The document discusses the motherboard and its components. It describes how the motherboard is the main circuit board that contains the CPU and connects all internal components. It then discusses the different types of motherboards that have evolved over time from XT to ATX. Finally, it provides details on the key components found on motherboards such as the CPU socket, memory slots, BIOS, chipset and expansion slots.

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1. Motherboard
A motherboard is the main printed circuit board in a computer that contains the central
processing unit, appropriate coprocessor and support chips, device controllers, memory,
and also expansion slots to give access to the computer’s internal bus. The motherboard is
the PCs centre of activity. All devices in a computer are in some way connected to the
motherboard.
The motherboard is mounted inside the case, opposite the most easily accessible side. It is
securely attached via small screws through pre-drilled holes. The front of the
motherboard contains ports that all of the internal components connect to. A single socket
/slot houses the CPU. Multiple slots allow for one or more memory modules to be
attached. Other ports reside on the motherboard, which allow the floppy drive, hard drive
and optical drive to connect via ribbon cables. Small wires from the front of the computer
case connect to the motherboard to allow the power, reset and LED lights to function.
Power from the power supply is delivered to the motherboard by use of a specially
designed port[2].
Fig 1.Motherboard [1]

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2.Types of Motherboard
2.1 XT Motherboard
XT Stands for eXtended Technology. These are all old model motherboard. In
thismotherboard, we find old model processor socket LIF (Low Insertion Force) sockets;
ram slots Dimms and ISA (Industry Standards Architecture) slots, 12pin Power Connector
and no ports.They have slot type processors, Dimms memory modules, ISA slots for add-
on card, and no ports. There are connectors and add-on cards for ports[3].
Eg: Pentium-I, Pentium-MMX, Pentium -II and Pentium-II Processors.
Fig.2 XT Motherboard[3]
2.2 AT Motherboard
AT stands for Advanced Technology. Advanced Technology Motherboards have PGA (Pin
Grid Array) Socket, SD Ram slots, 20pin power connector PCI slots and ISA slots. We
find the above components on AT motherboards[3].
Eg: Pentium-III Processors
Fig.3 AT Motherboard [3]

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2.3 Baby AT Motherboard
Baby AT Motherboards have the combination of XT and AT. They have both slot type
processor sockets and PGA processor sockets, SD Ram slots and DDR Ram slots, PCI
slots and ISA slots, 12 Pin power connector and 20Pin power connector and Ports [3]
.
Eg: Pentium-III and Pentium-IV
Fig.4 Baby AT Motherboard[3]
2.4 ATX Motherboard
ATX stands for Advanced Technology eXtended.Latest motherboards all are called as
ATX motherboards. Designed by ATX form factor in this motherboard, we find MPGA
Processor Sockets, DDR Ram slots, PCI slots, AGP slots, Primary and secondary IDE
interfaces, SATA connectors, 20pin and 24 pin ATX power connector and Ports [3]
.
Eg: Pentium-IV, Dual Core, Core 2 Duo, Quad Core, i3, i5 and i7 Processors.
Fig.5 ATX Motherboard [3]

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3. Motherboard Components
Below is a listing of links that describe each of the above mentioned motherboard
components in additional detail [1]
.
 Clock Generator
 CPU socket
 Memory Socket
 ROM Bios
 CMOS Ram
 Battery
 Chipset
 Expansion Slot
 AGP Port
 IDE Ports
 Floppy Disk port
 IO Connectors/USB ports
 Main Power Connector
 Front Panel Connecting
3.1Clock Generator
Clock generator on the mother board will generate the clock signal called System clock
Bus or, Front clock Bus.
Fig.6 Clock Generator[1]

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Front side bus clock will be multiplied by the multiplying Front side bus clock will be
multiplied by the multiplying circuit to make frequency high enough to reach the core
clock frequency of the CPU.
For example if the front side bus is 100Mhz and the core, clock of the CPU is 1.1Ghz the
front side bus must be multiplied by 11 ( 100 x 11 = 1100Mhz or 1.1Ghz ) [1]
.
3.2 CPU Socket
There are 3 type of CPU Socket that are currently popular in the market,
1. Socket 478 this socket is for CPU Pentium 4 and
2. Socket 370 this socket is for CPU Pentium III, Celeron II and Cyrix C3,
3. Socket A or called socket 462, this socket is for CPU AMD Athlon and Duron.
All of the 3 type of socket are ZIF (zero insert force) socket the CPU can be inserted
in to the socket without having to be forced [1]
.
Fig.7 CPU Socket[1]
3.3 Memory Socket
A memory slot, memory socket, or RAM slot is what allows computer memory (RAM) to
be inserted into the computer. Depending on the motherboard, there will usually be 2 to 4
memory slots (sometimes more on high-end motherboards) and are what determine the
type of RAM used with the computer. The most common types of RAM are SDRAM and
DDR for desktop computers and SODIMM for laptop computers, each having various

