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1. lol I a IEEE Eo B M N H K L 6 From the figure depicting an ATX motherboard shown in question 5 identify the AGP expansion slot O AA O B B 1 O 7 From the figure depicting ATX motherboard shown question 5 identify the IDE connectors O B J O CK O D M 111 Exam Prep Questions 8 From the figure depicting an ATX motherboard shown in question 5 identify the battery O So gt r o 9 From the figure depicting an ATX motherboard shown in question 5 identify the DIMM slots O O C H O D N 10 Locate the serial port connector in the diagram of an ATX back panel O c D D BACK OF UNIT aED oja 112 Chapter 2 PC System Boards 11 From the figure depicting an ATX back panel shown in question 10 locate the printer 12 13 14 15 port O gt gt gt What should you do first if the system clock fails to keep proper time after being reset by the operating system O O O O A Reload the operating system B Replace the battery D Replace the motherboard Clean the battery contacts What may happen when you change the translation mode setting for an existing IDE drive O O O O So gt Loss of all data on the
2. PCI CONNECTORS le CONNECTORS PClet6X CONNECTOR ps2 MOUSE PORT SOUND AUDIO POWER SOUTH CATS OUTPUTS CONNECTOR BRIDGE PORT FIGURE 2 2 BTX system board The microprocessor has been moved toward the front center section of the board as have the chipset devices The major source of cooling in the BTX sys tem is the thermal module depicted in Figure 2 3 The thermal module mounts to the front of the system unit and sits directly over the microprocessor and chipset components to provide inline airflow across the components This reduces the need for additional cooling fans and heat sinks which in turn low ers the cost of the unit BTX thermal modules come in two varieties a standard height Type I version which is designed for full height cases and a low profile Type II version designed for small form factor cases This configuration also improves the acoustics of the unit which is becoming an area of greater concern as PCs are increasingly being used as media servers Media servers are specialized PCs designed specifically for delivering audio and 63 System Board Form Factors video services in the home setting In these applications the sound levels gener ated by cooling and case fans can reach unacceptable levels DUCT 3 QIIIA nu MODULE HEATSINK _ EXHAUST COOL AIR FIGURE 2 3 BTX thermal modules draw cool air in from the top pulling it over the top of the processor a
3. There are currently three common disk drive connection interfaces provided on system boards Parallel Advanced Technology Attachment PATA and Serial AT Attachment SATA connectors for IDE drives and possibly a FDC interface connection 86 Chapter 2 PC System Boards PATA and SATA interfaces are designed to serve a particular type of drive that places the bulk of the drive controller circuitry on the disk unit instead of on an adapter card These drives are referred to as IDE drives The IDE designation was originally used to refer to all ATA devices until the advent of the serial ATA interface At this point discussions of IDE drives and their interfaces had to be segmented into terms of parallel and serial ATA drives Figure 2 20 provides an example of a system board that supplies the system s PATA and SATA host adapter connections along with the FDC interface connection FDD SIGNAL PIN 1 FIGURE 2 20 System board disk drive connections The FDC portion of the chipset can control two floppy disk drives whose sig nal cable connects to the system board at the 34 pin BERG connector labeled FD1 As with any disk drive connections caution must be taken when connect ing the floppy disk drive signal cable to the system board pin 1 of the connec tor must line up with the signal cable s indicator stripe PATA Connections The parallel IDE host adapter portion of the chipset furnishes two complete IDE channels IDE1 and I
4. for this function Finally LPX units typically had poor ventilation characteris tics the low case height and horizontally mounted adapter cards tended to trap heat near the system board surface The new low profile extended NLX form factor depicted in Figure 2 7 did become a legitimate standard for cases power supplies and system boards However manufacturers have chosen to produce low profile units based on microATX and miniATX designs These form factors followed the ATX design specification but reduced the size of the unit and its associated costs by limit ing the number of expansion slots BACK PLANE CARD SYSTEM BOARD POWER BACK PLANE CARD Au SUPPLY XPANSION EXPANSION E Naor LO SETS OPENINGS 5 PROCESSOR DRIVE SYSTEM MEMORY NLX SYSTEM 2 HARD DISK UNIT CASE DRIVE so SYSTEM We PROCESSOR FAN FIGURE 2 7 NLX components Pentium Chipsets Integrated circuit manufacturers develop different chipsets to support different processor types The typical Pentium chipset consists of a memory controller called the North Bridge a PCI host bridge referred to as the South Bridge and 67 System Board Form Factors in some older versions a Super or enhanced I O controller The memory con troller provides the interface between the system s microprocessor its various memory sections and the PCI bus In turn the host bridge monitors the microprocessor s address bus to determin
5. CMOS setup utility of a particular BIOS may contain these same options or options that perform the same functions under a different name or it may not contain some of these options at all 97 CMOS RAM ROM PCI ISA BIOS 2A5KFR3B CMOS SETUP UTILITY AWARD SOFTWARE INC STANDARD CMOS SETUP INTEGRATED PERIPHERALS BIOS FEATURES SETUP SUPERVISOR PASSWORD CHIPSET FEATURES SETUP USER PASSWORD POWER MANAGEMENT SETUP IDE HDD AUTO DETECTION PNP PCI CONFIGURATION HDD LOW LEVEL FORMAT LOAD BIOS DEFAULTS SAVE amp EXIT SETUP LOAD SETUP DEFAULTS EXIT WITHOUT SAVING Esc Quit Ay gt lt Select Item F10 Save amp Exit Setup Shift F2 Change Color Virus Protection Boot Sequence FIGURE 2 25 The CMOS Main Menu screen BIOS designers have built two options Auto Configuration and Default Settings into newer versions to help users deal with the complexity of the advanced CMOS configuration Newer system boards use an auto configuration mode that takes over most of the setup decisions Working well in most cases this option produces settings for an efficient basic level of operation for stan dard devices in the system However it doesn t optimize the performance of the system Io do that it s necessary to turn off the autoconfiguration feature and insert the desired parameters into the configuration table Two options typical ly exist for the autoconfiguration function Auto Configure with Power On Defaults and Auto Configu
6. EIDE interface is often described as an ATAPI AT Attachment Packet Interface or a Fast ATA Fast AT Attachment interface The original PATA IDE interface employed 40 wire cables between the system board interfaces and the drive units Of these 40 wires only 7 were ground wires As transfer speeds across the PATA cabling increased the large separation between each signal line and its respective return ground line resulted in decreased reliability over this cable For transfer rates greater than 33MHz the original 40 wire cable was replaced by an 80 wire version that alternates ground and signal lines This arrangement reduces interference between signal lines which greatly increased the reliabili ty of each line at higher frequencies These cables have a maximum length spec ification of 18 inches The 80 wire cables still use the 40 pin IDE connector at each end to remain compatible with standard PATA connections These cables are typically color coded to prevent them from being confused with older 40 wire cables which are typically gray However when newer EIDE devices are connected to the system using an older 40 conductor cable they will default to operating speeds compat ible with the older IDE standards Many PATA cable manufacturers also color code the connectors on their cables to suggest where each connector should be attached in the system The blue connector is intended to be connected to the system board s PATA interface
7. Item Help Smart CPU Fan Temperature Disabled gt In m FAN Spee RPM U FAN Speed RPM t Power FAN Speed RPM 1 53 V 1 50 V yset Voltage 1 60 U 4 9 U 3 tage itage IMM Voltage 72 0 attery Voltage 20 5U Standby 5 05 V ACPI Shutdown Temperature 75 C 167 F fi Move Enter Select PU PD Value Fi0 Save ESC Exit Fi General Help F5 Previous Values F6 Fail Safe Defaults Optimized Defaults FIGURE 2 27 The PC Health Menu screen Finally this screen enables you to establish warning and system shut down lev els that will either warn the user that something is going wrong or will go ahead and shut the system down to protect the microprocessor from harm Security Subsystem Most BIOSs offer a variety of security options that can be set through the CMOS setup utility Figure 2 28 displays a typical Security Configuration screen Typically these options include setting User passwords to control access to the system and Supervisory passwords to control access to the CMOS setup utility The User password option enables administrators to establish passwords that users must enter during the startup process to complete the boot process and gain access to the operating system However this password does not pro vide access to the CMOS setup utility The Supervisory password option estab lishes a password that must be used to access the CMOS setup utility where the User and Supervisory password options are
8. access to the system without completely resetting the content of the CMOS RAM On some system boards this can be accomplished by shorting a special pair of jumpers on the board With other systems you will need to remove or short across the backup battery to reset the CMOS information It will also be necessary to unplug the power from the commercial outlet to reduce the voltage to the CMOS registers When the content of the CMOS is reset you must manually restore any nondefault CMOS settings being used by the system EXAM ALERT Be aware of the effects of forgetting a CMOS password and know what steps must be taken to restore the system in this event 109 Exam Prep Questions Exam Prep Questions 1 What type of expansion bus is based on a 124 pin slot O O O O A B C D ISA PCI AGP PC bus 2 Which IRQ resources are assigned in the PnP configuration process Qoo A Motherboard devices B ISA devices C D Legacy devices PCI devices 3 What type of expansion card is plugged into an AGP slot C D Graphics Modem Network Sound 4 What is the maximum data throughput when connecting an Ultra ATA 66 hard disk drive with a 40 pin IDE cable O O O O A 10Mbps B 33Mbps C D They will not work together 66Mbps 110 Chapter 2 PC System Boards 5 From the figure depicting an ATX motherboard identify the ISA expansion slot
9. area and RTC functions have been integrated with a 10 year nonreplaceable lithium cell in an independent RTC IC module If the power source or the backup battery becomes defective the system s capa bility to keep proper time and date information will be impaired On older sys tem boards the backup battery was completely responsible for maintaining the information in the RTC With newer systems there is a 5Vdc level present on 99 CMOS RAM the system board even when the system is turned off On these boards the power supply and the battery in the RTC module work together to keep the time and date information correct If the time is incorrect on a PC system the easiest way to reset it is through the operating system however if the system continually fails to keep good time you should replace the battery If that doesn t work check for corrosion on the bat tery contacts Clean the contacts with a pencil eraser and retry the battery Next you should try replacing the RTC module If this does not correct the timekeep ing problem the electronic circuitry that recharges the battery may be defective and in this case you need a new motherboard EXAM ALERT Be aware of where to go to reset the system clock and what to check if the clock fails to keep proper time Disk Drive Support Most BIOSs possess autodetect options that automatically detect the type of hard drives installed in the system and load their parameters into the CM
