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Unit 2: Motherboard
Prepared by : Mohd Zuhaimi b Zolkifli
E5164 COMPUTER SYSTEM DIAGNOSIS AND MAINTENANCE
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Motherboard?
The Motherboard is the main chassis of
the PC.
All data that flows from component tocomponent inside the computer at some
point goes through the motherboard.
That is the Motherboards main function to
direct data flow to the right components.
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Function of motherboard maincomponents
BIOS & CMOS
Sockets
Ports
CPU
Expansion Slot
Buses
Chipset
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CPU?
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CPU Central Processing Unit
The brain of computer
The portion of a computer system that
carries out the instructions of a computer
program.
Does all the calculations and performs
90% of all the functions of a computer.
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Processor Socket/Slot (1)
Sockets are basically flat and have several rows
of holes arranged in a square.
Processor slot is another method of connectingprocessor on the motherboard but one which
an Intel Pentium II or Pentium III-class processor
on a special expansion card can be inserted.
More complex processor (Intel Itanium) use a
package known as a pin array cartridge (PAC).
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Processor Socket/Slot (2)
CPU SOCKET
SLOT 1 CONNECTOR
SLOT
PAC SOCKET
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Type of Expansion Slot (1)
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Type of Expansion Slot (2)
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Related Buses
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What is bus?The paths the computer usesThe paths the computer uses
to transport data from one component toto transport data from one component to
another.another. (It doesn't matter how fast your CPU is or your diskdrive if the bus isn't wide and fast.)
Fast and wide?TheThe widthwidth of the bus isof the bus is
determined by how many bits of data thedetermined by how many bits of data the
bus can transfer in one operation.bus can transfer in one operation.(Therefore, a
32-bit bus is wider than a 16-bit bus.)TheThe speedspeed of aof a
bus is rated in megahertz (MHz), which isbus is rated in megahertz (MHz), which isone million cycles per second.one million cycles per second. (A single hertz isone electronic cycle that performs one operation.)
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Difference between computer
buses
Data width
Cycle rate
To determine the bandwidth, or
the total amount of data that the
bus can transmit.
Device
Management
The maximum number of
supported devices and the
difficulty of configuring them.
TypeTwo types of buscommunications, serial and
parallel.
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Front Side Bus - FSB
The FSB is the interface between the CPU and themotherboard, specifically the North Bridge/MemoryController Hub.
Also connects the various hardware components tothe main microprocessor, or central processing unit(CPU).
The FSB is bi-directional, meaning data can flow both
ways, allowing components to send and receive datafrom the CPU.
Speed of FSB is depends on how wide the front sidebus is, its frequency, and the amount of data it can
process per clock tick of the CPU
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FSB - Example
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Memory Bus The memory bus is the interface between
the RAM and the motherboard
The memory bus is made up of two parts:the data bus and the address bus
Data Bus: which carries actual memory datawithin the PC
Address Bus: used to select the memoryaddress that the data will come from or go toon a read or write
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Input/Output Buses (1)
I/O buses connect the CPU to all othercomponents, except RAM.
On modern PCs, usually they are fourbuses: ISA bus, which is an old low speed bus, soon to be
excluded from the PC design.
PCI bus, which is a new high speed bus.
USB bus (Universal Serial Bus), which is a newlow speed bus. AGP bus, which solely is used for the graphics card.
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Input/Output Buses (2)
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Chipset
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Whats a chipset?A collection of chips orA collection of chips orcircuits that perform interface andcircuits that perform interface and
peripheral functions for the processorperipheral functions for the processor.
Collection?Usually the circuitry thatUsually the circuitry thatprovides interfaces for memory, expansionprovides interfaces for memory, expansion
cards, onboard peripherals and generallycards, onboard peripherals and generallydictates how a motherboard will talk to thedictates how a motherboard will talk to theinstalled peripherals.installed peripherals.
- Functions of chipset can be divided into- Functions of chipset can be divided intotwo major functional groups :two major functional groups : NorthbridgeNorthbridgeandandSouthbridgeSouthbridge..
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Northbridge
Management of high-speed peripheral
communications.
Responsible forcommunications with
integrated video using AGP and PCIe, and
processor-to-memory communications.
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Southbridge
Responsible forproviding supportto themyriad onboard peripheral (PS/2, Parallel,IDE etc), managing theircommunications
with the rest of the computerand theresource given to them.
Also responsible for managingcommunications with the other expansionbuses (PCI, USB and legacy buses).