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types and speeds. In the below picture, is an example of what memory slots may look like
inside a desktop computer. In this picture, there are three open available slots for three
memory sticks [15].
Fig. 8 Memory Socket [1]
3.4 ROM Bios
BIOS ( Basic Input Output System ) BIOS is a program that work as a part of the
hardware, the program is stored in the read only memory ( ROM ) ROM can retain
BIOSpermanently even though electric power was removed fromthe system[1]
.
Fig.9 ROM Bios[1]
3.5 CMOS Ram
CMOS (complementary metal-oxide semiconductor) RAM is a type of memory chip that
has low power requirements. When in a PC, it operates by using a series of small

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batteries. These batteries allow for the CMOS RAM, on its tiny 64-bye region, to retain
data even when the PC has[5]
Fig.10 CMOS Ram[6]
3.6 Battery
This is a 3 volt battery, this battery supplies the power to CMOS ram for CMOS ram to
retain the information during system powered off, the battery may be last for 5 or 6
years[1]
Fig.11 Battery[1]
When the battery is weak the PC will show and inaccurate time of day clock, or show
CMOS check sum error message during boot, at this time the user defined information in
the CMOS ram may be lost, the PC may be still able to run by the default value in BIOS
that was defined by manufacturer [1]
.

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3.7 Chipset
Fig.12 Chipset [1]
Chip set is a set of IC, used to be many IC’s work together to provide support to CPU and
I/O ( input out device ) and make the whole system Mother Board Component works,
currently the chipset are integrated in to very few large scale IC[1]
.
3.8 Expansion Slot
An expansion slot is a slot located inside a computer on the motherboard that allows
additional boards to be connected [1]
.
Fig.13 Expansion Slot [7]
Eg.
 AGP - Video card
 AMR - Modem, Sound card
 CNR - Modem, Network card, Sound card
 EISA - SCSI, Network card, Video card

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 ISA - Network card, Sound card, Video card
 PCI - Network card, SCSI, Sound card, Video card
3.9 AGP Port
AGP (Accelerated Graphic Port)port is a high speed data transfer port, this port is used by
the display adapter card that demands so much data with in short period of time [1]
.
Fig.14 AGP Port[1]
3.10 IDE Ports
Fig.15 IDE Ports[1]
IDE ports, the 40 pin connector, these ports are for connecting hard disk drives[1]
.
3.11Floppy Disk port
Floppy disk port is a 34 pin connector use 34 wires cable, the normal cable will have 2

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connectors 2 floppy drives can be connected, one drive at the end of the cable is drive A
the other drive is at the middle of the cable and is drive B[1]
.
Fig.16 Floppy Disk port[1]
3.12IO Connectors/USB ports
USB Universal Serial Bus, the data is serially transferred on this port between USB
device and USB controller by using 2 wires.USB port has just newly implement with in
CPU Pentium's time, in the time of CPU 8046 USB port is not yet in placed[1]
.
Fig.17 IO Connectors/USB ports[1]

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Fig.18 Serial and parallel Port[4]
.
3.13 Main Power Connector
Power supply connector from power supply will easily insert into the mother board
connector, if you find it is hard to insert this mean the connector is in the wrong
direction[1]
.
Fig.19 Main Power Connector[1]