10. combination of x1 x2 or x4 slots 79 Expansion Slots PCle Slots PCle employs four slot connector sizes The x1 slot contains 36 contact posi tions The x4 slot is physically larger and has 64 pins the x8 version uses 98 pins and the x16 has 164 pins Figure 2 15 shows the different PCIe expansion slots and their pin assignments Side B Connector Side A Connector Pin 1X PCle 4X PCle 25 8X PCle 16X PCle Bi s 78 Bat B82 Hal Plug Detect FIGURE 2 15 PCle slots and pinouts for each The number and arrangement of PCIe slots on system boards is largely up to the discretion of the system board manufacturer The BTX form factor specifi cation calls for one x16 slot and two 1 slots for its system boards The x16 slot replaces the traditional AGP slot covered in the next section of this chapter for the graphic display adapter Some system boards include two x16 slots whereas others offer a mixture of x8 x4 and x1 slots These system boards may also include some number of traditional PCI slots It is permissible to plug PCle adapter cards with fewer lanes into a larger slot for instance a x8 card into a x16 slot The card s edge connector will not fill the slot but the electrical contact connections should line up properly and the card should function correctly The PCIe host adapter known as a PCIe switch 80 Chapter 2 PC System Boards portion of the chipset will a
11. configured EXAM ALERT Be aware of the types of passwords that can be established through the CMOS Setup utility 108 Chapter 2 PC System Boards PhoenixBIOS Setup Utility Security Item Specific Help Set User Password Enter Set Supervisor Password X Enter upervisor passwor Virus Check Reminder Disabled controls access to Setup System Backup Reminder Disabled utility Password on boot Disabled Diskette access Disabled Fixed disk boot sector normal F1 Help Select Item Change Values F9 Setup Defaults ESC Exit 4 Select Menu Enter Select gt Sub Menu F10 Save and Exit FIGURE 2 28 The CMOS Security configuration The Security Configuration screen may also include options for setting virus check and backup reminders that pop up periodically when the system is boot ed In addition to enabling these settings administrators can also specify the time interval between notices One of the main sets of security options in the CMOS setup utility consists of those that can be used to control access to the system For the most part these options cover such things as access permitted through the floppy drive and access to the boot sector of the drive Because the CMOS password controls access to all parts of the system even before the bootup process occurs there is some inconvenience in the event that the user forgets a password When this occurs it will be impossible to gain
12. power supply and I O connector placements In particular the ATX specification for the power supply connection calls for a single 20 pin power cord between the sys tem board and the power supply unit This cable provides a 3 3V DC supply along with the traditional 12V DC and 5V DC supplies A software activated power switch can also be implemented through the ATX power connector specification The PS ON and 5VSB 5V Standby signals can be controlled by the operating system to perform automatic system shutdowns 62 Chapter 2 PC System Boards As mentioned in Chapter 1 Basic PC Terms and Concepts newer ATX power supplies include a 4 pin 12V EPS clip on extension to the standard 20 pin ATX power connector The additional conductors provide additional current carrying capabilities to support newer microprocessors and high end peripherals BTX System Boards The BTX form factor specification is designed to provide better thermal han dling capabilities better acoustic characteristics and provisions for newer PC technologies The BTX form factor is not compatible with the older ATX spec ification It moves key components such as the microprocessor chipset and video controller to new general locations on the system board to achieve better airflow and cooling characteristics inside the system unit Figure 2 2 depicts the recommended full size version of a BTX system board CPU FAN HEATSINK NORTH BRIDGE
13. shut down the computer You cannot log in to the computer What action must be taken to restore the system if the CMOS password is forgotten in an ATX system Change the Password Enable setting in CMOS B Remove the battery C D Unplug the computer from the wall and remove the battery Short the CMOS enabling jumper and remove the battery 114 Chapter 2 PC System Boards 21 22 23 24 25 Where is the PnP information stored in the BIOS O The RTC module The ESCD area O The PnP Registry O D The Device Manager The system s time and date configuration can be performed in the A Memory cache B North Bridge C CMOS setup D South Bridge Qo What is the major difference between EPP and ECP operation of the parallel port O DMA mode O Bidirectional O 16 bit transfers O D Serial transfers Which parallel port type has the highest throughput ECP EPP O D SPP What type of communication is possible with an IEEE 1284 parallel cable A Bidirectional half duplex Bidirectional full duplex B C Simplex D Selectable half or full duplex 115 Exam Prep Questions 26 If you place a bootable floppy in drive A and the system boots to drive C what action should you take to correct this 27 28 29 D Reconfigure the drive seek s
14. to 5 5 GBps in each direction Each two pair communication path is referred to as a Jane and is capa ble of transmitting one byte at a time in both directions at once This full duplex communication is possible because each lane is made up of one send and one receive path Under the PCIe specification PCIe switching devices can combine multiple PCIe lanes together to provide additional bandwidth between the PCIe host and the PCIe device Each complete connection between a host and a device or slot 78 Chapter 2 PC System Boards is referred to as a ink Figure 2 14 illustrates the relationship between PCIe lanes and links In this example two PCIe lanes are routed to a particular PCIe slot configuration to provide a two lane x2 link capable of carrying twice as much information as a single lane link x1 X1 LINK X2 LINK FIGURE 2 14 PCIe lanes and links The PCIe specification supports 1 2 x4 x8 x12 x16 and x32 lane links However available PCle chipsets provide for only 20 lanes and 16 are typical ly used for the x16 PCIe graphics slot The PCIe switches depicted in the fig ure are built into the South Bridge of the chipset and provide links to most of the PCIe expansion slots In some chipset versions the x16 slots are connected directly to a PCIe switch in the North Bridge date this slot is the most suc cessful implementation of the PCIe standard The other four lanes can be dis tributed between any
15. 00 1066 DDR2 533 PCle x SATA 3Gbps 667 8GB 16 1 955X Express 800 1066 DDR2 533 PCle x SATA 3Gbps 667 8GB 16 x1 945G Express 533 800 533 800 PCle x SATA 3Gbps 1066 1066 16 x1 4 6 925XE Express 800 1066 DDR2 400 PCle x SATA 533 16 x1 1 5Gbps 925X Express 800 DDR2 400 PCle x SATA 533 16 x1 1 5Gbps 915G Express 533 800 DDR PCle x SATA DDR2 533 16 1 150Mbps Celeron D 910GL Express 533 DDR 333 PCle x SATA 400 1 4 6 150Mbps System Bus Speeds Microprocessor and chipset manufacturers are continually developing products to speed up the operation of the system The first method used to speed up the system is to separate the speed at which the internal core of the processor runs from that of all the buses and devices external to it In the Pentium processor two speed settings can be established for the microprocessor one is the core speed at which the internal microprocessor operations take place and the second is a derivative bus speed for its external bus transfers These two operational speeds are tied together through an internal clock multiplier system The second method is to speed up the movement of data across its data buses As the previous chipset figures in this chapter have shown the buses operating directly with the microprocessor and North Bridge referred to as the Front Side Bus FSB are running at one speed whereas the PCI bus is running at a 73 Expansion Slots different speed and the
16. 1 5V and PCI Express slots The dual inline memory module DIMM slots are located near the micro processor and its chipset components The various BTX system board sizes are intended to allow the same technolo gies to be used in tower desktop and low profile configurations Figure 2 5 illustrates how these variations are implemented in the different case styles The BTX specification makes provisions for using ATX power supplies as well as low profile form factor LFX and compact form factor CFX small form fac tor power supplies The BTX back panel moves the rear panel I O connectors depicted in Figure 2 6 to the center of the back panel This layout is the result of better placement of the I O controller on the system board Most B TX back panels include PS 2 mouse and keyboard connectors VGA Video Graphics Array video connec tions and legacy parallel printer serial ports In addition the BTX back panel may offer a variety of consumer audio and video connection combinations TOWER SIDE VIEW OPTICAL DISK DRIVE SYSTEM BOARD FRONT SIDE PERIPHERALS FIGURE 2 5 BTX implementations e 2 4 i a 65 System Board Form Factors DESKTOP TOP VIEW CARD ON RISER SYSTEM MEMORY OPTICAL DISK DRIVE THERMAL MODULE SYSTEMI SMALL FORM FACTOR TOP VIEW uw POWER SUPPLY UNIT SYSTEM MEMORY PROCESSOR p THERMAL MODULE MOBILE OPTICAL SYSTEM PROCE
17. DE2 that can handle one master and one slave device each The IDE hard drives and CD ROM drives are attached to the sys tem board via signal cables that connect to two 40 pin BERG connectors labeled ID1 and ID2 Traditionally cables used with internal disk drives have been flat ribbon cables However newer rounded cables are available for con necting disk drives to the system board The connectors at the ends of the cables are the same but the rounded cables are supposed to take up less space provide 87 1 0 Ports better air flow through the case and be more flexible so they are easier to work with There are several versions of the PATA IDE interface Fortunately most of these versions are concerned only with the software and drivers that control the flow of information through the interface System boards that used the original PATA IDE specification provided one 40 pin connector on the board and offered a single IDE channel that could control two IDE devices one master and one slave Eventually system boards that sup port the Enhanced IDE EIDE standards for communications and feature two physical IDE connectors were introduced to the market Each EIDE channel is capable of handling its own master and slave devices Over time the EIDE interface has been redefined to provide faster transfer rates as well as to handle larger storage capacities EIDE interfaces can also be used to control drive units such as a tape or CD ROM The
18. HIGH amp DEFINITION AUDIO s i 500 MBs 2 EACH X1 T mom 0 We 2 SAS 60 MBs 133 MBs INTEL MATRIX STORAGE TECHNOLOGY INTEL PRO 1 000 UAN OPTIONAL INTEIFACTIVE MANAGEMENT TECHNOLOGY OPTIONAL FIGURE 2 10 An Intel dual core processor chipset Chipsets designed to support the Pentium Extreme Edition processors with hyperthreading technology include the Intel 975X 955X 945G 925XE 925X 70 Chapter 2 PC System Boards and 915G Express chipsets Figure 2 11 depicts the block diagram of a typical Pentium Extreme Edition processor chipset This particular chipset is the 975X chipset designed for high performance gaming multimedia and business appli cations Notice the extremely fast front side bus capabilities the number of PCle options available and the number of different I O options supported INTEL PENTIUM PROCESSOR EDITION PCle X16 GRAPHICS OR PCIeYX8 GRAPHICS f l l l l I l l DDR2 DDR2 l QOEM EE ES d INTEL HIGH 7 DEFINITION AUDIO df EN 2 5398491 ni w 500 MBs jJ b EACH X1 Ce mom 133 MBs INTEL MATRIX STORAGE TECHNOLOGY We XS NS 60 MBs IINTEUSPRO 1000 IAN OPTIONAL INTERACTIVE MANAGEMENT TECHNOUOGY OPTIONAL FIGURE 2 11 An Intel Pentium Extreme Edition chipset The 910GL Express chipset is used with the Intel Celeron D processor Likew