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Basic Input/Output System (BIOS)
Chip
Special memory chip contains the BIOS software that
tells the processor how to interact with the rest of the
hardware in the computer.
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CMOS(1)
PC has to keep certain setting when its turned offsuch as:
Date
Time
Hard Drive Configuration
Memory
PC keeps these settings in a special memory chipcalled the Complimentary Metal Oxide
Semiconductor (CMOS) chip.
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CMOS(2)
To keep it setting, the memory must have
power constantly.
Motherboard manufacturers include a
small battery called CMOS Battery to
power the CMOS memory.
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Socket (1)
IDE Socket
Usually use to
connect hard
drive, CD-RW,DVD etc. JTAG IDE Socket
IDE Connector
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Socket (2)
SIMM Socket
holds a single
SIMM
SIMM (single in-
line memory
module )
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Socket (3)
DIMM Socket
Usually use for
DRAM, SDRAM,
non-standard DRAM
module etc
DIMM - Dual in-line
memory module,
comprises a series of
dynamic random
access memory
integrated circuits
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Socket (4)
FDD Socket
used for floppy disk
drives.
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Port (1)
USB Port
the easiest and
most common
technique forconnecting
hardware
simply plug thehardware into your
computer.
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Port (2)
iLink/IEEE1394/FireWire
the highest-
performance
hardware connection
used for digital video
cameras and
external hard disks Most new computers
include at least one
iLink port
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Port (3)
PC Card
to support extremely small accessories, such as wireless adapters
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Port (4)
PS/2
the standard
connection for your
keyboard andmouse.
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Port (5)
Serial or parallel
ports
the oldest
connection type forexternal hardware
accessories
are easy to connect software configures
these connections
automatically
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Main Memory
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Introduction
Also known as RAM(Random Access Memory)
Needs to have electrical power in order to
maintain its information (When power is lost, theinformation is lost too!)
It can be directly accessed by the CPU
Main memory is expensive compared to
external memory so it has limited capacity
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How it work?
A memory chip is an integrated circuit(IC) made of millions of transistors andcapacitors.
A transistor and a capacitor are paired tocreate a memory cell, which represents asingle bit of data. (in DRAM)
The capacitor holds the bit of information. The transistor acts as a switch that lets thecontrol circuitry on the memory chip readthe capacitor or change its state.
A capacitor is like a small bucket-
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pthat is able to store electrons.
To store a 1 in the memory cell,
the bucket is filled with electrons.To store a 0, it is emptied.
The problem with the capacitor'sbucket is that it has a leak.
The memory controllerhas tocome along and recharge all ofthe capacitors holding a 1 beforethey discharge.
The memory controller reads thememory and then writes it rightback.
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Memory Organisation
Magnetictapes
Magneticdisks
I/Oprocessor
CPU
Mainmemory
Cachememory
Auxiliary memory
Register
Cache
Main Memory
Magnetic Disk
Magnetic Tape
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Memory Signals
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NOTE
Each motherboard supports memory
based on the speed of the front side bus
(FSB) and the memorys form factor.
Example: if FSB rated at max speed
533MHz and memory rated at 300MHz,
the memory will operate at only 300Mhz.
(make the computer operate slower thanwhat it could)
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Memory Packaging
The memory slots on the motherboard are
designed for particular module form
factors or styles.
DIP, SIMM and SIPP are obsolete
memory packages.
The most popular form factors for primary
memory modules today are DIMM, RIMM,SoDIMM and MicroDIMM
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Memory Module SIMM (1)
Single in-line memory module containing random access memory used in
computers from the early 1980s to the late 1990s
DRAM technologies used in SIMMs include EDOand FPM.
The first variant of SIMMs has 30 pins and provides9 bits of data.
The second variant of SIMMs has 72 pins andprovides 32 bits of data (36 bits in parity versions)
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Memory Module SIMM (2)
30 pinsSize: 256 KB, 1 MB, 4 MB,
16 MB
Have 12 address lines,
which can provide a total of
24 address bits.
With an 8 bit data width, this
leads to an absolute
maximum capacity of 16
MiB.72 pinsStandard sizes: 1 MiB, 2 MiB, 4 MiB, 8 MiB, 16 MiB,
32 MiB, 64 MiB, 128 MiB
With 12 address lines, which can provide a total of
24 address bits, two ranks of chips, and 32 bit data
output, the absolute maximum capacity is 227 = 128
MiB.
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Memory Module DIMM (1)
Dual In-line Memory Module
comprises a series of dynamic random
access memory integrated circuits.
