MotherboardsMotherboardsBasic PC Maintenance, Upgrade and RepairBasic PC Maintenance, Upgrade and Repair

Mods 1 & 2Mods 1 & 2

Motherboard BasicsMotherboard Basics Considered to be the most important element of a Considered to be the most important element of a

computer’s designcomputer’s design All major components connect to and transmit data All major components connect to and transmit data

across the motherboardacross the motherboard It is the communication center for input and output It is the communication center for input and output

devices such as memory, CPU, keyboard, mouse, devices such as memory, CPU, keyboard, mouse, parallel port, serial port, monitor and network parallel port, serial port, monitor and network connectionconnection

Also provides the connection points required by the Also provides the connection points required by the fans, speakers, on/off switches, LED indicators and fans, speakers, on/off switches, LED indicators and CMOS batteryCMOS battery

Provides a means for expanding and customizing the Provides a means for expanding and customizing the system by inserting expansion boards into slots system by inserting expansion boards into slots provided as direct connections to the system bus provided as direct connections to the system bus architecturearchitecture

It is also referred to as the It is also referred to as the system board, main system board, main boardboard, and , and planar boardplanar board

Motherboard Motherboard ConstructionConstruction

It provides a physical surface on which to mount It provides a physical surface on which to mount electronic components such as resistors, capacitors, IC electronic components such as resistors, capacitors, IC chips, slots and socketschips, slots and sockets

It is a combination of insulating material and It is a combination of insulating material and electronic circuit paths constructed of small electronic circuit paths constructed of small conductors that run along the surface. These conductors that run along the surface. These conductive paths are known as conductive paths are known as tracestraces

Traces provide the electrical circuit paths between all Traces provide the electrical circuit paths between all the different components mounted on the motherboardthe different components mounted on the motherboard

The traces provide a means of sending and receiving The traces provide a means of sending and receiving data between components, as well as providing voltage data between components, as well as providing voltage and current to low power devicesand current to low power devices

Many of the thin conductors on the motherboard are Many of the thin conductors on the motherboard are grouped together to make up what is referred to as grouped together to make up what is referred to as busbus

A A busbus is a collection of conductors that work together is a collection of conductors that work together for a specific purposefor a specific purpose

Bus ClassificationsBus Classifications There are many types of bus classifications such as There are many types of bus classifications such as data data

busbus, , control buscontrol bus, , memory busmemory bus, , internal businternal bus, , I/O busI/O bus, , address busaddress bus, , local buslocal bus, and , and power buspower bus

Data BusData Bus – Used to move data between components in – Used to move data between components in groups of 8, 16, 32, or 64 bits. The amount of data that groups of 8, 16, 32, or 64 bits. The amount of data that can be moved at one time is referred to as the can be moved at one time is referred to as the bus widthbus width

Control BusControl Bus – a bus which delivers command signals – a bus which delivers command signals from the processor to other devices (i.e. hard disk, from the processor to other devices (i.e. hard disk, modem, etc.)modem, etc.)

Memory BusMemory Bus – a bus that connects directly between the – a bus that connects directly between the memory and the processormemory and the processor

I/O BusI/O Bus – a bus that connects the processor to the – a bus that connects the processor to the expansion slots (also referred to as expansion slots (also referred to as expansion busexpansion bus))

Internal BusInternal Bus – is actually part of the IC circuit inside the – is actually part of the IC circuit inside the CPUCPU

Address BusAddress Bus – A bus system that connects directly with – A bus system that connects directly with the main memory module. It identifies where data is to the main memory module. It identifies where data is to be stored and retrievedbe stored and retrieved

Bus ClassificationsBus Classifications Local BusLocal Bus – a bus system that connects directly to – a bus system that connects directly to

the CPU and provides communications to high-the CPU and provides communications to high-speed devices mounted closely to it (also called the speed devices mounted closely to it (also called the system bus)system bus)

Power BusPower Bus – a bus system that sends electrical – a bus system that sends electrical power for small consumption devices such as power for small consumption devices such as speakers, lights and switchesspeakers, lights and switches

A bus may also be a collection of bus types. For A bus may also be a collection of bus types. For example, the local bus consists of power, data, example, the local bus consists of power, data, control and memory bus lines.control and memory bus lines.