19. OS However they also provide an entry for user definable drive settings Systems with PATA drive capabilities support up to four IDE drives In older BIOS ver sions the CMOS typically did not display information about CD ROM drives or SCSI devices however newer versions show both types of devices when run ning in autodetect mode When the Auto Detect selection is chosen the BIOS attempts to detect IDE devices in the system during the POST process and to determine the specifica tions and optimum operating modes for those devices The drive specifications can also be selected from a built in list of drive parameters or they can be entered directly using the User option at the end of the list Four translation modes can be selected for each drive type Auto Normal Large and LBA In Auto mode the BIOS attempts to determine the best oper ating mode for the drive In Normal mode the BIOS will support a maximum Cyl Hds Sec CHS setting of 1024 16 63 For larger drives greater than 1 024 cylinders or 504MB the Large and LBA modes are used The Large option can be used with large drives that do not sup port logical block addressing LBA techniques For drives that do support log ical block addressing the LBA mode should be selected In this mode the IDE controller converts the sector head cylinder address into a physical block address that improves data throughput Care must be taken when changing the 100 Chapter 2 PC System Boar
20. SSOR FAN S i e 04 _ POWER SUPPLY PORT EXPANSION CA GONNECTION CONNECTION SLOTS SURROUND A SOUND __ meamea ee OUT PORTS PORT PARALLEL PORT IEE ESI 394A CONNECTOR PS 2 SERIAL PORTA KEYBOARD PORT FIGURE 2 6 Typical BTX back panel layout DIGITAL AUDIO OUT COAXIAL USB USB MIC IN PORTS PORTS RETASKING TWO TWO JACK B 66 Chapter 2 PC System Boards Low Profile Form Factors Low profile cases employ short backplanes to provide a lower profile than tra ditional desktop units In low profile cases the adapter cards are mounted hor izontally on the backplane card that extends from an expansion slot on the motherboard The expansion slot openings in the back panel of the case are hor izontal as well To accommodate the lower profiles special lowered power sup ply versions have also been developed The low profile extended LPX form factor also referred to as the slim line form factor was designed to reduce the height of the system unit As such the specification applied to system unit cases power supply units and expansion cards LPX never became an official standard but it gained enough industry sup port that millions of cases and power supply units were produced LPX system boards typically incorporated built in video so that no adapter card was needed
21. Terms you ll need to understand SS NN SNSNSNNSNNNNMA CHAP TWO PC System Boards Slot 1 Slot 2 Slot A Socket A Socket 7 Socket 8 Socket 423 Socket 478 Socket 370 Socket LGA775 Socket 939 PCI slots PCI X slots Techniques to master V V V V Essentials 1 1 Identify the fun damental principles of using personal computers Identify the names purposes and characteristics of mother boards Form factor for example ATX BTX micro ATX NLX Components V Integrated 1 05 for exam ple sound video USB serial IEEE 1394 FireWire parallel NIC modem V Memory slots for exam ple RIMM DIMM SS SN SN SN NNNM NS PCle sLots AGP slots Chipsets USB Universal Serial Bus interface FireWire interface AMR audio modem riser slots CNR communication network riser slots PATA interfaces SATA interfaces SCSI interfaces CMOS setup Processor sockets External cache memory Bus architecture Bus slots for example PCI AGP PCIE AMR CNR EIDE PATA SATA SCSI technology Chipsets BIOS CMOS Firmware Riser card daughter board 5 lt NNN 60 Chapter 2 PC System Boards Introduction This chapter covers the motherboard areas of the CompTIA A Certification Essentials examination under Objective 1 1 The system board is the main com ponent in a PC compatible microcomputer system The system board contains the components that form the basis of the co
22. The black connector should be connected to the master device and the gray connector is used for a slave device if one is used on the same IDE channel as illustrated in Figure 2 21 88 Chapter 2 PC System Boards HDD MASTER DRIVE CD RW COLOR SLAVE DRIVE STRIPE PIN 1 he tn IDE CONNECTION IDE SIGNAL CABLE BLUE SYSTEM BOARD FIGURE 2 21 PATA drive connections This color code is just a suggestion physical configuration jumpers on the devices control the actual designation of master and slave devices If PATA devices are not connected according to the color code they will still fanction properly Procedures for configuring PATA devices are covered in detail in Chapter 7 Installing Upgrading Configuring and Optimizing PC Components Serial ATA Connections As with all other parallel I O schemes the PATA specification eventually ran into performance limitations speed and distance associated with parallel trans missions The SATA interface specification was designed to replace the PATA interface and overcome its electrical constraints Although it replaces the phys ical interface connection and cabling structures the SATA specification remains compatible with the supporting ATA software embedded in existing operating systems Figure 2 22 depicts the flat 7 pin SATA signal cable connector and its configu ration Four of the
23. What do you have to do to make this modem work in your plug and play system Integrated Peripherals Setup Functions In most Pentium based systems the standard I O functions are configured through the BIOS Integrated Peripherals screen depicted in Figure 2 26 This screen provides configuration and enabling settings for the system board s IDE drive connections floppy disk drive controller onboard UARTs and onboard parallel port ROM PCI ISA BIOS 2ASKFR3B INTEGRATED PERIPHERALS SETUP AWARD SOFTWARE INC On Chip IDE Controller Enabled Parallel Port Mode Normal The 2nd channel IDE Enabled IDE Primary Master PIO Auto IDE Primary Slave PIO Auto IDE Secondary Master PIO Auto IDE Secondary Slave PIO Auto IDE Primary Master FIFO Enabled IDE Primary Slave FIFO Disabled IDE Secondary Master FIFO Disabled IDE Secondary Slave FIFO Disabled IDE HDD Block Mode Enabled Onboard FDC Controller Enabled Onboard UART 1 Auto UART 1 Operation mode Standard Quit gt lt Select Item Onboard UART 2 Auto Help PU PD Modify UART 2 Operation mode Standard Old Values Shift F2 Color Load BIOS Defaults Onboard Parallel Port 378 IRQ7 Load Setup Defaults FIGURE 2 26 The Integrated Peripherals screen IDE Functions The Integrated Peripherals screen is used to enable the onboard IDE controller As mentioned earlier the second IDE channel can be enabled or disabled inde penden
24. addition a 462 pin ZIF socket specification was adopted for the PGA ver sions of its Athlon and Duron processors This has been followed by a line of advanced sockets to keep pace with the updated features of the AMD processors gt Socket 563 Athon XP M low power mobile gt Socket 754 Athlon 64 gt Socket 939 Athlon 64 Athlon 64 FX gt Socket 940 Opteron Athlon 64 FX gt Socket 462 Socket A Athlon Duron Athlon XP Athlon XP M Athlon and Sepron gt Socket AM2 A 940 pin socket also known as Socket M2 replaces the current Socket 754 and 939 offerings Athlon 64 Athlon 64 FX and Athlon 64 X2 94 Chapter 2 PC System Boards gt Socket SI A 638 pin mobile processor socket that replaces the Socket 754 for Athlon 64 mobile processors and future dual core AMD processors gt Socket F A 1207 pin socket that replaces the Socket 940 for dual processor applications Table 2 3 summarizes the attributes of the various industry socket and slot spec ifications TABLE 2 3 NUMBER Socket 1 Socket 2 Socket 3 Socket 4 Socket 5 Socket 6 Socket 7 Socket 8 Slot 1 Slot 2 Super Socket 7 Socket 370 Slot A Socket A Socket 423 Socket 478 Socket 603 PINS 169 PGA 238 PGA 237 PGA 237 PGA 320 SPGA 235 PGA 321 SPGA 387 SPGA 242 SECC SEPP 330 SECC 2 321 SPGA 370 SPGA 242 Slot A 462 SPGA 423 FC PGA 478 FC PGA 603 INT PGA Industry Socket Specificat
25. al circumstances a full featured antivirus utility should be run on the system CAUTION The virus warning utility should be enabled for normal operations however it should be turned off when you conduct an upgrade to the operating system The built in virus warn ing utility checks the drive s boot sector for changes The changes that the new operating system will attempt to make to the boot sector will be interpreted as a virus and the utili ty will act to prevent the upgrade from occurring EXAM ALERT You should know that BIOS virus detection functions should be disabled when perform ing an operating system upgrade 101 CMOS RAM This screen is used to configure different bootup options These options include establishing the system s bootup sequence Most BIOS versions typically provide user definable boot sequences for up to four devices The most commonly used sequence checks the first hard drive as the first boot source Newer BIOS ver sions can be configured so the system checks the CD ROM drive for a boot sec tor first You should enable the CD ROM as the primary boot option when you are installing an operating system or when the system will not boot from the HDD In these cases the operating system CD can be used to start the system for installation or troubleshooting purposes EXAM ALERT Know the possible disk seek configuration possibilities and be aware of how they might affect the system in different c
26. ards and the system s available resources the PnP routine assigns system resources to the cards as required 76 Chapter 2 PC System Boards Because the PnP process has no method for reconfiguring legacy devices during the resource assignment phase it begins by assigning resources such as IRQ assignments to these devices before servicing the system s PnP devices Likewise when the BIOS detects the presence of a new device during the detec tion phase it disables the resource settings of its existing cards checks to deter mine what resources are required and available and then reallocates the system s resources as necessary EXAM ALERT Know the process the PnP system employs to allocate resources to a new device in an existing system Depending on the CMOS settings available with a particular PCI chipset the startup procedure may be set up to configure and activate all the PnP devices at startup With other chipsets it may also be possible to check all cards but enable only those actually needed for startup Some CMOS routines contain several user definable PCI configuration settings Typically these settings should be left in default positions The rare occasion for changing a PCI setting occurs when directed to do so by a product s installation guide Systems may in theory contain an unlimited number of PCI slots Only four slots are included on most system boards because of signal loading considera tions The PCI b
27. be the case is where the physical edge connector does not match the physical connector AGP Slots Many ATX system board designs include an advanced Accelerated Graphics Port AGP interface for video graphics The AGP interface is a variation of the PCI bus design that has been modified to handle the intense data throughput associated with 3D graphics EXAM ALERT Know what type of device is plugged into an AGP slot 81 Expansion Slots The AGP specification was introduced by Intel to provide a 32 bit video chan nel that runs at 66MHz in basic 1x video mode The standard also supports three high speed modes 2x 5 33MBps 4x 1 07GBps and 8x 2 1GBps The AGP standard provides for a direct channel between the AGP graphic con troller and the system s main memory instead of using the expansion buses for video data This removes the video data traffic from the PCI buses The speed provided by this direct link permits video data to be stored in system RAM instead of in special video memory System boards designed for portable systems and single board systems may incorporate the AGP function directly into the board without using a slot connector As illustrated in Figure 2 16 three types of slot connectors have been used to deliver the AGP function for system boards used in desktop and tower units The system board typically features a single slot that is supported by a Pentium AGP compliant chipset The original slot configuration
