (Pentium and higher).Theytypically have 168 pins and are 64 bits in width. Figure 1.11 shows a DIMM.A RIMM is just like aDIMM, except it’s a Rambus DRAM stick, has 184 pins, and isslightly longer in size.SODIMMS AND MICRODIMMSPortable computers (notebooks and subnotebooks) require smaller sticks of RAM because of their smallersize. Two types are small outline DIMM (SoDIMM) and MicroDIMM.RAM Banks and Bit WidthAs explained earlier, 30-pin SIMMs are 8-bit, 72-pin SIMMs are 32-bit, and DIMMs are 64-bit. Themotherboard has an address bus that carries data from the RAM to the CPU andchipset. It has a certainwidth. On Pentium and higher systems, it’s 64-bit; on earlier systems,it’s 32-bit (386 and 486) or less (286and below). A bank of RAM is a single stick or a groupof sticks where the collective bit width adds up to thewidth of the address bus. For example, on a Pentium motherboard, a single bank consists of a single 64-bitDIMMor a pair of two 32-bit SIMMs. For a 486 motherboard, a single bank is a single 32-bit SIMMor four 8-bit SIMMs.Video RAMVideo memory (also called video RAM [VRAM]) is used to store image data for processing bythe videoadapter. The more video memory an adapter has, the better the quality of image thatit can display. Also,more VRAM allows the adapter to display a higher resolution of image. The Technical Zone
  27. 27. 27 | P a g eIntroduction tostorage devices:Storage DevicesStorage media hold the data being accessed, aswell as the files the system needs to operateanddata that needs to be saved. The various typesof storage differ in terms of capacity, accesstime,and the physical type of media being used.Hard-Disk SystemsHard disks reside inside the computer (usually) and can hold moreinformation than otherforms of storage. The hard-disk system containsthree critical components: the controller, thehard disk, and the hostadapter. The controller controls the drive, the hard disk providesaphysical medium to store the data, and the host adapter is thetranslator.Floppy Drives: A floppy disk drive (referred to by CompTIA as FDD) is a magnetic storage medium thatusesa floppy disk made of thin plastic enclosed in a protective casing. The floppy disk itself (orfloppy, as it’soften called) enables the information to be transported from one computer toanother easily. Thedownside of a floppy disk drive is its limited storage capacity. Floppy disksare limited to a maximumcapacity of 2.88MB, but the most common type of floppy in usetoday holds only 1.44MB. Table 1.1 lists thevarious floppy disks and their capacity. All ofthese except the 1.44MB-capacity model are obsolete, and itisn’t far behind.CD-ROM Drives: CD-ROM stands for Compact Disc Read-Only Memory. TheCD-ROM is used for long-termstorage of data. CD-ROMs are read-only,meaning that once information is written to a CD,it can’t be erased orchanged. Access time for CD-ROMs is considerably slower than for aharddrive. CDs normally hold 650MB of data and use the ISO 9660 standard, which allows themto be usedin multiple platforms. The Technical Zone
  28. 28. 28 | P a g eZip Drives and Jazz DrivesIomega’s Zip and Jaz drives are detachable, external hard disks that areused to store a large volume (around 100MB for the Zip, 1GB and 2GBfor the Jaz) of data on a single, floppy-sized disk. The drives connect toeither a parallel port or a special interface card. The major use of Zip andJaz drives is to transport large amounts of data from place to place. Thisused to be accomplished with several floppies.Tape Backup DevicesAnother form of storage device is the tape backup. Tape backup devices can beinstalled internally or externally and use a magnetic tape medium instead of disksfor storage. They hold much more data than any other medium but are also muchslower. They’re primarily used for archival storage.Optical DrivesOptical drives work by using a laser rather than magnetism to change the characteristics of the storagemedium.Flash Drives (and SD Cards)Flash drives have been growing in popularity for years and replacingfloppy disks due to their capacity and small size. Flash is ideally suited foruse not only with computers, but also withmany other things—digitalcameras, MP3 players, and so on.Thumb DrivesThumb drives are USB flash drives that have become extremely popular for transporting files.External Hard DrivesA number of vendors are now making external hard drives. These often connect tothe computerthrough the USB port, but can also connect through the network (andbe shared by otherusers) or other connections. While some are intended forexpansion, many are marketed forthe purpose of “mirroring” data on the internaldrive(s) and often incorporate a push-buttonswitch that starts a backup. The Technical Zone