64-bit memory modules that are used as a
package for the SDRAM family (SDRAM,
DDR and DDR2.
DIMM differentiate the functionality of the
pins on one side of the module from the
corresponding pins on the other side.
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Memory Module DIMM (2)
168-pin SDRAM module
184-pin DDR SDRAM module
DIMM slots
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Memory Module DIMM (3)
DIMM range in capacity from 8 MB to 1
GB per module and can be installed singly
instead of in pairs.
Another standard, Rambus in-line
memory module (RIMM), is comparable
in size and pin configuration to DIMM but
uses a special memory bus to greatlyincrease speed.
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Memory Module SODIMM (1)
Many brands of notebook computers useproprietary memory modules, but severalmanufacturers use RAM based on the smalloutline dual in-line memory module
(SODIMM) configuration. SODIMM cards are small, about 2 x 1 inch (5 x
2.5 cm), and have 144 or 200 pins.
Capacity ranges from 16 MB to 1 GB permodule.
Sub-notebook computers use even smallerDIMMs, known as MicroDIMMs, which have
either 144 pins or 172 pins.
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Memory Module SODIMM (2)
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Type Of Memory (DRAM)
Dynamic random access memory
Has memory cells with a paired
transistor and capacitorrequiringconstant refreshing.
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Type Of Memory (SRAM)
Static random access memory
Uses multiple transistors, typically four to
six, for each memory cell but doesn't have
a capacitor in each cell. It is used primarily
for cache.
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Type Of Memory (FPM DRAM)
Fast page mode dynamic random
access memory
It waits through the entire process of
locating a bit of data by column and row.
Then reading the bit before it starts on the
next bit.
Maximum transfer rate to L2 cache is
approximately 176 MBps.
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Type Of Memory (VideoRAM)
A type of RAM used specifically for videoadapters or 3D accelerators.
VRAM normally has two independent accessports allowing the CPU and graphics processorto access the RAM simultaneously.
VRAM is located on the graphics card andcomes in a variety of formats.
The amount of VRAM is a determining factor inthe resolution and color depth of the display.
VRAM is also used to hold graphics-specificinformation such as 3-D geometry data and
texture maps.
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Type Of Memory (EDO DRAM)
Extended data-out dynamic randomaccess memory
Does not wait for all of the processing of
the first bit before continuing to the nextone.
As soon as the address of the first bit is
located, EDO DRAM begins looking forthe next bit.
It is about five percent faster than FPM.Maximum transfer rate to L2 cache is
approximately 264 MBps.
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Type Of Memory (SDRAM)
Synchronous dynamic random accessmemory
Takes advantage of the burst mode concept togreatly improve performance.
It does this by staying on the row containing therequested bit and moving rapidly through thecolumns, reading each bit as it goes.
The idea is that most of the time the data
needed by the CPU will be in sequence. SDRAM is about five percent faster than EDO
RAM and is the most common form in desktopstoday. Maximum transfer rate to L2 cache is
approximately 528 MBps.
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Memory bank system
H l d t
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How memory load onto
motherboard
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Operating System and Boot
Processes
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Introduction
OS provides aconsistentenvironment forother software toexecute commands.
Gives users aninterface with thecomputer so theycan send commands(input) and receivefeedback or result(output)
OS
Processor
Devices
Hard disks Memory
Input/Output
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OS Terms and Concept
Version normally described by anumber, which tells you how new theproduct is in relation to other versions ofthe product.
Source actual code that defines how apiece of software work. (open source:can modify/ close source: can't modify)
Shell a program that runs on top of theOS and allows the user to issuecommands through a set of menus orsome other graphical interface.
Graphical User Interface (GUI) a method
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Graphical User Interface (GUI) a method
by which a person communicates with a
computer. Network any group of computer that have a
communication link between them.
Cooperative Multitasking a multitaskingmethod that depends on the application itself
to be responsible for using and then freeing
access to the processor.
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Preemptive Multitasking a multitasking
method in which OS allots each
application a certain amount of processortime and then forcibly takes back control
and gives another application or task
access to the processor. Multithreading ability of a single
application to have multiple requests in to
the processor at one time.
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Microsoft Windows
Microsoft Windows was born out of the
Microsoft Disk Operating Systems (MS-
DOS)
The limitations of the DOS command-lineinterface became apparent.
Solution make the OS easier to
navigate, more uniform, and user friendly.
1985 1st version of Windows was
released.
