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What is the computer?Computer is the fast electronic device. That is used to get the input

from the user manipulates the calculate and produce output.

A device by which data given in an appropriate form can be manipulated insuch a way as to produce a solution to problem in. information processing,the term computer usually describes a digital computer. A computer mayconsist of a stand alone unit or a combination of several interconnected units

Generations of Computer

GenerationYear

Electronic component

used

1st Generation1950

Electronic volve

2nd Generation1960

Transistor

3rd Generation

1966

Integrated circuit

4th Generation1975

Micro processor

5th Generation1980

L.S.I.S (Large scaleinference )

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Hints:-

In 19th century Charles Babbage Invented Differential Calculator and

Analytical Machine.

Differential machine

Algebra Sums 20 Digit system

Analytical machine

The first invented computer is the Automatic computing device. Sixty additions problem is doing in one second.

ENIAC (Electronic numerical Integrator and calculator)In 1946- J.P Eckret and J.wMauchly

5000 Additions and 350 Subtract Do in one Second 18000 Volve, 70,000 Resisters, 60,000, Switch 150 kilowatt

Electricity.

Classifications of Computer

Personal Computer (Desktop machine):

The most Popular Computers are Desktop Machines. They are used forPersonal and official Purposes. They are having high higher capacity diskStorages and main memories on account of multimedia devices. Theapplication is user friendly and very effective.

Work Station or Mini Computer:

They are also desktop machines. However they are more powerfulproviding processor Speeds about 10 times of Pcs. Most workstations havebuilt in hardware to connect to a LAN.

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Laptop pcS:

Laptop Pc is also known as notebook computer and portable Weighingabout 2 Kg. They run with batteries and are thus designed to conserveenergy.

Mainframe Computer:

These Computers are much bigger than workstations and severalHundred times more expensive. They are used in banks and insuranceCompanies which process large number of transactions. They requireComputers with Large disks to storage and with large main memory.

Super Computer:

These Computers are very Large Systems in which billions and

billions of data will be processed. In addition, the rate of data transfer willbe very high, as it involves in billions of data sets. These Systems are used inScientific and Research purposes.

BASIC COMPUTER OPRETIONS

3

Input unit

Arithmeticand Loge Unit

Control Unit

OutputStorage Unit

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Input unit:

The input unit supplies the data to the System toperform Calculation. It accepts or read the instructions from the outsideworld. It converts these instruction and data in Computer acceptable from.Then Supplies the converted instructions and data to the System forfurther processing.

Output unit:

The output unit is reverse of the input unit. It accepts theresult produced by the computer, which is in coded format, hence cannot be

easily understood by us. It converts the coded results to human acceptablefrom. It supplies the converted result to the outside world.

Arithmetic Logic unit:

ALU is the place where the actual execution of the instructiontakes place during the processing operations. All comparisons and are takeplace here.

Control Unit:

The control unit contains the micro code and the circuitry thatcarries out calculations to locate the proper addresses for the execution ofthe micro code.

Central processing Unit:

The ALU and Control unit of a computer system are jointly known asCPU. The CPU is responsible fro activating and controlling the operations ofother units of a computer system.

Storage Unit

The data we feed into the computer through input unit forcalculations have to be stored before processing and similarly after the

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processing the data has to kept somewhere in the computer before passedon to the output unit. To meet these needs storage unit is formed.

Number system

Modern computers do not process decimal numbers. Instead they work withbinary numbers, which use only two digits 0 and 1. This creates hugeproblem to very long when representing larger binary quantities. Thereforeoctal and hexadecimal numbers are used to compress long string of binary.

Binary number system:

Digital computers and systems are based on binary (two state)operation ex.. Power switch, punch card, clock pulse etc. the binary number

systems or base 2 number system has only digits 0 and 1.

Decimal Binary

0 0000

1 0001

2 0010

3 00114 0100

5 0101

6 0110

7 0111

8 1000

9 1001

10 101011 1011

12 110013 1101

14 1110

15 1111

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Decimal to binary

Ex.(45)10

2 45

2 22 -1

2 11 -0

2 5 -1

2 2 -1

1 -0

(45)10 = (1001011)2

Binary to decimal:

(101101)2

1*25+0*24+1*23+1*22+0*21+1*20

= 1*32+0*4+1*8+1*4+0*2+1*1=32+0+8+4+1= (45)10

1010- Each digit in this number is a bit

8 bits = 1 Byte1024 Bytes = 1 Kilobyte (KB)

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1024 KB = 1 Megabyte (MB)1024 MB = 1 Gigabyte (GB)1024 GB = 1 Terabyte (TB)

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Mother Board components

It is used to connect all input and output unit and devices. It consists of thefollowing parts.

