chapter5 motherboard

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Motherboards

The Main Board on a PC


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Installed Motherboard


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Principal Components

CPU connector BIOS Chipset Data Buses Expansion Slots Keyboard and Mouse connections Video Cache

Ethernet Sound Power connector


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How Motherboards Work

A Motherboard is a multi-layered printed circuit board

Think of a motherboard as a scale model of a futuristiccity with many modular plug-in buildings, each usingpower from a common electrical system.

Multiple-lane highways of various widths transport databetween the buildings.

The motherboard is the data and power infrastructure forthe entire computer.

Various circuit cards performing various functions allplug into many similar sockets on a common circuitboard.


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How Motherboards Work (Circuits)

A motherboard is a multi-layered printed circuitboard

Copper circuit paths called traces that resemble acomplicated roadmap carry signals and voltages

across the motherboard. Layered fabrication techniques are used so that

some layers of a board can carry data for the BIOS,processor and memory buses while other layerscarry voltage and ground returns without the pathsshort-circuiting at intersections.

The insulated layers are manufactured into onecomplete, complex sandwich.

Chips and sockets are soldered onto the

motherboard.
http://computer.howstuffworks.com/bios.htmhttp://computer.howstuffworks.com/microprocessor.htmhttp://computer.howstuffworks.com/computer-memory.htmhttp://computer.howstuffworks.com/computer-memory.htmhttp://computer.howstuffworks.com/microprocessor.htmhttp://computer.howstuffworks.com/bios.htm


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Chipset

Northbridge The North Bridge is so named because it is

the connection between the high-speedprocessor bus (66/100/133/200/266/400MHz)

and the slower AGP (66/133/266/533MHz) andPCI (33/66MHz) busses.

The North Bridge is what the chipset isnamed after, meaning that, for example, what

we call the 440BX chipset is actually derivedfrom the fact that the actual North Bridgechip part number is 82443BX.


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Chipset - Southbridge

The South Bridge is the bridge

between the PCI bus (33/66MHz) andthe even slower ISA bus (8MHz).


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The Super I/O is a separate chip attached tothe ISA bus that is really not considered partof the chipset and often comes from a third

party, such as Winbond, NationalSemiconductor or Standard MicroSystems(SMS).

The Winbond 83977TF Multi I/O supports

IrDA and floppy interfaces, oneSPP/EPP/ECP parallel port and two 16550UART compatible serial ports.


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Traces (Data Paths)


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AMD CPU Connectores

Socket 7 Socket A


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Pentium Socket Connectors


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Form-factors

1. AT

2. ATX

3. Baby-AT

4. LPX


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Typical AT Form-factor Layout

Notice the layout

Connectors are onthe short edge.


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Typical AT Form-factor Layout


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Look for the big hole


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BABY ATor BAT

The Baby AT (BAT) formatreduced the dimensions of themotherboard to a typical 9inwide by 10in long

BAT motherboards are

generally characterised bytheir shape, AT-style keyboard connector

soldered to the board

Serial and parallel portconnectors which are attached

using cables between thephysical ports mounted on thesystem case

corresponding connectorslocated on the motherboard.
http://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=Baby%20AThttp://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=Baby%20AT


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LPX

The LPX format is a specialisedvariant of the Baby-AT used inlow profile desktop systems andis a loose specification with avariety of proprietaryimplementations.

Expansion slots are located on acentral riser card, allowing cardsto be mounted horizontally.

This arrangement can make itdifficult to remove themotherboard, and the morecomplex engineering requiredadds to system costs. As the risercard prevents good airflow withinthe system case, additionalchassis fans are almost always


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ATX

The Intel Advanced/MLmotherboard, launched in1996, was designed to solvethese issues and marked thebeginning of a new era inmotherboard design.

Its size and layout arecompletely different to the BATformat, following a newscheme known as ATX.

The dimensions of a standardATX board are 12in wide by

9.6in long; mini ATX variant is typically of

the order 11.2in by 8.2in.

The ATX design gets roundthe problem by moving theCPU socket and the voltageregulator to the right-hand sideof the expansion bus.