Wi d 1
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Windows 1
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Window 1 - 1985
Featured the tiling window, mouse
support, and menu systems.
Also offered cooperative multitasking,
meaning that more than one Windowsapplication could run concurrently.
It didnt use icons.
More graphical version of the
DOSSHELL.exe program.
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Windows 2
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Windows 2.0 - 1987
Added icons and allowed application
windows to overlap each other, as well as
tile.
Support was also added for PIFs (programinformation files), which allowed the user
to configures Windows to run their DOS
applications more efficiently.
Wi d 3
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Windows 3.x
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Windows 3.x 1990an
A far more flexible memory model (morethan 640kb normally imposed by DOS)
The addition of the File Manager and
Program Manager
Allowed for network support.
Could operate in 386 Enhanced mode
(used part of the hard drive as virtual memory able to use disk memory to supplement the RAM
in the machine.)
Version 3 1(1992) provide better
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Version 3.1(1992) provide better
graphical display capability and multimedia
support, improved Windows error-protection system and let application work
together easily (object linking and embedding OLE)
Version 3.11 (Windows for Workgroup) support both 16-bit and 32-bit application.
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Windows 95
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Windows 95 - 1995
Integrated the OS and the shell.
Designed to be hybrid of the features of
previous DOS versions and newer 32-bit
systems.
Support both 32-bit and 16-bit driver as
well as DOS driver.
Support for Plug and Play (PnP) standard.
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Windows 98/Me/NT/2000/XP
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Other OS
Windows Server 2003 Windows Vista
MAC OS
Linux
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Supplying Power
The internal power supply turns on andinitializes.
The power supply takes some time until it can
generate reliable power for the rest of thecomputer, and having it turn on prematurelycould potentially lead to damage.
Therefore, the chipset will generate a reset
signal to the processor until it receives thePower Good signal from the power supply.
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Bootstrap
A technique which a simple computer programactivates a more complicated system of
programs.
Example: In the start up process of a computersystem, a small program such as BIOS,
initializes and tests that hardware, peripherals
and external memory devices are connected,
then loads a program from one of them andpasses control to it, thus allowing the loading of
larger programs, such as an operating system.
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Power-on self-test (POST)
It is the first step of the more general
process called initial program load (IPL),
booting, or bootstrapping.
On power up, the main duties of POSTare handled by the BIOS, which may hand
some of these duties to other programs
designed to initialize very specificperipheral devices, notably for video and
SCSI initialization.
Principal duties of the main BIOS
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Principal duties of the main BIOS
during POST
Verify the integrity of the BIOS code itself Find, size, and verify system main memory
Discover, initialize, and catalog all system busesand devices
Pass control to other specialized BIOSes (if andwhen required)
Provide a user interface for system'sconfiguration
Identify, organize, and select which devices areavailable for booting
Construct whatever system environment that isrequired by the target OS
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1st stage of typical POST
2nd stage of a POST
Boot Process of DOS Operating
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Boot Process of DOS Operating
System
1. Once the computer system is turned on,the BIOS performs a series of activitiescalled POST that checks to see whether
the peripherals in the system are inperfect order.
2. This Pre Boot Sequence consists of a
series of steps that starts with theexecution of software stored in the ROMcalled firmware.
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5 If the bootable disk is not the floppy the
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5. If the bootable disk is not the floppy, the
MBR finds and searches the partition
table to load and scan all the extendedpartitions to find the primary partition.
6. When it finds one, it implies that it is the
bootable partition, and, the OperatingSystem loader (bootstrap loader) is
loaded from that partition onto the
memory.7. A boot strap loader is a special program
that is present in the boot sector of the
bootable drive
8. MS DOS Operating system comprises of the following files: ---
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IO.SysMSDOS.SysCommand.Com
Config.SysAutoexec.bat
Mandatory
Should be present in the
bootable drive
If not found, then the
message,"Non-system
disk or disk error -Replace and press any
key when ready"
Optional
9. The boot strap loader first loads the IO.Sys file.(responsible for Input Output in the DOS
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(responsible for Input Output in the DOSenvironment.)
10.The next file that is loaded is the MSDOS.syswhich is the core of the DOS operating system.(responsible for Memory management andProcessor Management in the DOS environment.)
11.The MSDOS.Sys file now searches to find the
name of the command interpreter in theConfig.Sys file and when it finds one, it loads thesame onto the memory.
12.If no command interpreter is specified in theConfig.Sys file, the Command.Com file is loadedas it is the default command interpreter of DOSOperating system.