28. designed to support the register structure of a particular chipset One of the major functions provided by the BIOS is the Chipset Features con figuration screen in the CMOS setup routine described later in this chapter Technicians can use this tool to optimize the system settings to provide maxi mum internal performance However these settings tend to be very technical and require an extensive understanding of the specific system s component structure to configure Therefore replacing a ROM BIOS chip on a system board is not as simple as placing another ROM BIOS IC integrated circuit in 69 System Board Form Factors the socket The replacement BIOS must have correct information for the spe cific chipset it is being used with Dual Core Intel Chipsets Intel has also introduced a new series of system board chipsets to support the Pentium D line of processors These include the Intel 975X 955X 945G 945GZ 945P and 945PL Express chipsets Figure 2 10 depicts the block dia gram of a typical Pentium D processor chipset The chipset described in the fig ure is the 955X chipset This chipset is primarily intended to support Pentium D and Pentium Extreme Edition processors However Intel also lists it as sup porting all other Intel microprocessors using the LGA775 socket wv CUINTEU PENTIUM PROCESSOR EDITION cam lt 815 GBS T sr E pelt PCIe X16 2102955X9 GRAPHICS SES mc T INTEL
29. drive Access limited to the first 504MB of the drive Slower drive access times Deletion of the MBR Which CMOS functions should be disabled when performing an operating system upgrade O O O O A EPP and ECP B PnP resource allocation C D RAM memory checks BIOS virus detection functions When your computer boots you want it to search for a boot sector on a floppy a CD ROM drive and then the hard disk drive What boot sequence should you set in CMOS O O O O A A C SCSI B A C CD ROM C D A CD ROM C CD ROM A C 16 17 18 19 20 113 Exam Prep Questions During which portion of the startup process does the BIOS communicate with the sys tem s PnP devices C D During the POST During the initialization phase During the OS bootstrap operation During the CMOS configuration process Which utility must be used to enable the ECP and EPP modes for the parallel port o O Q0 A DMA setup B CMOS setup C D BIOS initialization Printer driver What types of devices can be used with a half duplex bidirectional parallel printer cable Select all that apply O O O O A USB devices B SPP devices C D ECP devices EPP devices What are the effects of forgetting a CMOS password You cannot start the computer B You cannot boot to the operating system C D You cannot
30. ds translation mode setting in CMOS because all data on the drive can be lost in the process In the case of errors detected during the POST process some BIOSs can be set up to halt on different types of errors or to ignore them and continue the boot up process These settings include gt No Errors The POST does not stop for any errors gt All Errors The POST stops for all detected errors and prompts the user for corrective action gt Aseries of All But options The POST stops for all errors except those selected that is all but disk or keyboard errors Finally the screen displays the system s memory usage The values displayed are derived from the POST process and cannot be changed through the menu The BIOS displays the system s total detected RAM base memory extended memo ry and other memory between the 640kB and 1MB marks In most CMOS displays the total memory does not equal the summation of the base and extended memory This is because the BIOS reserves 384kB for shadowing pur poses Newer BIOS versions may show only the total installed system memory Advanced BIOS Features Setup Screen The Advanced BIOS Features Setup screen provides access to options that extend the standard BIOS functions Many BIOSs include a built in virus warn ing utility that produces a warning message whenever a program tries to write to the boot sector of an HDD partition table If a warning message is displayed under norm
31. e whether addresses are intended for devices on the system board in a Peripheral Component Internconnect PCI slot or in one of the system board s other expansion slots It also provides the interface between the PCI bus the IDE Integrated Drive Electronics bus and the ISA bus if present The Super I O controller chip interfaces the standard PC peripherals LPT COM and FDD interfaces to the ISA bus This typical chipset arrangement may vary for a couple of reasons The first is to include a specialized function such as an advanced graphics port AGP or USB interface The second reason is to accommodate changes in bus specifica tions such as PCI X or PCle slots Figure 2 8 shows an advanced Pentium PCI chipset design that includes an AGP slot Notice that the AGP slot is local to the North Bridge meaning that it has very fast access to the microprocessor MEMORY BUS FIGURE 2 8 Pentium chipset with an AGP slot 68 Chapter 2 PC System Boards Figure 2 9 depicts an advanced Pentium PCI chipset that provides advanced PCle expansion buses for multiple links Notice that each PCIe link is attached directly to the South Bridge with the exception of a special PCle link for the high end video display adapter NORTH MEMORY BR ERONIISIDE 3 i A ERDGE BUS MICROPROCESSOR FIGURE 2 9 Advanced Pentium PCle chipset It is normal to consider the ROM BIOS as an integral part of any chipset model because it is
32. e available they are not standard boards and have probably been created to fill the specific needs of a particular application Therefore SCSI devices require that a SCSI host adapter card be installed in most systems The built in SCSI connector on the system board will normally be made through a 50 pin BERG header Like the IDE drives support for the onboard SCSI controller must be established through the CMOS setup utility The sys tem BIOS provides support for the built in SCSI controller through its CMOS setup utility whereas add on adapter cards feature a BIOS extension on the card Figure 2 24 shows typical SCSI connections 91 Processor Socket Specifications 50 PIN SCSI lt PORT 25 PIN SCSI lt PORT s I x M gt gt EEZ mU p D lt A G i 1 50 PIN DEN SCSI CABLE SCSI CABLE 80 PIN SCSI lt PORT EN gt 4 S A EN i oa W P Po Y 5 L CLE E 68 PIN p 68 PIN SCSI CABLE SCSI CABLE FIGURE 2 24 SCSI connections Processor Socket Specifications Intel has always developed lines of upgrade microprocessors for its original offerings These are referred to as OverDrive processors An OverDrive unit may be the same type of microprocessor running at a higher clock speed or it may be an advanced architecture microprocessor designed to operate from the same sock et pin configuration as the original Io accommodate this option Intel c
33. equence in the operating system Control Panel Reconfigure the drive seek sequence in the CMOS setup utility Disconnect the IDE cable to the drive to force the system to boot from the floppy drive Reconfigure the floppy jumpers to make it a bootable drive What type of BIOS password should be set on machines that are open to public use O A B C D User access Remote Access Admin Supervisory You are responsible for computers in your area of the building You need to secure them so that only your employees can access the systems but they cannot change CMOS settings What type of CMOS password should you set for these machines O D User access Remote Access Admin Supervisory Where should you establish an Administrators password on a computer that will be installed in an Internet cafe O D In the CMOS setup utility In the BIOS In Windows If you set a password in this environment users will not be able to access the system 116 Chapter 2 PC System Boards Answers and Explanations 1 10 11 12 13 14 B The PCI bus specification uses multiplexed address and data lines to conserve the pins of the basic 124 pin PCI connector D Because the PnP process has no method for reconfiguring legacy devices during the resource assignment phase it begins by assigning resources such as IRQ assign ments to these devices before
34. flip chip is used to describe a group of microprocessors that have pro visions for attaching a heat sink directly to the microprocessor die The proces sors in this category include the Cyrix Celeron and Pentium Although the PPGA and FC PGA processors will both plug into the 370 socket that does not mean they will work in system board designs for the other specifications 93 Processor Socket Specifications The original P4 was delivered in a Socket 423 configuration Subsequent ver sions have been produced using Socket 478 or flip chip LGA775 sockets Intel has continued to employ the LGA775 socket arrangement for a number of its newer processor designs including gt Pentium 4 2 66 3 800GHz gt Celeron D 2 527 3 333GHz gt Pentium 4 Extreme Edition 3 2GHz 3 400 3 73GHz gt Pentium D 2 80 3 40GHz Intel has also offered a variety of front side bus speed options through this sock et type including 133MHz 533FSB 200MHz 800FSB 266MHz 1066FSB and 333MHz 1333FSB speeds The LGA775 package features 250 power and 273 ground pins to accommodate the processor s 130 watts of power dissipation AMD Slots and Sockets AMD produced a reversed version of the Slot 1 specification for its Athlon processor by turning the contacts of the Slot 1 design around They titled the new design Slot A While serving the same ends as the Slot 1 design the Slot A and Slot 1 microprocessor cartridges are not compatible In
35. from accessing and manipulating the sys tem s configuration settings Challenge Solutions 1 You can potentially upgrade your Pentium II Slot 1 machines to Pentium class microprocessors that will run at up to 1GHz The three bank split bank slot arrangement has separated the memory into a 128MB section for the first slot and only 128MB for the second bank of two slots These devices are not compatible with the organiza tion of the board s slot configuration You need to obtain the system board s user s manual to determine what types and sizes of memory devices can be used If this occurs when you are using the specified types of memory devices you may have a bad DIMM device in one of the slots 119 Challenge Solutions 3 You must go into the CMOS Setup utility and make sure that the CD ROM drive is one of the options selected in the Drive Seek Sequence 4 There are several things that you should do to make this modem work in your system The item we are most interested in at this point is the configuration information required by the CMOS Older BIOS versions required that you manually disable the setting and reserve an IRQ setting for the modem in the PnP PCI Configuration window Windows 2000 and Windows XP operating systems will detect the pres ence of an ISA device and reserve a set of resources for it however you are still required to supply an acceptable device driver program for the device 5 If y
36. had a key located toward the rear of the board These slots were used with 3 3V 2x adapters The second AGP slot version moved the key toward the front of the board so it was not physically compatible with the older AGP adapters These slots were used with 1 5 V 4x adapters The final revision of the AGP slot is the univer sal AGP slot that removes all keys so that it can accept any type of AGP card including universal adapters These slots can be used with 3 3V 1 5V and 0 8V 2x 4x 8x adapters AGP 1 5 V 4X GRAPHICS CARD AGP 1 5 V 4X GRAPHICS CARD AGP 1 5 V 4X GRAPHICS CARD NOT SUPPORTED FIGURE 2 16 AGP slots The newer 8x specification employs a lower supply voltage 0 8 than the 2x and 4x specifications When upgrading an AGP card or a system board containing an AGP slot you should always consult the system board and AGP adapter 82 Chapter 2 PC System Boards card s documentation to verify their compatibility with each other Usually the Chipset Features page of the CMOS setup utility provides user configurable AGP slot parameters that can be used to manually configure the adapter s parameters The default setting for this option is Autodetect In this mode the PnP process will detect the card and assign the correct voltages and maximum speed settings for that type of card Table 2 2 compares the capabilities of the various bus types commonly found in personal computers It is quite appa