  29. 29. 29 | P a g eIntroduction to ports, slots, connectors andpower supplyPeripheral Ports and ConnectorsIn order for a computer to be useful and have the mostfunctionality, there must be a way to get the data into and out of it. Many different ports are available forthis purpose. We will discuss the different types of ports and how they work later in this chapter. Briefly,the seven most common types of ports you will see on a computer are serial, parallel, Universal Serial Bus(USB), video, Ethernet, sound in/out, and game ports.AT System ConnectorsThe next type of power connector is called the AT system connector. There are two 6-wire connectors,labeled P8 and P9 (as shown in Figure 1.39). They connect to an AT-style motherboard and deliver thepower that feeds the electronic components on it. These connectors have small tabs on them thatinterlock with tabs on the motherboard’s receptacle. If there are two connectors, you must install them inthe correct fashion. To do this (on most systems), place the connectors side by side with their black wirestogether, and then push the connectors onto the receptacle on the motherboard.Floppy drive power connectorAT power supply system board connectorsA standard peripheral power connector ATX power connector The Technical Zone
  30. 30. 30 | P a g eATX12V P4 power connectorSATA power connectorOther Types of PortsA few other ports are used with computers today. These ports include the following:_ Universal Serial Bus (USB)_ IEEE 1394 (FireWire)_ Infrared_ Audio jacks_ PS/2 (mini-DIN)_ CentronicsUniversal Serial Bus (USB)Most computers built after 1997 have one or more flat ports in place of one DE9M serialport. These ports are Universal Serial Bus (USB) ports, and they are used for connectingmultiple (up to 127) peripherals to one computer through a single port (and the use ofmultiport peripheral hubs). USB version 1.1 supported data rates as high as 12Mbps(1.5MBps). The newest version, USB 2.0, supports data rates as high as 480Mbps (60MBps).PS/2 (Keyboard and Mouse)Another common port, as mentioned earlier, is the PS/2 port. A PS/2 port (also known as amini-DIN 6 connector) is a mouse and keyboard interface port first found on the IBM PS/2(hence the name). It is smaller than previous interfaces (the DIN-5 keyboard port and serialmouse connector), and thus its popularity increased quickly.and mouse, respectively, imprinted next to the ports. The Technical Zone
  31. 31. 31 | P a g eCentronicsThe last type of port connector is the Centronics connector, a microribbon connector named for the Wang subsidiary that created it. Ithas a unique shape. It consists of a central connection barsurrounding by an outer shielding ring. The Centronics connectorwas primarily used in parallel printer connections and SCSIinterfaces. It is most often found onperipherals, not on computers themselves (except in the case ofsome older SCSI interface cards).Power SuppliesThe device in the computer that provides the power is thepower supply. A power supply converts 110-volt AC current intothe voltages a computer needs to operate. On an ATmotherboard,these are +5 volts DC, –5 volts DC, +12 volts DC,and –12 volts DC. Components inmodern PCs don’t use thenegative voltages; they’re provided for backwardcompatibilityonly. On an ATX motherboard, an additionalvoltage is provided: +3.3 volts DC.Power-supply problems areusually easy to troubleshoot. The system doesn’t respond inany way when the power is turned on. Whenthis happens, open the case, remove the powersupply, and replace it with a new one.Be aware thatdifferent cases have different types of on/off switches. The process of replacinga power supply is a loteasier if you purchase a replacement with the same mechanism.Even so, remember to document exactlyhow the power supply was connected to the on/offswitch before you remove it.Power supplies containtransformers and capacitors that carry lethal amounts of current.They aren’t meant to be serviced. Do not attempt to open them or do any work on them. shows a genericpower supply.A power supply has a rated output capacity in watts, and when you fill a system withpower-hungry devices,you must make sure that maximum capacity isn’t exceeded. Otherwise,problems with power can occur,creating lockups or spontaneous reboots.To determine the wattage a device draws, multiply voltage bycurrent. For example, if adevice uses 5 amps of +3.3V and 0.7 amps of +12V, a total of 25 watts isconsumed. Do thiscalculation for every device installed. Most devices have labels that state their powerrequirements.Some devices don’t have power labels The Technical Zone
  32. 32. 32 | P a g eEstimating Power ConsumptionMotherboard 20–30 wattsCPU 30–70 watts (faster CPU, more watts)AGP video card 20–50 wattsPCI circuit boards 5 watts eachISA circuit boards 10 watts eachFloppy drive 5 wattsCD drive 10–25 wattsRAM 8 watts per 128MBIDE hard drive 5–15 wattsSCSI hard drive 10–40 wattsPrinciples of Laptops and Portable Devices:Whether you choose to call them laptops, portable devices, or something different is mostly a matter ofsemantics. This objective tests your knowledge of some of the basic operations of laptops. In many cases,the components are the same as in a desktop computer, and they were discussed in Chapter 1. Those thatare different are focused on here.Critical InformationA portable computer must provide all the functionality of a desktopcounterpart yet be able to withstand travel, run in the absence of ACpower, and be much smaller and more compact. When you get rightdown to it, there is not a great deal of difference between laptop anddesktop computers, with the exception that laptops are more difficultto disassemble and form factors on items such as motherboards,memory, and hard drives become important. While they perform the The Technical Zone