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3.14 Front Panel Connecting
The pin lay out show here is a guide line and explanation of the meaning, difference
mother board the pin lay out can be difference[1]
.
 HD+, HD- to connect to the hard disk indicator at front of the PC, when hard disk is
working the HDD indicator at the front of the case will blink.
 Power Led +, Power Led- to connect to the power on indicator at the front of the PC
when the PC is powered on the indicator will turns on.
 MSG +, MSG - to connect to the Led indicator at the front of the PC, this light will
turns on when the PC is in standby mode.
 Power +, Power - to connect to the power on/off switch at the front of the PC.
 RES+, RES- to connect to the Reset switch from the frontof the PC.
4. Other Motherboard Components
Few more components of Motherboard are given below[4]
.
 BIOS
 Bus
 Cache memory
 Chipset
 Diode
 Dip switches
 Electrolytic
 Fuse
 Game port and MIDI header
 Internal speaker
 Keyboard controller
 LCC (Leadless Chip Carrier)
 Network header
 Obsolete expansion slots (AMR, CNR, EISA, ISA, VESA)
 Obsolete memory slots (SIMM- SingleIn-line Memory Module)
 Onboard LED (Light Emitting Diode)

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 Parallel port header
 PS/2 header
 Resistor
 RTC (Real Time Clock)
 Serial port header
 Screw hole aka mounting hole
 SCSI (Small Computer System Interface)
 Solenoid
 Voltage regulator
5.Booting Process
5.1Booting Process
Booting is a bootstrapping process that starts operating systems when the user turns on a
computer system. The boot loader typically loads the main operating system for the
computer[10]
.
5.1.1 Booting
Booting is a process or set of operations that loads and hence starts the operating system,
starting from the point when user switches on the power button[9]
.
5.1.2 Booting Sequence
Basically documents related to booting are generally confusing as they are often related to
some specific operating system that is Linux machine or Windows machine. But I will
keep it as general as possible.General Booting sequence comprises of the following
steps[9]
.
Turn on the Power button.
 CPU pins are reset and registers are set to specific value.
 CPU jump to address of BIOS (0xFFFF0).
 BIOS run POST (Power-On Self Test) and other necessary checks.
 BIOS jumps to MBR (Master Boot Record).
 Primary Boot loader runs from MBR and jumps to Secondary Boot loader.

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 Secondary Boot loaders load Operating System.
As soon as we turn the power button, the reset signal is sent and the registers in the CPU
are set to their predefined value. The first and foremost is the reset vector as shown in the
figure. It should be noted that RAM contains the garbage value at this time, and the
instructions/data stored at any memory location is due to the memory map of the chipset.
Memory map maps the location (address) to flash memory containing values or
instructions. It is ensured that the instruction stored at this reset vector location is jump to
system BIOS, as BIOS takes up further process of powering up the system[2]
.
Fig.20Booting Sequence[9]
5.2 BIOS-Basic Input Output System
Power up CPU is reset and its registers are set to the default value, which is an address
pointing or directing to the hardware containing BIOS. Generally the hardware is
EEPROM containing the BIOS.
The tasks performed by BIOS are categorized as follows[9]
.

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POST- Power on Self Test is the foremost routine which checks and tests the basic
hardware. If it fails then it displays error. Initialization of the hardware devices by letting
them runs their individual BIOS[9]
.
5.3Boot Sector
A sector is a part of the hard disk having length of 512 bytes. A sector is termed as boot
sector because of its location and because this sector is responsible for the furtherboot
process of the system.
Fig.21Boot Sector[8]
This boot sector is generally called Master Boot Record. The MBR is a 512-byte sector,
which is located in the first sector on the disk (sector 1 of cylinder 0, head 0). As soon as
BIOS gets the boot sector, it tends to copy MBR to RAM and switches the execution
authority to it[9]
.
In the MBR the first 446 bytes are the primary boot loader, which is also referred to
asPBL.The next sixty-four bytes are the partition table, which has the record for each of
the partitions[1]
.

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Conclusion
This report gives what is Booting Process? Means Booting is a process or set of
operations that loads and hence starts the operating system, starting from the point when
user switches on the power button, How computer Boots up?, Motherboard Means main
circuit board of your computers and have many components.

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References
1. www.oocities.org/inhs_iloilo/References/motherboard.pdf
2. http://www.scribd.com/doc/28965773/Motherboard-Project motherboard
3. http://hardwareclasses.blogspot.in/2012/07/motherboard-types-and-differences.html
types
4. http://www.computerhope.com/jargon/m/mothboar.htm
5. http://www.tech-faq.com/cmos-ram.html
6. www.microdesignsinc.com
7. http://www.computerhope.com/jargon/e/expaslot.htm expansion
8. www.karbosguide.com boot sector
9. http://www.engineersgarage.com/tutorials/how-computer-pc-boots-up
10. http://in.answers.yahoo.com/question/index?qid=20090321073607AAxvrKi