For this reason, the local bus has also been For this reason, the local bus has also been referred to as the system bus or memory bus. Intel referred to as the system bus or memory bus. Intel calls the local bus the calls the local bus the front side bus (FSB)front side bus (FSB)

Expansion Card SlotsExpansion Card Slots Expansion card slots provide a quick and easy method Expansion card slots provide a quick and easy method

of connecting devices directly to the motherboard bus of connecting devices directly to the motherboard bus system in order to modify or customize the computersystem in order to modify or customize the computer

Several types have evolved over the years . . . . Several types have evolved over the years . . . . ISA – Industry Standard ArchitectureISA – Industry Standard Architecture. The oldest bus . The oldest bus

system found on motherboards. 16 bit bus width.system found on motherboards. 16 bit bus width. MCA – Micro Channel ArchitectureMCA – Micro Channel Architecture. Made by IBM. 32 . Made by IBM. 32

bit bus width. Because IBM wanted royalties, MCA bit bus width. Because IBM wanted royalties, MCA became EISAbecame EISA

EISA – Extended Industry Standard ArchitectureEISA – Extended Industry Standard Architecture. . Developed by Compaq, AST Research, Epson, HP, Developed by Compaq, AST Research, Epson, HP, NEC, Olivetti, Tandy, Wyse, and Zenith Data Systems NEC, Olivetti, Tandy, Wyse, and Zenith Data Systems in response to IBM’s MCA. 32 bit bus widthin response to IBM’s MCA. 32 bit bus width

VESA – Video Electronics Standards AssociationVESA – Video Electronics Standards Association. . Higher data transfer rate than MCA or EISA. Became Higher data transfer rate than MCA or EISA. Became obsolete when CPU speeds increasedobsolete when CPU speeds increased

Expansion Card SlotsExpansion Card Slots PCI – Peripheral Component InterconnectPCI – Peripheral Component Interconnect. .

Provides a high speed bus structure needed for Provides a high speed bus structure needed for faster CPU’s. Original PCI bus speed was 33Mhz. faster CPU’s. Original PCI bus speed was 33Mhz. It has now evolved to bus speeds around 533Mhz.It has now evolved to bus speeds around 533Mhz.

AGP – Accelerated Graphics PortAGP – Accelerated Graphics Port. Designed . Designed exclusively for video cards, especially 3-D graphic exclusively for video cards, especially 3-D graphic support. Is as close as possible to the CPU and support. Is as close as possible to the CPU and RAM to allow higher data transfer rates. RAM to allow higher data transfer rates.

Data PortsData Ports Serial PortsSerial Ports – connects to devices that transfer data – connects to devices that transfer data

one bit at a time over one electrical conductor. one bit at a time over one electrical conductor. There is one conductor for transmit and one for There is one conductor for transmit and one for receivereceive

Parallel PortParallel Port – Introduced as a high speed data – Introduced as a high speed data transfer port. Has changed quite a bit since. transfer port. Has changed quite a bit since. Transmits 8 bits simultaneously over 8 electrical Transmits 8 bits simultaneously over 8 electrical conductors.conductors. Common parallel port devices are printers, scanners Common parallel port devices are printers, scanners

and faxesand faxes Used to be unidirectional only (data out only)Used to be unidirectional only (data out only) Extended Capabilities Port (ECP) allowed bidirectional Extended Capabilities Port (ECP) allowed bidirectional

parallel data transfer (data in and out)parallel data transfer (data in and out) USBUSB – Universal Serial Bus, was designed to replace – Universal Serial Bus, was designed to replace

the existing variety of ports and expansion slots. The the existing variety of ports and expansion slots. The USB 2.0 can achieve data rates as high as 480Mbps. USB 2.0 can achieve data rates as high as 480Mbps. Carries data and commands on two twisted data Carries data and commands on two twisted data lineslines