  33. 33. 33 | P a g esame functions, size is critical. Laptop-specific elements are discussed in the following sections.Laptops vs. DesktopsIf you’ve ever shopped for a laptop, you have no doubt noticed that the prices of desktop PCs are oftenquite a bit lower than for notebook computers, yet they are faster and more powerful. If you’ve everwondered what makes a laptop so much different than a PC, here are the primary differences betweenlaptops and desktops:PortabilityThis is probably the most obvious difference. Laptops are designed to be portable. They run on batteries,so you aren’t tied to one spot at home or at the office. Networking options are available that allow you toconnect to a network wirelessly and do work from just about anywhere, including malls, airports,Starbucks, and so on. As anyone who’s tried tobring their full-tower PC to a LAN party can tell you, desktops just aren’t that portable.CostLaptops cost more—sometimes as much as 60 to 80 percent more—thandesktop computerswith similar features. The primary reason is thatportability requires small componentsand unique proprietary designs forthose components so they fit into the small size necessary.Miniatureversions of components cost more money than standard-size (desktop)versions.PerformanceBy and large, laptops are always going to lose out somewhere in theperformance department. Compromises must often be madebetween performance and portability, and considering that portabilityis the major feature of a laptop, performance is what usually suffers.While it is possible to have a laptop with comparable performance to a desktop, the amount of money onewould have to spend for a “desktop replacement” laptop is considerable. This is not to say that a laptopcan’t outperform a desktop, it’s just that the “bang for the buck” factor is higher in a desktop.A laptop motherboard The Technical Zone
  34. 34. 34 | P a g eA desktop hard drive compared to a laptop hard drive144-pin SoDIMMUnderstanding Operating SystemsComputers are pretty much useless without software. A piece of hardware makes a good paperweight ordoorstop, unless you have an easy way to interface with it. Software is that interface. While there aremany types of software, or programs, the most important application you’ll ever deal with is the operatingsystem. Operating systems have many different, complex functions, but two of them jump out as beingcritical: one, interfacing with the hardware, and two, providing a platform on which other applications canrun. Here are three major distinctions of software to be aware of: The Technical Zone
  35. 35. 35 | P a g eIntroduction to Operating System.Operating System (OS)Provides a consistent environment for other software to execute commands.The OS gives users an interface with the computer so they can send commands (input) and receivefeedback or results (output). To do this, the OS must communicate with the computer hardware toperform the following tasks:Disk and file managementDevice accessMemory managementOutput formatWhat’s in a Window?We have now looked at the nature of the Desktop, the Taskbar, the Start menu, and icons. Each of theseitems was created for the primary purpose of making access to user applications easier, and theseapplications are in turn used and managed through the use of windows, the rectangular applicationenvironments for which the Windows family of operating systems is named. We will now examine howwindows work and what they are made of. A program window is a rectangular area created on the screenwhen an application is opened within Windows. This window can have a number of different forms, butmost windows include at least a few basic elements. The Technical Zone
  36. 36. 36 | P a g eWindows VersionsWindows 1Version 1 of Windows featured the tiling windows, mouse support, and menu systems that still drive next-generation OSs such as Windows 98, Windows CE, and Windows 2000Windows 2Version 2, released in 1987, added icons and allowed application windows to overlap each other, as well astile. Support was also added for PIFs (program information files), which allowed the user to configureWindows to run their DOS applications more efficientlyWindows 3.xWindows 3.0 featured a far more flexible memory model, allowing it to access more memory than the640KB limit normally imposed by DOS. It also featured the addition of the File Manager and ProgramManager, allowed for network support, and could operate in 386 EnhancedmodeWindows 95Although it dominated the market with its DOS operating system and its add-on Windows interface,Microsoft found that the constraints of DOS were rapidly making it difficult to take full advantage of rapidlyimproving hardware and software developmentsWindows 98/Me/NT/2000/XPAfter Windows 95, Windows 98 was introduced as its successor, followed by Windows Me (MillenniumEdition). Windows 98/Me is still a very common PC OS to find on users’ computers, but XP is even morecommon yet. The Technical Zone