13.You can load a different command interpreter byspecifying the following in the Config.Sys file.
14.The last file to be loaded and executed is
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14.The last file to be loaded and executed is
the Autoexec.bat file that contains a
sequence of DOS commands.15.Now, the prompt is displayed and you
can see the drive letter of the bootable
drive displayed on your screen indicative
of the fact that the Operating System has
been loaded successfully from that drive.
B t Di
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Boot Disc
What?
A boot disk will allow you to boot off of a
diskette instead of your hard drive. Thisdiskette can be used to fix issues that may
arise during the lifetime of your computer.
C ti Wi d XP b t di k
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Creating a Window XP boot disk
The Microsoft Windows XP CD is abootable CD and in many cases you
should not need a bootable floppy
diskette. Booting from the Windows XPCD will allow you to not only install/re-
install Windows XP but will also allow you
to troubleshoot it.
I t t fil i B t Di
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Important file in Boot Disc
Boot.ini - which contains configurationoptions for a boot menu.
NTLDR - which contains the main Boot
loader itself
Ntdetect.com - To load an NT-based OS
(NTLDR is actually required. If boot.ini is missing, NTLDRwill default to \Windows on the first partition of the first harddrive. Many desktops in the home are in this configurationand a missing boot.ini file will simply generate an error
stating it is missing, then boot into Windows successfully.)
Create MS-DOS bootable
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diskette
When formatting a floppy diskette, users have theoption of creating a MS-DOS startup disk,
follow the below steps to do this.
1. Place diskette in the computer.2. Open My Computer, right-click the A: drive and
click Format.
3. In the Format window, check Create an MS-
DOS startup disk.
4. Click Start
How to use a boot diskette
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How to use a boot diskette
1. Place the diskette into write-protect mode (in case avirus is on the computer, this will not allow the virusto transfer itself onto the diskette).
2. Insert the diskette into the computer and reset or
turn on the computer to begin the boot process.3. As the computer is booting, answer the questions
prompted (if any).
4. Once at the A:\> take the appropriate actions
depending upon the situation of the computer.
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Resources System
Interrupt Request (IRQ)
DMA Channel
I/O Addresses
Interrupt Requests (IRQ)
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Interrupt Requests (IRQ)
What? IRQ manage various hardwareoperations. Devices such as sound cards,modems, and keyboards can all sendinterrupt requests to the processor.
Example: when the modem needs to run aprocess, it sends an interrupt request tothe CPU saying, "Hey, hold up, let me do
my thing!" The CPU then interrupts itscurrent job to let the modem run itsprocess.
IRQ (2)
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Q ( ) It is important to assign different IRQ addresses to
different hardware devices - the interrupt requestsignals run along single IRQ lines to a controller.
This interrupt controller assigns priorities to incomingIRQs and sends them to the CPU.
Since the interrupt controller can control only onedevice per IRQ line, if you assign the same IRQaddress to multiple devices, you are likely to get anIRQ conflict. This can cause a range of errors from not
allowing network connections to crashing yourcomputer.
So make sure you assign unique IRQs to newhardware you install and avoid the frustration and
keyboard throwing that conflicts can cause.
Direct Memory Access (DMA)
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Direct Memory Access (DMA)
Method of transferring data from the computer'sRAM to another part of the computer without
processing it using the CPU.
While most data that is input or output from yourcomputer is processed by the CPU, some data
does not require processing, or can be processed
by another device.
In these situations, DMA can save processingtime and is a more efficient way to move data from
the computer's memory to other devices.
DMA (2)
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DMA (2)
For example, a sound card may need toaccess data stored in the computer'sRAM, but since it can process the dataitself, it may use DMA to bypass the CPU
In order for devices to use direct memoryaccess, they must be assigned to a DMAchannel. Each type of port on a computer
has a set of DMA channels that can beassigned to each connected device.
I/O Addresses
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I/O Addresses
Resources used by virtually every devicein the computer.
Conceptually; they represent locations in
memory that are designated for use byvarious devices to exchange information
between themselves and the rest of the
PC.
I/O Addresses Spaces
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I/O Addresses Spaces
Unlike IRQ and DMA channels, which areof uniform size and normally assigned one
per device, some devices use more than
one because many devices wrapped intoone package such as sound card.
I/O addresses vary in size - some devices
have much more information to movearound than others
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Motherboard Fault Symptoms
Basic Troubleshooting Method
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Basic Troubleshooting Method
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