37. ight pulses it is normally configured to work with the UART of the system s second serial port This arrangement is established through the Integrated Peripherals page of the CMOS setup utility In this manner the infrared port is assigned the system resources that are usually reserved for the COM2 serial ports To enable the IrDA port the mode for the COM2 UART must be set to auto matic and one of the infrared protocol settings HPSIR or ASKIR must be 106 Chapter 2 PC System Boards selected In addition the transmission duplex mode must be selected usually half duplex The operations of the infrared port and the second serial port are mutually exclusive When the Infrared option is enabled in CMOS the second serial port will be disabled Challenge 5 A customer brings in a computer that has a laser printer and a scanner connected to the parallel port The scanner is connected directly to the computer s parallel port and the printer is connected to the scanner The customer cannot get the scanner to work but the printer operates correctly What two actions should you perform to determine why the scanner does not work correctly Power Management Functions The Power Management fields enable the user to select from different power saving modes Doze Standby Suspend or Hibernate These are green PC compatible power saving modes that step the system incrementally down from maximum power usage The Doze setting cause
38. ions VOLTAGES 5 5 5 3 3V 5V 3 3V 3 3V VRM 2 5V 3 6V VRM 2 2V 3 5V VRM 1 5V 2 5V VRM 1 5V 2 5V VRM 2 0V 3 5V VRM 1 1V 2 5V VRM 1 2V 2 2V VRM 1 2V 2 2V VRM 1 7V VRM 1 5V 1 7V VRM 1 5V 1 7V MICROPROCESSORS 80486 SX DXx DX4 OverDrive 80486 SX DXx Pentium OverDrive 80486 SX DXx Pentium OverDrive Pentium 60 66 60 66 OverDrive Pentium 75 133 Pentium OverDrive Never implemented Pentium 75 200 Pentium OverDrive Pentium Pro Celeron Pentium II Pentium I Xeon AMD K6 2 K6 2 6 111 K6 III Pentium MMX Cyrix Celeron Pentium III AMD Athlon AMD Athlon Duron Pentium IV 1 3GHz 2 0GHz Pentium IV Xeon 1 4GHz 2 2GHz Pentium IV 1 4GHz 2 2GHz 95 DRAM Sockets TABLE 2 3 Continued NUMBER PINS VOLTAGES MICROPROCESSORS Socket 418 418 INT PGA VRM 1 7V Itanium Intel 733MHz 800MHz FC LGA775 775 LGA 1 2V 1 4V Pentium 4 Extreme Socket T Edition D Celeron D Socket 563 563 microPGA 1 5 1 75V Athlon XP M Socket 754 754 PGA 0 8 1 55V Athon 64 Socket 939 939 PGA 0 8 1 55V Athon 64 Athon 64 FX Socket 940 940 PGA 0 8 1 55V Opteron Athon 64 FX Challenge 1 Your company does not want to replace all of its computers at this time In fact what it really wants to do is spend a little money to upgrade all its computers as much as it can now and wait as long as possible to replace them Because you are the Technical Service Manager the c
39. ircumstances Challenge 3 Your system will not boot up to the hard drive so you place a bootable CD ROM in the drive and try to restart the system You watch the startup sequence closely and discover that the system does not appear to check the CD ROM drive for a disc What should you do to get the system to look for a disc in the CD ROM drive as part of the bootup activi ties Advanced Chipset Features Setup Functions The Advanced Chipset Features screen contains advanced setting information that system designers and service personnel use to optimize the chipset The options and submenus associated with this page can vary greatly from chipset to chipset The options that you can configure here depend on the functions the chipset provides for example FSB options processor speed voltage options AGP configurations thermal throttling memory timing options and so on The Auto Configuration option selects predetermined optimal values for the chipset to start with When this feature is enabled many of the screen s fields are not available to the user When this setting is disabled the chipset s setup parameters are obtained from the system s CMOS RAM Many of the system s memory configuration parameters are established in this screen PnP PCI Configuration Functions In most newer PCs the BIOS the peripheral devices and the operating system employ Plug and Play technology that enables the system to automatically 102 Chap
40. is located in the system and what its resource needs are B One of the onboard 1 0 functions supported through the CMOS Setup utility includes selecting the operating modes for the parallel port The parallel printer port can be con figured for normal PC AT compatible standard parallel port SPP operation for extended bidirectional operation extended parallel port or EPP for fast buffered bidi rectional operation extended capabilities port or ECP or for combined operation The normal setting should be selected unless both the port hardware and the driver software support EPP and or ECP operation C D Because both of the advanced parallel port modes EPP and ECP operate in a bidirectional half duplex manner they require an IEEE 1284 compliant cable Standard parallel cables designed for older SPP operations may not support these qualities B Because the CMOS password controls access to all parts of the system even before the bootup process occurs there is some inconvenience in the event that the user for gets his or her password When this occurs it will be impossible to gain access to the system without completely resetting the content of the CMOS RAM D On some system boards resetting the content of the CMOS can be accomplished by shorting a special pair of jumpers on the board With other systems you will need to remove or short across the backup battery to reset the CMOS information In ATX sys tems it
41. ise a low power chipset has been developed to support the Core Duo processors in mobile computing environments This chipset is the Intel 945GTExpress chipset Figure 2 12 depicts the block diagram of the Pentium Celeron D processor chipset Notice the reduced set of features compared to the previous chipset architectures Also notice the reduced speeds associated with the major buses and I O connections 71 System Board Form Factors INTEL RENTIUM CELERON D PROCESSOR 900 GRAPHICS INTEL HIGH DEFINITION AUDIO 500 MBs EACH X1 DGIePX SHOTS 133 MBs INTEL MATRIX STORAGE TECHNOUOGY 5 PORT FIGURE 2 12 Intel Pentium Celeron D chipset Table 2 1 compares the attributes of the different dual core Pentium chipsets TABLE 2 1 Dual Core Pentium Chipset Specifications PRODUCT FSB MEMORY EXPANSION DISK DRIVE SPEEDS TYPES BUSES SUPPORT Pentium D 975X Express 800 1066 DDR2 533 PCle x SATA 3Gbps 667 8GB 16 x1 945G Express 533 800 DDR2 400 PCle x SATA 1066 533 667 16 x1 4 6 3Gbps 4 945GZ Express 533 800 DDR2 400 PCle x SATA 533 1 4 6 3Gbps 4 72 Chapter 2 PC System Boards TABLE 2 1 Continued PRODUCT FSB MEMORY EXPANSION DISK DRIVE SPEEDS TYPES BUSES SUPPORT 945P Express 533 800 DDR2 400 PCle x SATA 1066 533 667 16 x1 4 6 3Gbps 4 945PL Express 533 800 DDR2 400 PCle x SATA 533 16 x1 4 6 3Gbps 4 Pentium EE 975X Express 8
42. m MMX and Pentium Pro Although the Intel Slot 1 design was originally developed for the Pentium II it also serves the Celeron and Pentium III processor designs Like Socket 7 the Slot 1 specification provides for variable processor core voltages 2 8 to 3 3 that permit faster operation and reduced power consumption In addition some sup pliers have created daughter boards containing the Pentium Pro processor that can be plugged into the Slot 1 connector This combination Socket 8 Slot 1 device is referred to as a s otket processor The Slot 2 specification from Intel expands the Slot 1 SECC technology to a 330 contact SECC 2 cartridge used with the Intel Xeon processor In a departure from its proprietary slot connector development Intel reversed direction and introduced a new ZIF socket standard called Socket 370 for use with its Celeron processor There are two versions of the Socket 370 specifica tion The first is the PPGA 370 variation intended for use with the Plastic Pin Grid Array PPGA version of the Celeron CPUs The other is the Flip Chip Pin Grid Array FC PGA version When Intel retreated from the slot processor designs and returned to sockets for its processors it abandoned the linear socket numbering system and began referring to the socket by its pin count for example Socket 370 is a socket that has 370 pins the com pany originating the use of the socket gets to specify what each pin represents The term
43. mputer system Even though the system board s physical structure has changed over time its logical structure has remained relatively constant Since the original PC the system board has con tained the microprocessor its support devices the system s primary memory units and the expansion slot connectors Technicians must be aware of the characteristics of different types of system boards in the marketplace This will enable them to make intelligent choices about repairing upgrading or exchanging system boards System Board Form Factors Although the term form factor generally refers to the physical size and shape of a device with system boards it also refers to their case style and power supply compatibility as well as to their I O connection placement schemes These fac tors must be considered when assembling a new system from components and in repair and upgrade situations where the system board must be replaced One of the first considerations when installing or replacing a system board is whether it will physically fit form factor and work with the other system com ponents compatibility In both of these situations the following basic issues must be dealt with the system board s form factor its case style and its power supply connection type CompTIA s 2006 A exam deals only with ATX BTX and NLX form factors ATX System Boards Intel developed the ATX form factor for Pentium based systems as an evoluti
44. n on the battery contacts Clean the contacts with a pencil eraser and retry the battery If that doesn t work try replacing the battery Next you can try replacing the RTC module If this does not correct the timekeeping problem the electronic circuitry that recharges the battery may be defective and in this case you will need a new motherboard A Care must be taken when changing the disk drive translation mode setting in CMOS because all data on the drive can be lost in the process C BIOS antivirus functions should be turned off when conducting an upgrade to the operating system The built in virus warning utility checks the drive s boot sector for changes The changes that the new operating system will attempt to make to the boot sector will be interpreted as a virus and the utility will act to prevent the upgrade from occurring c 16 17 18 19 20 21 22 117 Answers and Explanations D The BIOS Features Setup screen is used to configure different bootup options These options include establishing the system s bootup sequence The sequence can be set so that the system checks the floppy drive A for a boot sector first or so that it checks the hard drive C without checking the floppy drive Other boot options include CD ROM drives or a SCSI drive B The PnP device communicates with the BIOS during the initialization phase of the startup to tell the system what type of device it is where it
45. nd venting the heated air from the vents on the sides of the module BTX Options The BTX specification offers four board widths that share common core design characteristics The length of all the board types is 266 7mm One of the core design characteristics is that in each version the expansion slots have been moved to the right side of the BTX boards making BTX designs incompatible with other PC form factors The standard BTX board versions are described in Figure 2 4 and include the following gt PicoBTX This is the smallest BTX variation at a width of 203 2mm It includes only a single expansion slot gt NanoBTX This BTX version increases the board width to 223 53mm and provides for two expansion slots gt Micro BTX This medium size BTX version includes four expansion slots on a board that is increased to a width of 264 16mm gt BTX The full size BTX specification extends the number of expansion slots from the four in the smaller variations to a total of seven The board width for the full version is 325 12mm 64 Chapter 2 PC System Boards PicoBTX NanoBTX DIMM SLOTS MicroBTX DIMM SLOTS FIGURE 2 4 Standard BTX size variations BTX system boards routinely include SATA interface connections USB 2 0 ports and PCI Express PCle expansion slots The larger the board the more adapter slots and slot types are included Typical expansion slots used in BTX systems include PCI 5V PCI 3 3V AGP 3 3V AGP