  37. 37. 37 | P a g eWindows Vista& window 7: Scheduled to launch in early 2007, Windows Vista (formerly code-namedLonghorn) is the newest operating system platform developed by Microsoft. It will be presented in fivedifferent versions: Business, Enterprise, Home Premium, Home Basic, and Ultimate.The Command Prompt: Although we’re talking about the Windows operating system in this book, itsancestor, the Microsoft Disk Operating System (MS-DOS), still plays a role in Windows today. MS-DOS wasnever meant to be extremely friendly. Its roots are in CP/M, which, in turn, has its roots in Unix. Both ofthese older OSs are command line–based, and so is MS-DOS. In other words, they all use long strings ofcommands typed in at the computer keyboard to perform operations. Some people prefer this type ofinteraction with the computer, including many folks with technical backgrounds (such as yours truly).Although Windows has left the full command-line interface behind, it still contains a bit of DOS, and youget to it through the command prompt.The Registry: Windows configuration information is stored in a special configuration database known asthe Registry. This centralized database contains environmental settings for various Windows programs. Italso contains registration information that details which types of file extensions are associated with whichapplications. So, when you double-click a file in Windows Explorer,the associated application runs andopens the file you double-clicked. The Registry is broken down into a series of separate areas called hives.These keys are divided into two basic sections—user settings and computer settings. In Windows 2000 andXP, a number of files are created corresponding to each of the different hives. Most of thesefiles do not have extensions, and their names are system, software, security, sam, and default. Oneadditional file that does have an extension is NTUSER.DAT.The basic hives of the Registry are these:HKEY_CLASSES_ROOT: Includes information about which file extensions map to particular applications.HKEY_CURRENT_USER: Holds all configuration information specific to a particular user, such as theirDesktop settings and history information.HKEY_LOCAL_MACHINE: Includes nearly all configuration information concerning the actual computerhardware and software.HKEY_USERS: Includes information about all users who have logged on to the system. TheHKEY_CURRENT_USER hive is actually a subkey of this hive.HKEY_CURRENT_CONFIG: Provides quick access to a number of commonly needed keys that are otherwiseburied deep in the HKEY_LOCAL_MACHINE structure.Virtual Memory The Technical Zone
  38. 38. 38 | P a g eAnother thing you may need to configure is virtual memory. Virtual memory uses what’s called a swap file,or paging file. A swap file is actually hard-drive space into which idle pieces of programs are placed, whileother active parts of programs are kept in or swapped into main memory. The programs running inWindows believe that their information is still in RAM, but Windows has moved the data into near-linestorage on the hard drive. When the application needs the information again, it is swapped back into RAMso that it can be used by the processor.Windows System Files: Among the things you must be familiar with in preparation for the A+ exam are thestartup and system files used by Windows 2000 and Windows XP. We will look at each of them individually,but Windows makes nosing around in the startup environment difficult, and so there is a change you needto make first.Key Boot Files: Windows 2000 and XP require only a few files, each of which performs specific tasks:NTLDR Bootstraps the system. In other words, this file starts the loading of an OS on thecomputer.BOOT.INI Holds information about which OSs are installed on the computer.BOOTSECT.DOS: In a dual-boot configuration, keeps a copy of the DOS or Windows 9x boot sector so thatthe Windows 9x environment can be restored and loaded as needed.NTDETECT.COM:Parses the system for hardware information each time Windows 2000/XP is loaded. Thisinformation is then used to create dynamic hardware information in the Registry.NTBOOTDD.SYS:On a system with a SCSI boot device, used to recognize and load the SCSI interface. OnEIDE systems, this file is not needed and is not even installed.NTOSKRNL.EXE The Windows 2000/XP OS kernel:System Files In addition to the previously listed files, allof which except NTOSKRNL.EXE are located in the root of the C: partition on the computer, Windows2000/XP needs a number of files from its system directories (e.g., system and system32), such as thehardware abstraction layer (HAL.DLL). Numerous other DLL (dynamic link library) files are also required,but usually the lack or corruption of one of them produces a noncritical error, whereas the absence ofHAL.DLLcauses the system to be nonfunctional.System Files Configuration Tools in Windows 2000/XP The Technical Zone