1. Processor socket2. Memory slot3. IDE slot (Integrated drive electronics)4. Floppy disk drive controller5. PCI slot

6. Parallel port7. DIN Connectors8. PS/2 Connector9. USB connector (Universal serial bus )10. Power connectors11. VGA Connector12.AGP Slot13. Memory modules14. Other supporting chips

15. Front panel indicator controller

1.Processor socket is nothing but a place we place the processor. On aPentium based computer the processor is in a ZIF (Zero insertion Force)socket. Formerly used sockets are standard sockets as LIF (Less insertionforce) Ex. Socket 370, 478, LGA 775 etc.

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Processor

It is the brain of the computer that is capable of performing arithmeticand logic function as defined by a given program,

Name Min. Speed Max. Speed

8086(IBM

Starting)

4.77 MHz 10 MHZ

8088 4.77 MHz 10 MHz80286 10 MHz 16 MHz

80386 16 MHz 40 MHz

80486 40 MHz 100 MHz

Pentium I 100 MHz 133 MHz

Pentium II 133 MHz 350 MHz

Pentium III 350 MHz 866 MHz

Pentium IV >800 MHz 3.6 GHz

2. Memory SlotIt is used to insert the primary memory of RAM there are threememory slot available in the mother board.

SIMM- Single inline memory moduleDIMM- Dual inline memory moduleRIMM- Rambus inline memory module

3. IDE Connector

It is a 40 pin connector It is used to connect Hard disk and CD ROM Generally two IDE connectors are available in mother board IDE1 ,IDE2 Both IDE cables construct to sections master and slave,

4. FDD Connector

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It is a 34 pin connector particularly this data cable in built jumperssettings.

5. Serial port

It is a 9- pin & 25 pin male connector. it is used to connect mouse andmodem.

6. Parallel port

It is a 25 pin female connector It is used to connect printer and scanner The data is transferred byte by byte

7. DIN (Dutch industry norm)

It is a 5 pin connector It is used to connect keyboard

8. PS/2 connector

It is a 6 pin connector It is used to connect keyboard and mouse

9. USB port (universal serial bus ) It is used to connect all input and output device Data transferring speed is high

10. Power connector

There are two connectors AT(Advanced technology) ATX(Advanced technology Extension)

AT(Advanced technology)

It is a 12 pin connector External shut down Power consumption less

ATX (Advanced technology Extension)

It is a 20 pin connector

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Automatic shutdown Does not require a switch High power consumption

PCI Slot (Peripheral component interface (connect)) It is used to connect all input and output devices Ethernet card TV-Tuner card Internal modem

VGA Slot (Video Graphical array)

It is a 15 pin connector 3 rows female connector It is used to connect monitor data cable

Switch Mode Power Supply

The digital logical circuits of the Computer System are given

electric power using SMPS. It converts the Alternative Current to

Direct that is required by the electronic circuit. The electronic circuit

of the PC, such as processor and memory require very low voltages

(+3.3v to + 5v Dc). Hard disks and other permanent storage devices

need +12v Dc. The SMPS produces various DC Voltages in the range of

-12v Dc to +12vDc.

There are two factors in the power supply. They are (1) AT

Advanced Technology (2) ATX Advanced Technology Extended.

AT type power supply

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AC

IN

AC

OUT

On/OFF

Switch

Various

DCVolts

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ATX Type power supply

ATX SMPS Various DC Volts

Pin Description Color

01 +3.3V Orange

02 +3.3V Orange

03 Signal Ground Black

04 +5V Red

05 Signal Ground Black06 +5V Red

07 Signal Ground Black08 Power Signal Ground Grey

09 +5V Red10 +12V Yellow

11 +3.3V Orange

12 -12V Blue


14 Power Switch ON Green15 Signal Ground Black


17 Signal Ground Black18 -5V White

19 +5V Red

12

AC

IN

AC

OUT

Process

orPower

Supply

Various

DC

Volts

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StorageDevices

Primary Secondary

ROM RAM Floppy

CDD

HDD

20 +5V Red

Storage Devices

ROM (Read Only Memory)It is a kind of memory that cannot be altered. It can only be read. ROM

is non Volatile. (its content are safely held even after the power source isremoved). Thus it is an ideal place to store system startup instruction.Typically BIOS is stored on ROM Chip, and thats why it is often referred asROM Bios.