Data PortsData Ports

USB USB PortsPortsSerial Serial

PortPortVideo Video PortPort

Audio Audio PortsPorts

Parallel Parallel PortPort

LAN PortLAN PortMouse and Mouse and Keyboard Keyboard

PortsPorts

IEEE IEEE 1394 Port1394 Port

System ResourcesSystem Resources System resources are resources that must be System resources are resources that must be

assigned and made available for devices such as assigned and made available for devices such as printers, modems, disk drives, a mouse, sound printers, modems, disk drives, a mouse, sound card, etc.card, etc.

The major system resources to consider are . . . . The major system resources to consider are . . . . I.O port addressI.O port address Memory addressesMemory addresses IRQ’sIRQ’s DMA settingsDMA settings

Memory Address Range is an assigned section Memory Address Range is an assigned section of memory used as a temporary storage area of memory used as a temporary storage area for data before it is transferredfor data before it is transferred

I/O Port Address is assigned to a device for I/O Port Address is assigned to a device for identification, for communication purposesidentification, for communication purposes

Both are expressed as a range, and in Both are expressed as a range, and in hexadecimal notation (i.e. 02E8h – 02EFh)hexadecimal notation (i.e. 02E8h – 02EFh)

System ResourcesSystem Resources IRQ SettingsIRQ Settings

Devices connected to a computer motherboard need the Devices connected to a computer motherboard need the attention of the CPUattention of the CPU

The only way is through an orderly system of IRQ The only way is through an orderly system of IRQ settingssettings

IRQ stands for Interrupt RequestIRQ stands for Interrupt Request An IRQ literally interrupts the processes taking place in An IRQ literally interrupts the processes taking place in

the CPU and requests that the processor pay attention the CPU and requests that the processor pay attention to a specific deviceto a specific device

Types of interrupts . . . .Types of interrupts . . . . Hardware - Interrupts physically wired to the computer Hardware - Interrupts physically wired to the computer

busbus Software – Interrupts programmed into the software that Software – Interrupts programmed into the software that

call for the CPU’s attentioncall for the CPU’s attention IRQ’s are prioritized. The lower the number, the higher IRQ’s are prioritized. The lower the number, the higher

the prioritythe priority IRQ 0 is the system timer. It has the highest priority IRQ 0 is the system timer. It has the highest priority

because it is responsible for the timing of all devices, because it is responsible for the timing of all devices, including the CPUincluding the CPU

System ResourcesSystem Resources DMA ChannelsDMA Channels

In early computers, the CPU controlled all devices In early computers, the CPU controlled all devices and their functions. For example, when data is and their functions. For example, when data is moved from floppy drive to RAM, each data bit would moved from floppy drive to RAM, each data bit would have to be transferred to the CPU, then from the have to be transferred to the CPU, then from the CPU to the RAM.CPU to the RAM.

DMA allows the floppy disk to transfer all the data DMA allows the floppy disk to transfer all the data directly to the RAM without the involvement of the directly to the RAM without the involvement of the CPUCPU

DMA stands for Direct Memory AccessDMA stands for Direct Memory Access A combination of hardware and software that allows A combination of hardware and software that allows

certain system devices direct access to the memory. certain system devices direct access to the memory. This speeds up the process by not bothering the CPU This speeds up the process by not bothering the CPU (bottlenecking).(bottlenecking).

A DMA controller has 4 channels each, with two A DMA controller has 4 channels each, with two controllers per motherboard.controllers per motherboard.