Room is made for the CPU by

making the card slightly wider,and shrinking or integratingcomponents such as the FlashBIOS, I/O logic and keyboardcontroller.

This means the board need

only be half as deep as a fullsize Baby AT, and there's noobstruction whatsoever to thesix expansion slots (two ISA,one ISA/PCI, three PCI).
http://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=ATXhttp://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=I/Ohttp://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=I/Ohttp://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=ATX


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ATX

The ATX uses a new specification of power supply thatcan be powered on or off by a signal from themotherboard.

This allows notebook-style power management andsoftware-controlled shutdown and power-up. A 3.3Voutput is also provided directly from the power supply.

Accessibility of the processor and memory modules isimproved dramatically, and relocation of the peripheralconnectors allows shorter cables to be used.

This also helps reduce electromagnetic interference. TheATX power supply has a side vent that blows air from theoutside directly across the processor and memorymodules, allowing passive heatsinks to be used in mostcases, thereby reducing system noise.


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Typical ATX Form-factor Layout

Notice the layout

Connectors are onthe long edge


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Typical ATX Form-factor Layout


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ATX Back Panel-2 small holes


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ATX power connections


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ATX


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NLX

NLXIntel's NLX design, introduced in1997, is an improvement on theLPX design for low-profilesystems, with an emphasis onease of maintenance.

The NLX format is smaller,typically 8.8in wide by 13in long,so well suited for low-profiledesktop cases.

All expansion slots, power cablesand peripheral connectors arelocated on an edge-mounted risercard, allowing simple removal ofthe main motherboard, which ismounted on rails in the chassis.

It uses a full-width I/O shield toallow for different
http://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=NLXhttp://www.forums.pctechguide.com/restricted/WordFind.php?wordInput=NLX


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MICRO ATX

MicroATXIntroduced in the late1990s, the MicroATX

is basically a smallerversion of Intel's ATXspecification,intended for compact,

low-cost consumersystems with limitedexpansion potential.

The maximum size ofthe board is 9.6insquare, and its

designed to fit intoeither a standard ATXcase or one of thenew micro-tower

desktop designs.


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The double-decker I/Oshield is the same as thaton the ATX design, butthere's only provision for

up to four expansion slotsas opposed to the seventhat ATX allows.

The microATX alsoallows use of a smaller

power supply, such asthe SFX design, which isreduced in both size andpower output.


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FlexATX

FlexATXThe FlexATX is a natural evolutionof the Intel's microATX form factorwhich was first unveiled in late1999.

The FlexATX addendum to themicroATX specification addressesthe requirements of only themotherboard and not the overallsystemsolution

It does not detail the interfaces,memory or graphics technologiesrequired to develop a successfulproduct design.

These are left to the implementerand system designer. The choiceof processor is, however, limitedto socket-only designs.


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FlexATX

The principal difference between FlexATX andmicroATX is that the new form factor reducesthe size of the motherboard - to 9in x 7.5in.

Not only does this result in lower overall system

costs, it also facilitates smaller system designs. The FlexATX form factor is backwards

compatible with both the ATX and micro-ATXspecifications

Use of the same motherboard mounting holesas both of its predecessors avoids the need toretool existing chassis.

The table belo compares the


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The table below compares thedimensions of the microATX, FlexATXand ITX form factors

Form Factor Max. Width (mm) Max. Depth (mm)

microATX 244 244

FlexATX 229 191

ITX 215 191


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Motherboard Connections

1. Power

2. IDE devices

3. Floppy

4. Expansion Slots

5. Front panel

6. USB

7. Miscellaneous8. External Connectors


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IDE Connectors


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IDE Cable End


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IDE Connector Pin 1


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IDE Cable Connected to Motherboard


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Floppy Controller


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Connecting Devices to Motherboard

1. PCI

2. ISA

3. Firewire

4. USB5. AGP

6. IR

7. IDE controllers8. Sound devices


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Hard drive Jumpers


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IDE Device Configuration


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CD\CDR Identification


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CD Connections


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IDE Device Configuration


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Name the parts.