Types of ROM:PROM (Programmable ROM):

A type of ROM that cannot be programmed once, data has been writtento it with a H/W devices known as PROM Kit.

EPROM (Erasable PROM):

It can be programmed only if the chip is exposed to UV light when itsprotective top cover is removed.

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EEPROM (Electrically EPROM):

It can be reprogrammed by just passing some particular voltages andreprogrammed.

RAM (Random Access Memory)

RAM is also known as main memory or system memory. Every piece of dataand every instruction processed are executed by the CPU are stored in theRAM.

Types of RAM

SRAM

The static RAM requires more physical board space to store the sameamount of data as DRAM. SRAM doesnt need to be refreshed as it providesfaster access speed is 15 ns to 30 ns.EDO RAM: (Extended Data out RAM)

A kind of DRAM it improves system performance by allowing fasterread times than any DRAM of comparable speed.

BEDO RAM (Burst EDO RAM)

Similar to EDO RAM but the amount of memory data transferred at atime is more than the EDO Chips.

DRAM (Dynamic RAM)

The most common form of RAM is Dynamic RAM of DRAM. EachDRAM storage cell contains a capacitor, which holds one bit of data orinformation. The DRAM must be refreshed every 2 milliseconds. DRAM isinexpensive and store large number of bits on a single small chip.

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RAM

SRAM DRAM

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SIMM (Single inline memory module)

FPM (Fast page mode), 30 pins no cut EDO Extended data out RAM ,72 pins center cut.

DIMM (Dual memory module) SDRAM (Synchronize dynamic RAM , 168 pins near

center cut , near end cut DDR1 (Double data rate RAM , 184 pins near

center cut DDR2 (Double data rate RAM, 184 pins near center

cut

DRAM

SIMM DIMM RIMM

FPM EDO SDRAM DDR1 DDR2

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RIMM (Rambus inline memory module)RD RAM 184 Pins, 2 cut near center

External Storage Device

Floppy Disk Drive;

It is used for storage Invented by IBM 1981

The recording medium of floppies is a vinyl plastic material with magneticcoating on one or both sides. These plastic disks coated with magneticmaterial are permanently sealed in a square plastic jacket to protect themfrom dust and scratches.

As floppy disk is a direct access type of storage medium, the timerequired in a magnetic tape.

Two types

Mini Floppy (5 Diameter)Micro Floppy (3 Diameter)

The number of tracks ranges from 35 to 40 on a mini floppy and from 50 to80 on a microfloppy. The tracks are physically divided into sectors.

The classification of floppies is based on the capacity of the quad

density floppy will be two times the capacity as a double density floppy and4 times the single density type.Used materials

Ferrous Cobalt Barium

Motors Step motor used to move the head Spindle motor-used to rotate the disk

Connectors Power connector IDE connector

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Hard diskA hard disk is a mass storage device, which is a fixed disk, needed for

direct access. Thus it retrieves any record of data at a very fast speed.

StructureHard disk is a disk pack consists of a number of disks. In a disk pack,

information is stored on both the surface of each disk plate except theupper surface of the top plate and the lower surface of the bottomplate, which or not used. Each disk consists of a number of invisibleconcentric circle called tracks. A set of corresponding tracks in all the

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surface is called a cylinder. Thus a disk pack having 10 disk plates willhave 18 recording surfaces and hence it will have 18 tracks per cylinder.Each track is further subdivided into sectors. Information is recordedon the tracks of a disk surface in the form of invisible tiny magnetic

spots. The presence of magnetized spot represents a 1 bit and itsabsence represents a 0 bit. The information stored on a disk can be readmany times with out erasing the stored data. So the reading operation isnon-destructive. But writing of new data erases the data previouslystored at the location of the disk. The data stored on a magnetic diskremains for an indefinite period until erases.

CD ROMIt is an optical ROM. Prerecorded data can be read out.

Working principleThe disk is made up of a resin, such as polycarbonate. It is coated

with a material which will change its reflecting property when a highintensity laser beam forms a tiny bit along a trace to represent 1 andthe surface with out a bit known as land represents 0. For readingthe data laser beam of less intensity is employed. CD ROMs use longspiral tracks to stored data serially. A CD ROM disk rotates at avariable speed so that the bits are read by the laser at a constant liner

speed. The speed of the disk is adjusted in such a manner that the trackpassed under the read/ write head at a constant linear velocity.

TROUBLE SHOOTINGSystematic Problem Solving ApproachThe stranded problem-solving process has six steps.