46. nstalled in one of the PCI X slots determines the operating speed for all the PCI devices Although these versions offered some improvements over previous PCI versions they have never been widely used in desktop PCs or network workstations Instead boards with these slots have typically been used in more powerful network server computers PCI Express Originally there was a PCI X 1066 expansion slot version envisioned However as signal speed increases in parallel bus connections it becomes much more dif ficult to reliably transmit and receive data The electrical quantities associated with insulated parallel conductors eventually outweigh the advantages of send ing multiple bits of data at the same time When this point is reached in any type of communications setting the answer is always to implement some type of seri al one bit at a time using one communication path method of moving the information from point A to point B The PCI specification shifted to a serial PCI expansion scheme called PCI Express PCIe The Pentium PCle chipset employs the same software driver support as traditional PCI interfaces However under PCle the data moving back and forth across the bus is formed into serialized packets before being sent and is then converted back to parallel format after it has been received The basic PCIe architecture employs two low voltage differential signal LVDS pairs of data lines that carry data back and forth at rates up
47. o be changed If changes are made that disable the system pressing the Insert key on reset will override the settings and start the system with default values The standard CMOS setup screens from various BIOS manufacturers all pro vide the same basic information They can be used to set the system clock cal endar establish disk drive parameters and video display type and specify which types of errors will halt the system during the POST Time and Date PC chipsets include a Real Time Clock RTC function that keeps track of time and date information for the system During the startup process the operating system acquires the time and date information from the CMOS RTC module This information is updated in the system once every second The CMOS uses military time settings for example 13 00 00 1 p m The PgUp and PgDn keys are used to change the setting after it has been selected using the arrow keys Most BIOS versions support daylight saving time by adding an hour when daylight saving time begins and subtracting it when stan dard time returns All system boards employ a rechargeable battery to maintain the system s con figuration information when it is turned off In newer systems the most com mon battery type is a replaceable 2032 coin cell battery These are plentiful and easy to change if they become defective However in other systems there are no rechargeable batteries for the CMOS storage Instead the CMOS storage
48. ompany has asked you for a plan to upgrade the systems You know that nearly all the systems in the company are Pentium II 350MHz machines What is the most current fastest upgrade you can recommend to your board of directors DRAM Sockets Pentium system boards supply special 168 pin 184 pin or 240 pin snap in sockets to hold the system s SDRAM DDR DRAM or DDR2 DRAM DIMMs The sockets and DIMMs are keyed so that they cannot be plugged in backward DIMM sockets are quite distinctive in that they are typically arranged side by side and may involve between three and four slots However they can be locat ed anywhere on the system board Some system boards feature a three DIMM slot arrangement referred to as a split bank arrangement When you are working with these boards you must refer to their user s manual to determine what types of memory can be used because split bank arrangements use a different specification for DIMM slot 1 than for DIMM slots 2 and 3 The odd slot is usually organized into one bank whereas the other two slots combine to form the second bank If you are not careful when populating these slots you may create a situation in which the system s memory controller cannot access all the installed RAM 96 Chapter 2 PC System Boards EXAM ALERT Be aware of situations that will cause the system to see less than the actual amount of installed RAM Challenge 2 You have been assigned to upgrade the memor
49. on of the older Baby AT form factor that first integrated the standard I O functions onto the system board It has been the predominant PC form factor for some time The ATX specification basically rotates the Baby AT form factor by 90 degrees relocates the power supply connection and moves the microprocessor and memory modules away from the expansion slots 61 System Board Form Factors Figure 2 1 depicts a Pentium based ATX system board that directly supports the floppy disk drive FDD hard disk drive HDD serial and parallel ports The board is 12 inches 305mm wide and 9 6 inches 244mm long A revised mini ATX specification allows for 11 2 inch by 8 2 inch system boards The mounting hole patterns for the ATX and mini ATX system boards require a case that can accommodate ATX boards CONNECTORS RAM SLOTS POWER CONNECTOR FRONT PANEL CONNECTIONS FIGURE 2 1 An ATX Pentium system board EXAM ALERT Be able to identify the major components of an ATX system board from a graphical representation The power supply orientation enables a single fan to be used to cool the system This feature results in reduced cost reduced system noise and improved relia bility The relocated microprocessor and memory modules enable full length adapter cards to be used in the expansion slots while providing easy upgrading of the microprocessor RAM and I O devices The fully implemented ATX format also has specifications for the
50. onal modes are enabled The functions of the port s pins are rede fined under the EPP specification When the EPP mode is enabled the port can operate either as a standard bidirectional SPP parallel port or as a bidirection al EPP port The software controlling the port will specify which type of oper ation is required The ECP mode provides a number of advantages over the SPP and EPP modes In particular it offers higher performance than either of the other modes As with the EPP mode the pins of the interface are redefined when ECP mode is selected in the system s CMOS The ECP port is compatible with the standard LPT port and is used in the same manner when no ECP operations are called for However it also supports high throughput DMA operations for both for ward and reverse direction transfers Because both of the advanced parallel port modes operate in a bidirectional half duplex manner they require an IEEE 1284 compliant cable Standard par allel cables designed for older SPP operations may not support these qualities EXAM ALERT Be aware that a non IEEE 1284 rated parallel printer cable should not be used with bidirectional EPP or ECP devices Infrared Port Operation Infrared Data Association IrDA ports provide short distance wireless connec tions for different IrDA compliant devices such as printers and personal digital assistants Because the IrDA port communicates by sending and receiving a seri al stream of l
51. ou consider the nature of the two devices you will realize that the scanner is basically an input device actually a bidirectional device so its data must move back to the parallel port whereas the printer is an out put device so information normally travels from the port to the printer Check the parallel cables to make sure that they are IEEE 1284 compli ant The port must be configured for bidirectional support in the CMOS Check the CMOS settings to make sure that EPP or ECP modes are selected
52. peripheral devices are running at still another speed In Pentium processors a parallel bus called the Back Side Bus BSB connects the microprocessor with its internal L2 cache The chipset devices are responsible for coordinating data and control signal flow between the different buses much like highways and streets where traffic trav els at different speeds The devices in the chipset act as on off ramps and stop lights to effectively coordinate information movement across the buses For example with a current Pentium system board the processor may run at 3 0GHz internally while the front side bus runs at 800M Hz 200 MHz x 4 the PCI bus runs at 33 MHz and the IDE bus runs at 100MHz Expansion Slots The system s expansion slots provide the connecting point for most of its I O devices Interface cards communicate with the system through the extended microprocessor buses made available through these slots The PCI expansion bus specification has become the dominant expansion bus and slot configuration for PCs Continued advancement of the PCI architecture has prevented it from being replaced by another type of bus slot architecture The original ATX Pentium class system boards contained a mixture of ISA and PCI slots Subsequent generations added AMR or CDR slots for specialized audio modem functions Most of these designs also added an AGP slot to sup port high speed video display functions Current ATX and BTX designs have completel
53. provement has been developed using a new slot layout for PCI 2 3 This slot is similar to the PCI 66 32 64 intermediate slot in size and appearance However it is keyed in such a manner that only adapter cards designed for this slot or universal PCI cards can be inserted The slot also fea tures a reduced 3 3Vdc power supply voltage to decrease signal interference lev els generated by the 66MHz operations PCI Configuration The PCI standard is part of the PnP hardware standard As such the system s BIOS and system software must support the PCI standard Although the PCI function is self configuring many of its settings can be viewed and altered through the CMOS setup utility 75 Expansion Slots FIGURE 2 13 32 bit and 64 bit PCI slots During a portion of the bootup known as the detection phase the PnP compatible BIOS checks the system for devices installed in the expansion slots to see what types they are how they are configured and which slots they are in For PnP compatible I O cards this information is held in a ROM device on the adapter card The BIOS reads the information from all the cards and then assigns each adapter a handle logical name in the PnP Registry It then stores the configu ration information for the various adapters in the Registry as well Next the BIOS compares the adapter information to the system s basic config uration in search of resource conflicts After evaluating the requirements of the c
54. rate in a bidirectional half duplex manner they require an IEEE 1284 compliant cable Standard parallel cables designed for older SPP operations may not support these qualities B The Drive A option in the Drive Seek Sequence setting should be enabled if the sys tem cannot boot to the hard disk drive and you have a clean boot disk or emergency repair floppy If you disable the A seek function in the CMOS setup utility by not selecting it as part of the boot seek sequence you will not be able to use the A drive to troubleshoot hard drive problems The system then would never access the floppy drive to see if it had a bootable disk in it however you can always enter the CMOS setup utility and include it as part of the troubleshooting process D The Supervisory password is used to control access to the system s CMOS setup utility Because this system is opened for public use setting a User password would prevent users from accessing the system The Supervisory password will prevent intentional malicious access to the CMOS where users could disable the system A The User password option enables you to establish password access to the systems that you can share with your employees This will prevent other employees from accessing the systems without giving your employees access to the CMOS setup utility A The first line of system protection in this situation is setting a Supervisory password in the CMOS Setup utility to prevent users
55. re with BIOS Defaults The autoconfiguration power on defaults provide the most conservative system options from the BIOS and the most effective method of detecting BIOS related system problems These settings replace any user entered configuration infor mation in the CMOS setup registers disabling the turbo speed mode turning off all memory caching and setting all wait states to maximum thus enabling the most basic part of the system for starting If these default values fail to boot the system it indicates possible hardware problems such as incorrect jumper settings or bad components If you have entered an improper configuration setting and cannot determine which setting is causing the problem using the autoconfiguration with the BIOS defaults provides more flexibility than the power on option This selection also 98 Chapter 2 PC System Boards replaces the entered configuration settings with a new set of parameters from the BIOS and likely gets you back into the CMOS setup screen so that you can track down the problem This is also the recommended starting point for opti mizing the system s operation CAUTION Set Values with Caution The settings in these menus enable the system to be config ured and optimized for specific functions and devices The default values are generally recommended for normal operation Because incorrect setup values can cause the system to fail you should change only setup values that really need t