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Power


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Configuring the motherboard

1. Jumpers and Dip Switches

2. Bus Speed

3. CPU speed

4. Multipliers5. Jumperless Motherboards

6. Introduction to BIOS


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Jumpers


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Jumpers and Shunts


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Front Panel


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IDE devices review

1. Master Slave configuration

2. Motherboard IDE controller

3. Pin 1 orientation

4. IDE config in BIOS


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POST Screen


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AGP, PCI, AMR


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Installing the PCI cards


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FIC 2013 Socket 7 ATX Board


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Gigabyte GA-6VX7-4X

CMOS Chip


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CMOS Chip

(Complementary Metal Oxide Semiconductor)

64 Bytes ofInformation

Stores BIOS softwareHas Independent

power source(Battery)

Name Interface Description


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Socket 1 169-pin Found on 486 motherboards, operated at 5 volts and supported 486 chips, plus the DX2, DX4 OverDrive.

Socket 2 238-pin A minor upgrade from Socket 1 that supported all the same chips. Additionally supported a Pentium OverDrive.

Socket 3 237-pin

Operated at 5 volts, but had the added capability of operating at 3.3 volts, switchable with a jumper setting on themotherboard. Supported all of the Socket 2 chips with the addition of the 5x86. Considered the last of the 486sockets.

Socket 4 273-pin

The first socket designed for use with Pentium class processors. Operated at 5 volts and consequently supported onlythe low-end Pentium-60/66 and the OverDrive chip. Beginning with the Pentium-75, Intel moved to the 3.3 volt

operation.

Socket 5 320-pinOperated at 3.3 volts and supported Pentium class chips from 75MHz to 133MHz. Not compatible with later chips

because of their requirement for an additional pin.

Socket 6 235-pinDesigned for use with 486 CPU's, this was an enhanced version of Socket 3 supporting operation at 3.3 volts. Barely

used since it appeared at a time when the 486 was about to be superseded by the Pentium.

Socket 7 32-pinIntroduced for the Pentium MMX, the socket had provision for supplying the split core/IO voltage required by this and

later chips. The interface used for all Pentium clones with a 66MHz bus.

Socket 8 387-pinUsed exclusively by the Intel Pentium Pro, the socket proved extremely expensive to manufacture and was quickly

dropped in favour of a cartridge-based design.

Slot 1 242-way connector The circuit board inside the package had up to 512KB of L1 cache on it - consisting of two 256KB chips - which ran athalf the CPU speed. Used by Intel Pentium II, Pentium III and Celeron CPUs.

Slot 2 330-way connectorSimilar to Slot 1, but with the capacity to hold up to 2MB of L2 cache running at the full CPU speed. Used on Pentium

II/III Xeon CPUs.

Slot A 242-way connectorAMD interface mechanically compatible with Slot 1 but which using a completely different electrical interface. Introduced

with the original Athlon CPU.

Socket 370 370-pinBegan to replace Slot 1 on the Celeron range from early 1999. Also used by Pentium III Coppermine and Tualatin CPUs

in variants known as FC-PGA and FC-PGA2 respectively.

Socket A 462-pinAMD interface introduced with the first Athlon processors (Thunderbird) with on-die L2 cache. Subsequently adopted

throughout AMD's CPU range.

Socket 423 423-pinIntroduced to accommodate the additional pins required for the Pentium 4's completely new FSB. Includes an Integral

Heat Spreader, which both protects the die and provides a surface to which large heat sinks can be attached.

Socket 603 603-pin

The connector for Pentium 4 Xeon CPUs. The additional pins are for providing more power to future CPUs with largeon-die (or even off-die) L3 caches, and possibly for accommodating inter-processor-communication signals forsystems with multiple CPUs.

Socket 478 478-pin

Introduced in anticipation of the introduction of the 0.13-micron Pentium 4 Northwood CPU at the beginning of 2002. It'smicro Pin Grid Array (PGA) interface allows both the size of the CPU itself and the space occupied by thesocket on the motherboard to be significantly reduced.


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Comprando Un Motherbaord


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chapter5 motherboard

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