Inside the Main System Unit

Inside the Main System Unit

Inside the Main System Unit

Let us now see the components inside the main system unit.


·        Motherboard


The main component inside the main system unit is the motherboard. This is the biggest electronic circuit board are attached.


The boards that attach to the motherboard are known as daughter board are known as daughter board or expansion board.


The motherboard contains many important components, such as


  • The CPU (computer’s brain)
  • RAM & ROM – computer memory
  • Many support chips for the CPU and
  • Expansion Slots to Connect Peripheral.



·        CPU


CPU or the Central Processing Unit is the brain of the computer. The mathematical operations such as addition, subtraction etc. A logical process such as comparing of two values is done by CPU.


The CPU is also known as Microprocessor.



·        Memory (RAM & ROM)


For any mathematical or logical operation, CPU requires some memory. This memory is used to store the initial values, intermediate results and the final results, during any operation.



·        CPU Support Chips


With the CPU and memory, motherboard also contains some support chips or ICs. These chops help the CPU in carrying out its various activities.


Some of the common support chips are DMA Controller, Interrupt Controller, Keyboard Controller, Timer etc.



·        Chipset


Current motherboards provide different functions provided by the support chips on a set of chips known as chipset. These chipsets are made by various motherboard manufacturers, such as Intel, Optic, Via etc.



·        Expansion Slots to Connect Peripheral


The motherboard contains many expansion slots, long narrow connector towards the back of the computer. On these slots different expansion cards can be connected to attach various peripherals devices to the computer.


These expansion slots provide path to device connected to them to communicate with the CPU and memory on the motherboard.



·        Storage Device


Main system unit also-contain the storage devices. These devices are used by the computer to store various information.


Some storage devices such as floppy disk and hard work on the principal of electromagnetism; currently storage devices that use light to read/write data on optical disc are becoming popular, these discs are known as CD-ROM (Compact Disc-Read Only Memory) disc.


Some of the common storage devices are


  • Floppy Disk Drive
  • Hard Disk Drive and
  • CD-ROM/DVD Drive


·        Power Supply


Power supply is the heart of the computer system. Like the human heart pumping blood to different parts of the body, the power supply provides various parts of the computer with clean DC power supply to keep the computer alive and functioning


The Power supply converts high voltage AC mains supply to DC power required by the computer.


The power supplies are rated in watts, currently power supplies of 260 or higher wattage are common.


A fan assembly is provided in the power supply to keep the computer cool. If this fan fails, the computer may overheat and start giving intermittent problems or may completely stop working.

·        Monitor


Monitor or the VDU (Visual Display Unit) is a television like output device. It is used to show the result of processing done by the computer. Monitor can be used to show text. Number, or graphic image such as a charts, figures etc.


The monitor is available in many different sizes. Size of monitor is measured diagonally, a common monitor size is 15 inch, and for designing and desk top publishing (DTP) purposes 17 inch or bigger monitor is preferred.



·        Keyboard


Keyboard is the main input device for computer. Format of computer keyboard is similar to the typewriter keyboard’-so that a traditional typist can use the computer keyboard without any trouble.



·        Mouse


A mouse is basically a pointing device about the size of palm. It roll on a small ball and has one or more buttons on the top. When the user rolls the mouse pointer moves in the direction of the mouse’s movement.


The “Mouse” is basically made for Graphical User Interface applications, but, compared to choosing an option using the cursor control key using a mouse is more natural, even in the text based environment.


The mouse can never replace the keyboard, but can supplement the keyboard by doing tasks such as moving the cursor and pointing to on- screen objects, tasks for which the cursor movement arrow keys are ill-suited.


·        Printer


Printers are output devices, they are used to get the computer output on a paper, envelop, OHP transparency sheet etc. Output produced by printer is known an “hard copy”, because these outputs are permanent compared to the information displayed on the monitor, which is known as “soft copy”.


Three types of printers are commonly used with the personal computer (PC).

They are


  • Dot-matrix
  • Ink-jet
  • Laser


The quality of a printed output is measured in the number of dots printed by the printer, in per square inch of area. This is known is DPI (Dots per Inch) value.


Dot-Matrix printers have lowest DP value, laser and ink-jet printers are available for 300 and more DPI value.


·        Modem


The modem is a device which allows you to connect your computer to any other computer, anywhere else in the word using a telephone line.


This allows you to communicate with the connected person, transfer data, copy software/program from the connected computer, sent and receive mail using e-mail etc.


Currently, the modem can also be used to send and receive fax, for this you can use modem as a fax devices. To connect to the Internet or the WWW (Word Wide Web), one requires a modem.


  1. Internal Modem and
  2. External Modem