56. reated specifications for eight socket designs designated Socket 1 through Socket 8 The specifications for Socket 1 through Socket 3 were developed for 80486SX 80486DX and 80486 OverDrive versions that use different pin numbers and power supply requirements Likewise the Socket 4 through Socket 6 specifica tions deal with various Pentium and OverDrive units that have different speeds and power supply requirements The Socket 7 specification enabled system boards to be configured for different types and versions of microprocessors using different internal core and FSB operating speeds Its design includes provision for a Voltage Regulator Module VRM to allow various power settings to be implemented through the socket 92 Chapter 2 PC System Boards The Socket 7 specification corresponds to the second generation of Pentium devices that employ SPGA packaging It is compatible with the Socket 5 straight row PGA specification that the first generation Pentium processors employed Finally the Socket 8 specification is specific to the Pentium Pro processor An upgraded Socket 7 specification referred to as Super Socket 7 was devel oped to extend the use of the Socket 7 physical connector This upgrade added support signals required for implementing AGP slots and the 100MHz front side bus FSB specification Microprocessors designed to use the Super Socket 7 specification include AMD s K6 2 K6 2 and K6 HI along with Intel s Pentiu
57. rent that the data transfer rates possible with each new version increase dramatically The reason this is significant is that the expansion bus is a speed limiting factor for many of the system s operations Every peripheral access made through the expansion slots requires the entire computer to slow down to the operating speed of the bus TABLE 2 2 Expansion Bus Specifications BUS TYPE TRANSFER DATA ADDRESS DMA INT RATE BITS BITS CHANNELS CHANNELS ISA 8MBps 16 24 8 11 PCI 2 132 264MBps 32 64 32 None 3 PCI 2 1 264 528MBps 32 64 32 None 3 PCI X 1 0 1 06GBps 64 64 None 3 PCI X 2 0 2 13 4 26GBps 64 64 None 3 PCle 250MBps per lane Serial None None None AGP 266 533 1 070MBps 32 32 None 3 EXAM ALERT You must be able to identify standard expansion slot types from different ATX system board outline drawings Audio Modem Risers and Communication Networking Risers Intel developed an audio modem standard for system board designs that sepa rates the analog and digital functions of audio sound card and modem devices 83 Expansion Slots This standard includes an expansion slot connection called the Audio Modem Riser AMR and a companion expansion card format known as the Mobile Daughter Card MDC The analog portion of the function is placed on the MDC riser card and the digital functions are maintained on the system board These components are depicted in Figure 2 17 FIGURE 2 17 Audio Modem Riser compo nent
58. s AMR slots are already being replaced in Pentium systems by a new design called the Communications and Networking Riser CNR card depicted in Figure 2 18 This specification improves on the AMR specification by including sup port for advanced V 90 analog modems multichannel audio telephone based dial up networking and USB devices as well as 10 100 ethernet based LAN adapters 84 Chapter 2 PC System Boards FIGURE 12 18 Communications and Networking Riser card components 1 0 Ports Many of the PCs standard I O port circuits have been integrated directly into the system board s chipset and BIOS CMOS structures The corresponding hardware ports were grouped into a standardized block of connections in the ATX specification as illustrated in Figure 2 19 These connectors are placed along the back edge of the system board and extend through the back panel of the system unit The back panels of specific PCs may have all the connections depicted in the figure or they may have some subset of these connections The panel features two 0 25 inch 6 pin PS 2 mini DIN connectors specified for both the mouse and the keyboard The lower connector is designated for keyboards equipped with PS 2 connectors and the upper connector is intended for use with a PS 2 mouse Because these connectors are physically identical it is relatively easy to confuse them compensate for this possibility manufac turers have color coded these connec
59. s the microprocessor clock to slow down after a defined period of inactivity The Standby mode shuts down the hard drive and video after a period of inactivity Everything in the system except the microprocessor shuts down in Suspend mode Certain system events such as IRQ and DRQ activities cause the system to wake up from these modes and resume normal operation In Hibernate mode the system saves the current information in memory to the hard disk drive and shuts down When the sys tem is restored form Hibernate mode the environment is returned to the state it was in when Hibernate mode was initiated PC Health Status The PC Health menu shown in Figure 2 27 displays status information for the critical elements of the system board including the microprocessor tempera ture fan speeds and actual voltage levels The page also enables you to estab lish set points for issuing notifications and alarms when these variables are outside of the desired ranges of operation Temperature monitoring can be as simple as tracking the microprocessor s pack age temperature or it can include monitoring the case temperature in multiple locations Key voltage levels tracked by the BIOS include the microprocessor core voltage the expansion slot voltages and the various voltage levels being provided to the system board by the power supply 107 CMOS RAM Phoenix AwardBIOS CMOS Setup Utility PC Health Status Show PC Health in POST Enabled
60. servicing the system s PnP devices A The AGP interface is a variation of the PCI bus design that has been modified to handle the intense data throughput associated with three dimensional graphics B All Ultra ATA versions support 33 3MBps data rates when used with a standard 40 pin 40 conductor IDE signal cable A Refer to Figures 2 1 For more information see the section ATX System Boards C Refer to Figure 2 1 For more information see the section ATX System Boards B Refer to Figure 2 1 An ATX Pentium system board Along with the 1 0 port connec tions Pentium system boards moved the hard and floppy disk drive controller func tions and interface connections to the system board For more information see section ATX System Boards C Refer to Figure 2 1 An ATX Pentium system board For more information see the section ATX System Boards D Refer to Figure 2 1 An ATX Pentium system board For more information see the section ATX System Boards D Refer to Figure 2 18 Standard ATX back panel connections For more information see the section 1 0 Conenctions B Refer to Figure 2 18 Standard ATX back panel connections For more information see the section I O Ports C If the time is incorrect on a PC system the easiest way to reset it is through the operating system however if the system continually fails to keep good time you should start by checking for corrosio
61. ter 2 PC System Boards determine what hardware devices are installed in the system and allocate system resources to those devices as required to configure and manage them This removes some of the responsibility for system configuration from the user or the technician All three of the system components listed previously must be PnP compliant before automatic configuration can be carried out The BIOS holds information about the system s resource allocations and sup plies it to the operating system as required This information can be displayed through the CMOS PnP PCI Configuration screen The operating system must be PnP compatible to achieve the full benefits of the PnP BIOS In most PCs the standard operating system is Windows 2000 or Windows XP which are both PnP compliant Basically the PnP device communicates with the BIOS during the initialization phase of the startup to tell the system what type of device it is where it is locat ed in the system and what its resource needs are This information is stored on the device in the form of firmware The BIOS stores the PnP information it col lects from the devices in a special section of the CMOS RAM known as the Extended System Configuration Data ESCD area This information is stored in the same manner as standard BIOS settings are stored The BIOS and operating system both access the ESCD area each time the sys tem is restarted to see if any information has changed This enables
62. the BIOS and the operating system to work together in sorting out the needs of the installed devices and assigning them needed system resources EXAM ALERT Know which portion of the BIOS is responsible for implementing the PnP process If no changes have occurred in the contents of the ESCD since the last startup occurred the BIOS will detect this and skip that portion of the boot process When a PnP operating system checks the ESCD to see if any hardware changes have occurred it will react accordingly and record any changes it finds in the hardware portion of its Registry On some occasions the system s PnP logic may not be able to resolve all of its resource needs and a configuration error will occur In these cases the technician or the user will have to manually resolve the configuration problem The BIOS and the operating system typically provide interfaces to the hardware configuration information so that users can manual ly override the system s PnP resource assignments 103 CMOS RAM Challenge 4 Your local area network connection to the Internet crashes often and tends to be down for some time For these occasions you want to establish a dial up connection to the Internet from your office computer Your boss does not want to buy a new PnP modem for your use However you have an old internal ISA modem in your desk drawer and want to install it in your system to perform this function through your office phone connection
63. tly of the first channel provided that the controller has been enabled 104 Chapter 2 PC System Boards Any of the four possible devices attached to the interface can be configured for master or slave operation The system s SATA drives and their operating modes are also enabled and con figured through the CMOS setup utility You can typically select among enabling the PATA interface controller the SATA interface controller or both Because the SATA controller is an integral part of the IDE subsystem you may see options for enabling up to six IDE devices in the CMOS Setup utility The IDE rules still apply to the four PATA devices in the system The IDE HDD Block Mode selection should be set to Enabled for most new hard drives This setting also referred to as Large Block Transfer Multiple Command and Multiple Sector Read Write mode supports LBA disk drive oper ations If the Auto mode option is selected the system will determine which mode is best suited for each device Implementing Ports The other onboard I O functions supported through the CMOS utility can include enabling disabling the FDD controller enabling and configuring the system s onboard USB and IEEE 1394 FireWire ports selecting the logical COM port addressing and operating modes for the system s two built in UARIIS and selecting logical addressing and operating modes for the parallel port Other onboard functions configured through this screen include onboard a