  39. 39. 39 | P a g eThe MSCONFIG system-configuration tool that was available in Windows 9x doesn’t exist in Windows 2000.It is, however, included with Windows XP.Disk ManagementWhere there are files, there are disks. That is to say, all the files and programs we’ve talked about so farreside on disks. Disks are physical storage devices, and these disks also need to be managed. There areseveral aspects to disk management. One is concerned with getting disks ready to be able to store files andprograms. Another deals with backing up your data. Yet another involves checking the health of disks andoptimizing their performance. We’ll look at these aspects in more detail.Backing Up the Data on Your DrivesAnother very important aspect of disk management is backing up the data on your drives. Sooner or later,you can count on running into a situation where a hard drive fails or data becomes corrupted. Without abackup copy of your data, you’re facing a world of trouble trying to re-create the data, if that’s evenpossible or economically feasible. You also shouldn’t rely on the Recycle Bin. Although it is a good utility torestore an occasional file or directory that a user has accidentally deleted, it will not help you if your drivesand the data on them become unusable.File Managementfile management is the process by which a computer stores data and retrieves it from storage. Althoughsome of the file-management interfaces across Windows interfaces may have a different look and feel, theprocess of managing files is similar across the board.Files and FoldersFor a program to run, it must be able to read information off the disk and write information backto thedisk. In order to be able to organize and access information—especially in larger new systems that mayhave thousands of files—it is necessary to have a structure and an ordering process. The Technical Zone
  40. 40. 40 | P a g eIntroduction to basic troubleshooting ofcomputer Hardware & Software.Basic Aspects of TroubleshootingAlthough everyone approaches troubleshooting from a different perspective, a few things should remainconstant. Among them is a basic appreciation for data. Any hardware component can be replaced, but dataoften can’t be. For that reason, it’s important to always perform backups before making any changes.Basic Diagnostic ProceduresStep 1: Define the ProblemIf you can’t define the problem, you can’t begin to solve it. You can define the problem by asking questionsof the user. Here are a few questions to ask the user to aid in determining what the problem is, exactly:Step 2: Check the Simple Stuff FirstThis step is the one that most experienced technicians overlook. Often, computer problems are the resultof something simple. Technicians overlook these problems because they’re so simple that the techniciansassume they couldn’t be the problem.Step 3: Check to See If It’s User ErrorThis error is common but preventable. The indication that a problem is due to user error is when a usersays he can’t perform some very common computer task, such as printing or saving a file. As soon you hearthese words, you should begin asking questions to determine if it’s simply a matter of teaching the user thecorrect procedure. A good question to ask following his statement of the problem is, “Were you ever ableto perform that task?” If he answers no to this question, it means he’s probably doing the procedurewrong. If he answers yes, you must move on to another set of questions.Step 4: Restart the ComputerIt’s amazing how often a simple computer restart can solve a problem. Restarting the computer clears thememory and starts the computer with a clean slate. The Technical Zone
  41. 41. 41 | P a g eStep 5: Determine If the Problem Is Hardware or Software RelatedThis step is important because it determines on what part of the computer you should focus yourtroubleshooting skills. Each part requires different skills and different tools.Step 6: If the Problem Is Hardware Related, Determine Which Component Is FailingHardware problems are pretty easy to figure out. If the modem doesn’t work, and you know it isn’t asoftware problem, the modem is probably the piece of hardware that needs to be replaced.Step 7: Check Service Information SourcesAs you may (or may not) have figured out by now, we’re fond of old sayings. Another old sayingapplieshere: “If all else fails, read the instructions.” The service manuals are your instructions for troubleshootingand service information.Step 8: If It Ain’t Broke …When doctors take the Hippocratic oath, they promise to not make their patients any sicker than theyalready were. Technicians should take a similar oath. It all boils down to “If it ain’t broke, don’t fix it.Step 9: Ask for HelpIf you don’t know the answer, ask one of your fellow technicians. They may have run across the problemyou’re having and know the solution.POST RoutinesEvery computer has a diagnostic program built into its BIOS called the power-on self-test(POST). When youturn on the computer, it executes this set of diagnostics. Many steps areinvolved the POST, but theyhappen very quickly, they’re invisible to the user, and they varyamong BIOS versions. The steps include checking the CPU, checking the RAM, checking for the presence ofa video card, and so on. The main reason to be aware of the POST’s existence is that if it encounters aproblem, the boot process stops. Being able to determine at what point the problem occurred can help youtroubleshoot. The Technical Zone
  42. 42. 42 | P a g e Applying Basic Troubleshooting Techniques Identifying Motherboard and CPU Problems Identifying I/O Ports and Cables Identifying Cooling Issues Identifying Case Issues Identifying Hard-Disk System Problems Identifying Display Device Problems Identifying Floppy and Other Removable Disk-Drive Problems Identifying Sound Card Problems Identifying CD-ROM/DVD Issues Identifying NIC Issues The Technical Zone

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