1. Identify the problem.2. Identify possible causes.

3. Identify possible solutions.4. Analyze the possible solutions.5. Apply the solution.6. test the solution.

1. PC is dead

If the PC is dead and will not start up.

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1. Make sure the PC or the monitor and both plugged into an activeAC outlet.

2. Check the outlet by plugging in a lamp or another device.3. Move the plug to a new outlet.

4. Replace the power cable.

2. Monitor

1. ensure that the monitor is connected to the video adapter installedin the PCs system unit.

2. Check both ends of the video cable for a snug connection.3. Check the monitors power cable.4. Check the brightness and contrast controls have not been turned

all the way up, which results in a dark screen.

5. Replace the monitor with a known-good monitor. If thereplacement monitor works, then there is something wrong withthe existing monitor. Repair it.

6. If the replacement monitor does not work, the problem is likelywith the video adapter card.

7. Reboot the pc. Listen for beep codes and watch for error messagefrom the POST.

3. Power supply

1. Check the out put DC voltages on the appropriate pins.2. If the power supply is not producing the correct voltages or the

fan is having problems, the power supply should be replaced. Thepower supply accounts for the majority of component failures inthe PCs, so do not hesitate to replace even a suspected bad powersupply.

3. Keyboard

1. Power off the computer and unplug the keyboard from themotherboard.

2. Power on the computer.3. Use a multimeter to check the voltages of the connectors pins.

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4. Replace the keyboard with a known good keyboard. If thereplacement keyboard also fails to work, the problem is likely onthe motherboard or its connector. Before replacing themotherboard because of a bad keyboard port. You may want to

consider a USB keyboard if a USB port is available.

5. HDD

1. Check the master slave settings.2. check the power connection. Try using a different power connector

from the power supply.3. verify that the red or blue edge of the data cable is aligned to pin14. Verify that the hard disk is formatted or not.

5. Mouse

1. Power off the PC disconnects the mouse.2. Turn the ring counter lock wise and removes the ball from the

mouse.3. Dampen lint free cloth with water or the alcohol and gently rub.

The ball, when the all has been completely wiped, let it air-dry.4. Use the swab and alcohol to clean the rollers or contacts inside the

ball cage and the interior of the mouse. If the rollers have a darkbuildup, gently scrape away the dirt with a small e blade.

5. Replace the ball in the mouse and replace and turn the retainingring clock wise to lock the ball in place.

8. Video card

1. Make sure the video card is firmly scatted in the appropriate busslot.

2. Verify that the video card has not been assigned system resourcesthat had already been assigned to another conflicting device.

3. Verify that the device is installed.4. Verify that the BIOS setting are correct for the video card.

9. Sound card

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1. Make sure the sound is turned up on the speaker and in the windowvolume control panel.

2. Check the speaker cables to make surety connected to both thespeakers and sound card.

3. Verify that the connectors are installed in the correct jacks.4. Check for resource conflicts.5. Make sure the sound cards device drivers are loaded.6. If no sound is coming from the CD-ROM drive, make sure that the

CD-ROM is connected to his sound card with the appropriate cable.

Beep Codes

Beeps Meaning

No Beep Power supply or system

1 Short POST is OK

2 Short POST error with error codedisplay on screen

Repeatingshortbeeps

Power supply or systemboard failure

1 Long, 1Short

System board error

1 Long, 2Short

Video display adapter failure

1 Long, 3Short

Video display adapter error

3 Long Keyboard error

AMI BIOS beep codes

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Beeps Meanings

1 Short POST is OK

2 Short Memory Failure

3 Short Memory/ Parity failure

4 Short System timer failure

5 Short Motherboard failure

6 Short Keyboard controllerfailure

7 Short CPU failure

8 Short Video adapter failure

9 Short ROM BIOS checksumerror

10 Short CMOS read/ write error

11 Short Cache memory error

1 Long, 3Short

Memory error

1 long, 8Short

Video adapter failure

1 Long Memory error

1 Long, 2Short Video error

1 Long, 3Short

Video failure

ContinuousBeep

Memory or video failure

Phoenix BIOS beep codes

Beeps Meaning

1-1-3 CMOS memory is corrupt

1-1-4 BIOS failure

1-2-1 System error

1-2-2 Motherboard error

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1-4-2 Memory error

2-x-x Memory failure( two beeps withany combination of beeps

3-1-x Chipscl error

3-2-4 Keyboard controller error

3-3-4 Video adapter failure

4-2-4 Expansion card failure

4-3-4 Time of day clock failure

4-4-1 Serial port error

4-4-2 Parallel port error

4-4-3 Math coprocessor error

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