64. tors purple indicates that the connection is for the keyboard and green is used for the mouse 85 1 0 Ports BACK OF UNIT 5 2 USB PRINTER GAME MOUSE PORTS PORT PORT KEYBOARD COM 1 COM2 PORT PORT FIGURE 2 19 Standard ATX back panel connections SPEAKER LINE IN MIC To the right of the keyboard and mouse ports is a DB 9M D shell COM port connector for use with serial devices a DB 25F D shell parallel port connector for SPP EPP and ECP parallel devices and a digital coaxial audio output con nector Next are two stacks of two USB connectors An IEEE 1394 FireWire port tops the first stack These are high speed serial interface ports that allow various peripheral devices to be attached to the system The second stack is topped with an RJ 45 connector to accommodate CATS local area networking These con nectors are keyed so they cannot be misaligned Other integrated I O ports commonly found on the back of PC systems include additional serial ports integrated DB 15F D shell VGA display connectors and 1 8 inch RCA jacks for speakers microphones and line in sources EXAM ALERT You must be able to identify standard 1 0 connection types from different ATX BTX system board drawings by their relative sizes and locations Onboard Disk Drive Connections Pentium system boards provide the system s hard disk CD ROM DVD drive and floppy disk drive controller functions and interface connections
65. udio and local area networking interfaces as well as built in support for game ports and MIDI music ports on those system boards that offer them All newer PCs rely on high speed USB and or IEEE 1394 ports as their major I O connections The controller functions for these ports are typically integrat ed into the system board s chipset circuitry They are also enabled disabled through its CMOS setup utility If the system supports a legacy serial communications port the chipset includes a UART device that can be configured to support half duplex or full duplex transmission modes for dialup networking or to support an infrared communi cations port provided the system board is equipped with one This port enables wireless communications with serial peripheral devices over short distances The parallel printer port can be configured for Standard Parallel Port SPP operation for extended bidirectional operation Enhanced Parallel Port or EPP for fast buffered bidirectional operation Extended Capabilities Port or ECP or for combined ECP EPP operation The normal CMOS setting should be selected unless both the port hardware and driver software support EPP and or ECP operation 105 CMOS RAM EXAM ALERT Remember that ECP and EPP modes for the parallel port must be enabled through the CMOS setup utility Enhanced Parallel Port Operations When EPP mode is selected in the port s configuration register the standard and bidirecti
66. us includes four internal interrupt lines NTa through INTd or INT1 through INT4 that enable each PCI slot to activate up to four differ ent interrupts PCI interrupts should not be confused with the system s IRQ channels although they can be associated with them if required by a particular device In these cases IRQ9 and IRQ10 are typically used PCI X PCI bus versions after PCI 2 3 were given a designation of PCI X along with a description of their operating speeds such as PCI X 66 These PCI X specifi cations are enhanced versions of the 64 bit 66MHz PCI 2 3 bus specification gt PCI X 1 0 was based on the previous PCI 2 3 architecture and offers support for 3 3V and universal PCI cards Therefore conventional 33 66MHz PCI cards can be used in PCI X 1 0 slots Conversely PCI X 1 0 cards could be used in standard PCI slots PCI X 1 0 provides 66 and 133M Hz bus speed options TI Expansion Slots gt PCI X 2 0 was derived from PCI X 1 0 and introduced an Error Correction Code ECC feature to improve data transfer reliability It also introduced two new speed options PCI X 266MHz which provides 2 13GB sec transfer rates and PCI X 533MHz with 4 26 GB sec trans fer rates All the PCI X versions are backward compatible with the original PCI specifi cations that is they employ the same form factors pin outs connector 32 64 bit bus widths and protocols as the original PCI specification However the slowest board i
67. utomatically assess the card in the slot during start up and assign the required number of lanes to the slot The unused lanes are then available for use in other PCIe slots System boards designs may include both traditional PCI and PCIe slots A PCI to PCle bridge translates PCle information into standard PCI signals This bridging enables standard PCI devices to be included in the PCIe system The bridging circuitry is starting to be included in PCIe chipsets On these boards the PCI bridge is part of the South Bridge device In other cases the bridge is included in the adapter card PCle Configuration During the PnP process the PCIe switch portion of the chipset negotiates with any PCIe devices to establish the maximum number of lanes available for the link The outcome of the negotiation depends on three factors gt The number of physical lanes the link can support The number of lanes that the device requires gt The number of lanes the PCIe switch can support If the device such as an advanced PCIe video card contains 16 lanes it will need to be inserted into an x16 slot However if the device has only 8 lanes the PCIe switch will detect this and allocate only the 8 lanes required If the link supports more than 16 lanes the extra lanes will be ignored If the device has more lanes than the link can furnish the device and the switch throttle back to the number of lanes available The one situation where this would not
68. will also be necessary to unplug the power from the commercial outlet to reduce the voltage to the CMOS registers When the content of the CMOS is reset you must manually restore any nondefault CMOS settings being used by the system B The BIOS stores the PnP information it collects from the devices in a special section of the CMOS RAM known as the Extended System Configuration Data ESCD area This information is stored in the same manner as standard BIOS settings are stored The BIOS and the operating system both access the ESCD area each time the system is restarted to see if any information has changed This enables the BIOS and the operat ing system to work together in sorting out the needs of the installed devices and assigning them needed system resources C The Standard CMOS setup screens from various BIOS manufacturers all provide the same basic information For example they can be used to set the date and time via the system clock calendar During the startup process the operating system acquires the time and date information from the CMOS RTC module This information is updated in the system once every second 118 Chapter 2 PC System Boards 23 24 25 26 27 28 29 A The ECP mode supports high throughput DMA operations for both forward and reverse direction transfers A The ECP mode offers higher performance than either the SPP or the EPP mode A Because both of the advanced parallel port modes ope
69. wires are used to form two differential signal pairs and whereas the other three wires are used for shielded grounds The cable is only 0 5 inches wide This feature makes cable routing inside the system unit simpler and provides less resistance to airflow through the case The maxi mum length for an internal SATA cable is specified as 36 inches 1 meter 89 1 0 Ports SATA INTERFACE CONNECTOR SYSTEM BOARD FIGURE 2 22 The Serial ATA interface connector Unlike its PATA counterpart the SATA interface has made provisions for con nections outside the system unit case This type of connection is referred to as the external SATA or eSATA interface Figure 2 23 illustrates the implementation of a single lane external SATA interface An eSATA interface consists of a SATA cable that links the SATA interface on the system board to an eSATA connector on one an expansion slot cover mounted in the rear of the system unit A shield ed eSATA cable is used to connect the drive unit to the slot mounted interface The maximum cable length for the external eSATA cable is 6 feet 2 meters 90 Chapter 2 PC System Boards EXTERNAL HARD DISK DRIVE SATA CABLE SHIELDED SATA CABLE SYSTEM BOARD SLOT MOUNTED SATA INTERFACE FIGURE 2 23 eSATA interface connections SCSI Connections No industry accepted equivalents exist for onboard SCSI adapters Although a few such system board designs ar
70. y discarded the ISA AGP AMR CDR slots and provide different ver sions of the PCI slot that is PCI and PCI X or PCI and different PCIe slot types With the exception of the ISA slot all the other expansion bus specifications mentioned include slot addressing capabilities and reserve memory space to allow for plug and play reconfiguration of each device installed in the system However because no identification or reconfiguration capabilities were designed into the ISA bus specification the presence of ISA compatible slots on the system board can seriously disrupt plug and play operations PCI Local Bus The Peripheral Component Interconnect local bus design incorporates three elements a low cost high performance local bus the automatic configuration of installed expansion cards PnP and the capability to expand with the intro duction of new microprocessors and peripherals The data transfer performance 74 Chapter 2 PC System Boards of the PCI local bus is 132MBps using a 32 bit bus and 264MBps using a 64 bit bus This is accomplished even though the bus has a maximum clock frequency of 33MHz The PCI peripheral device has 256 bytes of onboard memory to hold informa tion as to what type of device it is The peripheral device can be classified as a controller for a mass storage device a network interface a display or other hardware The configuration space also contains control status and latency timer values The latenc
71. y in a number of your office s computers When you open them you discover that they have a three slot DIMM arrangement Also you cannot locate a system board user s manual for these computers You install a 128MB DIMM in each slot When you start the computer you see from the POST that the system recognizes only 256MB of RAM What happened to the other 128MB of RAM and how can you get the system to recognize it CMOS RAM The configuration of every PC compatible system is controlled by settings established in its CMOS setup utility Therefore every technician should be aware of the contents of typical CMOS utilities and be able to properly manip ulate the parameters they contain to achieve a fully functional unit and optimize its performance CMOS Setup Utilities The CMOS setup utility can be accessed during the POST process by pressing a designated key The CMOS setup utility s Main Menu screen similar to the one depicted in Figure 2 25 appears whenever the CMOS setup utility is engaged This menu enables the user to select different configuration functions and exit choices The most used entries include the Standard CMOS Setup BIOS Features Setup and Chipset Features Setup options Selecting these or any of the other Main Menu options will lead you into the corresponding sub menus Other menu items typically include Power Management Setup PnP PCI Configuration Integrated Peripherals and Password Maintenance Services The
72. y timer register on the device determines the length of time that the device can control the bus for bus mastering operations The PCI bus specification uses multiplexed address and data lines to conserve the pins of the basic 124 pin PCI connector Within this connector are signals for control interrupt cache support error reporting and arbitration The original PCI bus employed 32 bit address and data buses Its specification also defined a 64 bit multiplexed address and data bus variation for use with 64 bit processors such as the Pentium Its clock line was originally defined for a maximum frequency of 33 MHz and a 132MBps transfer rate however it can be used with microprocessors operating at higher clock frequencies 66MHz under the PCI 2 1 specification The PCI 2 2 and PCI 2 3 versions of the bus implemented two new slot struc tures to provide a true 64 bit data bus as illustrated in Figure 2 13 The new PCI specification runs at 66MHz to provide a 264MBps data throughput The slot also features a reduced 3 3Vdc power supply voltage to decrease signal interference levels generated by 33MHz operations Adapters placed in the 32 bit section of the PCI 2 2 slot can operate with the 5Vdc or 3 3V supply lev els The back portion of the slot remains pin and signal compatible with the older 32 bit PCI slots It retained its 5Vdc operating voltage to remain com patible with older PCI 1 1 and 2 0 adapters An additional PCI bus im

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