Bus

What is Bus?

Bus is an electronic road along which signals are send from one part of the computer to another.

This lines you see on the Motherboard are the buses that take data, address, control signals and power from one pace to another on the Motherboard.

Depending on their use, bus is divided into three major types.

• ·         Data bus

• ·         Address bus

• ·         Control bus

When someone talks about the bus, without specifying its type, the most probably he is talking about the data bus.

·        

 The data bus is used to move data from one place to another. The number of the data lines provided in the bus is very important factor that determines the speed of this data transfer.

·          

The address bus is used to select a particular memory location read or write the data. Maximum memory that CP can address depends on the size of its Address Bus.

·         The control bus is used to send control and timing signals between various parts of the computer.

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Position Of The Motherboard

Inside the main system unit, position of the motherboard depends on the model/type of the cabinet used.

Inside a tower model cabinet, the motherboard is attached to one side of the system box, normally it is placed just below the power supply.

On a Desktop model cabinet, the motherboard is placed at the base of the system box, next to the power supply.

Motherboard is connected to the cabinet with about half inch high plastic spacer in between the board and the cabinet at various places.

This protects the components on the motherboard from touching the cabinet’s bottom metal surface and short circuiting themselves.

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Introduction (Motherboard)

Motherboard is the most important component in the any Personal Computer. It contains almost every important parts of the computer system.

Normally, the motherboard contains the CPU or the brain of the computer, memory ( RAM, ROM etc.) and support circuits to make the computer work.

Motherboard also contains many Expansion Slots on which you connect various circuit boards. These circuit boards are used to connect different devices such as monitor, printer, scanner etc. with the computer.

This main board is called Motherboard because all other circuit boards, inside the computer, are attached to this board i.e. it is the mother of all boards.

As this main board is called motherboard, all other boards attach to it are called “Daughterboard”.

Sometimes the size of the daughterboard could be bigger than the motherboard. But, most of the time motherboard is the largest circuit board inside a personal computer.

Mother contains

• CPU (Microprocessor),

• Co-Processor (optional),

• CMOS Memory,

• Real Time Clock (RTC) Circuit,

• Memory (RAM & ROM),

• BIOS,

• Support Chips / Chipset to help CPU to deal with Input / Output, Interrupts, DMA etc.,

•  Expansion Slots

On the Motherboard Printed Circuit Board (PCB), the components are placed and connected with the help of thin copper tracks. Motherboard PCB contains many such tracks to make electrical connection between different parts of the system.

Generally these tracks are very fine, and one should never put excessive pressure on the board while inserting or removing cards or chips, if the board bends excessively, these tracks could develop small hairline cracks.

Once a track is broken, because of the multiple layers of tracks, it is almost impossible to trace the broken area and repair it.

When evaluating the quality of the motherboard one should consider

• The thickness of the board. Most cheaper boards are quite thin and they cannot withstand careless handling or frequent insertion and removal of the expansion cards.

• The quality of the soldering. The soldered joints of good motherboard should be bright not foggy.

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Starting The Computer

Once all the required devices are properly connected to the main computer unit, you can switch o the system. Start the computer by first switching on the AC mains switch, power conditioning device (UPS, stabilizer etc.) switch and power on switch provided on the front panel or the back of the main system unit.

Turn on the monitor, turn on the Printer, the external modem, and the speaker if you require their service.

When the main unit is turned on you will hear the main unit power supply fan’s rotation sound. After some time the computer will produce a single beep sound to indicate that all its parts are working properly.

Before producing this beep sound, computer does a POST (Power On Self Test) operation. During POST, computer checks most of its parts to make sure that they are working normally.

During the POST, If the computer finds that a part is not working as expected, then it will display some error message or produces some combination of beep sounds to inform that something is wrong with the computer.

These beep sound combinations is called Error-Beep Codes.

If everything is all right with the computer then, after POST, the computer will produce a single beep sound.

After this beep, the computer needs a software called Operating System (OS). This Operating System or OS or DOS (Disk Operating System) is stored on some storage device such as a floppy disk, hard disk drive or CD-ROM is provided to the computer during the power on process.

Computer reads the Operating System (OS) from the storage device into its memory i.e. the RAM. This process of loading the OS from storage device into the computer memory is called “Booting of the Computer”.

This booting process is repeated whenever the computer is switched on, because every time power supply to the computer is switched of, the information stored in the computer’s memory (RAM) is lost.

Some of the OS available in the market are, MS-DOS, Linux, Unix, MS-Window, OS/2, DR DOS etc. Out of this operating systems the Windows developed by Microsoft Corporation is most common Operating System in the PC environment.