Chip SetsChip Sets Earlier PC’s had may more individual components Earlier PC’s had may more individual components

mounted on the motherboardmounted on the motherboard They were eventually redesigned into units called They were eventually redesigned into units called

chipsetschipsets Chipset – a name for the collection of electronic Chipset – a name for the collection of electronic

circuitry required to carry out certain common circuitry required to carry out certain common motherboard functionsmotherboard functions Communication between PCI and ISA busCommunication between PCI and ISA bus Controlling DMAControlling DMA Directing IRQ’sDirecting IRQ’s Serve as temporary memoryServe as temporary memory

Commonly divided into two categories . . . .Commonly divided into two categories . . . . North Bridge – used to transfer and control higher North Bridge – used to transfer and control higher

data speed systems such as graphics and DVD data speed systems such as graphics and DVD hardwarehardware

South Bridge – used to control the slower devices South Bridge – used to control the slower devices associated with the PCI and ISA busesassociated with the PCI and ISA buses

Plug and PlayPlug and Play PnP is the automatic assignment of system PnP is the automatic assignment of system

resources such as DMA channels, interrupts, resources such as DMA channels, interrupts, memory and port assignmentsmemory and port assignments

Simply plug in a device and the system software Simply plug in a device and the system software automatically assigns the system resourcesautomatically assigns the system resources

To work properly, BIOS, hardware being installed, To work properly, BIOS, hardware being installed, and the operating system must all support PnP and the operating system must all support PnP technologytechnology

In the past, physical jumpers and/or DIP switches In the past, physical jumpers and/or DIP switches had to be set on the hardware to identify IRQ had to be set on the hardware to identify IRQ settings and port addressessettings and port addresses

Windows 95 and beyond support PnP to different Windows 95 and beyond support PnP to different degrees, depending on the version and device degrees, depending on the version and device drivers availabledrivers available

BIOS and CMOSBIOS and CMOS BIOS – a read only memory (ROM) chip that contains a BIOS – a read only memory (ROM) chip that contains a

group of software programs written in machine group of software programs written in machine languagelanguage

Machine languageMachine language is a language that uses hexadecimal is a language that uses hexadecimal codes to write a programcodes to write a program

BIOS is designed to initiate three different activities:BIOS is designed to initiate three different activities: POST – Power On Self TestPOST – Power On Self Test CMOS setup program (BIOS setup)CMOS setup program (BIOS setup) Communications between the system hardware and Communications between the system hardware and

operating systemoperating system BIOS controls the sequence of boot devicesBIOS controls the sequence of boot devices Upgrading BIOS – modern PC’s use Flash BIOS. It is Upgrading BIOS – modern PC’s use Flash BIOS. It is

an EEPROM which is electrically erased and then an EEPROM which is electrically erased and then reprogrammed using software available through the reprogrammed using software available through the motherboard manufacturer’s Web site and an updated motherboard manufacturer’s Web site and an updated BIOS program fileBIOS program file

CMOS – A battery backed RAM chip that stores the CMOS – A battery backed RAM chip that stores the BIOS setup informationBIOS setup information

POSTPOST Short for Power On Self TestShort for Power On Self Test A simple diagnostic program that is initiated at A simple diagnostic program that is initiated at

system power turn onsystem power turn on It verifies that the major computer components are It verifies that the major computer components are

installed and in working orderinstalled and in working order Typical devices checked are:Typical devices checked are:

CPU, ROM, RAM, keyboard, monitor, mouse, and CPU, ROM, RAM, keyboard, monitor, mouse, and hard drivehard drive

It is not as sophisticated as diagnostic software, but It is not as sophisticated as diagnostic software, but it will check for major problemsit will check for major problems

When finished, usually one “beep” is heard to let When finished, usually one “beep” is heard to let the user know everything is in working orderthe user know everything is in working order

If error is detected, an error code is displayed and If error is detected, an error code is displayed and a series of beeps are heard that match the codea series of beeps are heard that match the code

Error and beep codes can be obtained from the Error and beep codes can be obtained from the manufacturer’s Web sitemanufacturer’s Web site