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Connecting Different Devices

This section explains how to connect different input and output devices such as Keyboard, Monitor, Printers etc. to the main computer system.

Remember that connecting or disconnecting any device to the computer must be done in the computer and device power off condition. If the power supply to the device or the computer is on then this could damage the computer, the device being connected, or both.

Power Cable

To provide power to the computer, a power conditioning device such as stabilizer, CVT (Constant Voltage Transformer) or UPS (Un-interruptible Power Supply) is first connected to the AC mains supply.

The UPS is the best power conditioning device, as it takes care of almost all power problems such as spike (very high over-voltage that lasts for less than a millisecond to a second), surges (over-voltage that lasts for few milliseconds to a second), under-voltage, brown-out, black-out, over-voltage etc. The UPS also provides back up power to the computer in case of any power failure.

The output from this power conditioning device is given to an extension box, to which different devices are connected.

Based on the type of power connector provided on the monitor, a monitor can be connected to the output on the power supply of the computer or it can be connected to the extension box.

Monitor

After connecting power cable to the monitor into the computer’s power supply or into the power extension box, another cable known as data cable from the monitor needs to be connected to the computer system.

9-Pin female or 15-Pin female D-Shell socket at the back of system unit is used to connect monitor to the computer system.

•  The 9-Pin socket is used to connect Monochrome, HGA (Hercules Graphic Adapter), CGA, EGA or Dual display (which supports both HGA & CGA) monitors to the computer system.

• The 15-Pin socket is used to connect currently available VGA or SVGA monitor to the computer system

Keyboard

The keyboard is connected to the small round opening provided at the back of the main system unit.

When connecting the keyboard to this socket make sure that a small notch on the socket and on the keyboard connector are properly aligned, otherwise the pins of the keyboard connector will not aligned with the holes provided on the socket.

Once the connector and socket are properly aligned, insert the keyboard connector fully into the socket.

Currently many Keyboards come with USB, PS/2 Mini-DIN or wireless connector. Check the connector provided with the keyboard and attach to proper socket on the main system unit.

Mouse

A mouse is connected to serial port socket provided at the back of the main system unit. Generally, the computer ha two serial ports COM1 and COM2 (Com stands for Communication Port).

Most of the software provided with Mouse can automatically detect the serial port at which the mouse is connected.

Currently many mouse come with USB, PS/2 or Wireless connectors. Check the connector provided with the Mouse and attach to proper socket on the main system unit.

Printer

Printer is connected to the 25-Pin female D-shell socket provided at back of the main system unit. Socket for serial device is a 25-Pin male D-shell socket.

Cable for connecting printer to the computer has a 25-Pin male D-shell connecter at one end and has a special type of connector known as Centronics Connector at the other end.

The 25-Pin male D-type connector on printer cable is connected to the 25-pin female D-type socket on the main system unit and the other end of the cable with Centronics Connection is connected to the Centronics socket on the printer.

Currently many printers come with USB, and Wireless connection. Check the socket provided on the printer and connect to the proper socket on the main system unit.

Speaker/Microphone

Speaker and Microphone are connected to the output provided at the back of the sound board. Back of the sound board contain jacks for connecting the microphone and a set of speakers.

Using proper cable, speaker output can be connected to an audio amplifier, or home stereo system to produce high volume sound output.

Modem

If you are using an external modem, then connect the modem to the serial port on the computer unit.

If you are using an internal modem comes as an expansion card and is directly connected inside the computer to one of the expansion slots.

If you want to see the same telephone line for normal voice communication as well as for the data communication then connect the modem to the telephone line and a telephone instrument can be connected to the line out provided on the modem.

Connect a RJ-11 cable to the phone socket provided on the wall , connect other end of this cable to the line socket provided on the modem.

One end of another RJ-11 cable should be connected to the phone socket provided on the modem and the other end of this cable can be connected to a telephone instrument.

This allows same line to be used for voice as well as data communication.

If you are using external modem, then connect the power supply provided with the modem to the power socket.

Next 

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Access Files On LAN Computers

Today I am going to show you how to get full control of files contain by computers in LAN. This trick is useful for getting question papers in your school, get important documents in your office. so lets start.
1. Click on Start > Programs > Accessories
2. Right click on 'CMD'
3. Click on properties.
4. Enter in 'system 32'
5. Search "ddeshare' without quotation mark
6. Double click on 'ddeshare'
7. Go to shares and click 'trusted shares'
8. Click on system you want.
DONE. You are Successful.

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