Study of various components of computer

Experiment no 1

Aim:- Study of various components of computer like CPU, keyboard, mouse, monitor, printer, CVT and storage devices  

Theory:-    Introduction                                                                                                     .   

CPU (Central processing unit):-
The central processing unit (CPU) of a computer is a piece of hardware that carries out the instructions of a computer program. It performs the basic arithmetical, logical, and input/output operations of a computer system. The CPU is like the brains of the computer - every instruction, no matter how simple, has to go through the CPU. So let's say you press the letter 'k' on your keyboard and it appears on the screen - the CPU of your computer is what makes this possible. The CPU is sometimes also referred to as the central processor unit, or processor for short. So when you are looking at the specifications of a computer at your local electronics store, it typically refers to the CPU as the processor.

1. Input: this is the process of entering data and programs into the computer system.

2. Control Unit (CU): The process of input, output, processing and storage is performed under the supervision of a unit called 'Control Unit'. It decides when to start receiving data, when to stop it, where to store data, etc. It takes care of step -by-step processing of all operations inside the computer.

3. Memory Unit: Computer is used to store data and Instructions.

4.Arithmetic Logic Unit (ALU): The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison.

5. Output: This is the process of producing results from the data for getting useful information. The ALU and the CU of a computer system are jointly known as the central processing unit (CPU). You may call CPU as the brain of any computer system


Input devices accept data and instructions from the user.
Following are the examples of various input devices, which are connected to the computer for this purpose.

1. Keyboard
2. Mouse
3. Light Pen
4. Optical/magnetic Scanner
5. Touch Screen
6. Microphone for voice as input
7. Track Ball


A keyboard (as shown in figure 1.3) is the most common input device. Several kinds of keyboards are available, but they resemble each other with minor variations.
Keyboard in most commonuse is the QWERTY board.Generally standardkeyboard has 104 keys. Inthese keyboards, the cursorcontrol keys are duplicated to allow easier use of thenumeric pad.

A mouse is an electro-mechanical, hand-held device (as shown in figure 1. 4). It is used as a pointer. It can perform functions like selecting menu commands, moving icons, resizing windows ,starting programs, and choosing options .The most common mouse uses an internal, magnetically coatedball, to detect the movement of the mouse across a flat surface ,usually a desktop. Now a days Optical or laser mouse is used to d etect the movement. All windows based applications today aredesigned to work with a mouse. A mouse is used to replace hard-to-remember key combinations with easier "Point and Click " actions. However, it cannot substitute all keyboard operations. It can be alternative for commands based operations.

Light pen

An input device that utilizes a light-sensitivedetector to select objects on a display screen.A light pen is similar to a mouse (as shown infigure 1.5), except that with light pen you canmove the pointer and select objects on the display screen by directly pointing to theobjects with the pen.

Track Ball

Trackball, a pointing device, is a mouselying on its back (as shown in figure 1. 9).
To move the pointer, you rotate the ball with your thumb, your fingers, or the palm of your hand. There are usually one to three buttons next to the ball, which you use just like mouse buttons.The advantage of trackballs over mouse is that the trackball is stationary so it does not require much space to use it. In addition, you can place a trackball on any type of surface, including your lap. For both these reasons, trackballs are popular pointing devices for portable computers.


Output devices return processed data that is information, back to the user. Some of the commonly used output devices are:
1. Monitor (Visual Display Unit)
2. Printers
3. Plotter
4. Speakers
Out of all the output devices,monitor (as shown in figure1.10) is perhaps the most important output device because people interact with this device most intensively than others. Computer information is displayed,visually with a video adapter card and monitor. Information processed within the CPU, that needs to be visually displayed, is sent to video adapter. The video adapter converts information from the format used, in the same manner as a television displays information sent to it by a cable service.

Two basic types of monitors are used with microcomputers,

Which are as follows:

1. CRT

2. LCD
Cathode Ray Tube (CRT): CRT or Cathode Ray Tube Monitor is the typical monitor that you see on a desktop computer. It looks a lot like a television screen, and works the same way. This type uses a large vacuum tube, called cathode ray tube (CRT).
Liquid Crystal Displays (LCD): This type of monitors are also known as flat panel monitor. Most of these employ liquid crystal displays (LCDs) to render images.

These days LCD monitor are very popular.When people talk about the capabilities of various monitors, one critical statistic is the resolution of the monitor. Most monitors have a resolution of at least 800 x 600 pixels. High-end monitors can have resolutions of 1024 x 768 pixels or even 1280 x 1024 pixels. Thus monitors are available either in low resolution or inhigh resolution1


After a document is created on the computer, it can be sent to aprinter for a hard copy (printout). Some printers offer special features such as colored and large page formats. Some of the most commonly used printers are:

1. Laser Printer
2. Ink Jet Printer
3. Dot Matrix Printer

Laser Printer:

A laser printer produces high quality print that one normally finds     in publishing. It is extremely fast andquiet. Moreover, the operation of a laser printer is easy with automatic paper  loading and no smudging or messing up of ink ribbons. The fastest laser printer      can print up to 200 pages per minute in monochrome (black and
white) and up to 100 pages per minute in colour.

Ink-Jet Printer:

An ink-jet printer creates an image directly on paper by spraying ink through as many as 64 tiny nozzles. Although the image it produces is not generally quite as sharp as the output of a laser printer,the quality of ink-jet images is still high.
In general, ink-jet printer offers an excellent middle ground between dot matrix and laser printer. Like laser printer, an ink-jet printer is quiet and convenient, but not particularly fast.Typically, an ink-jet printer is more expensive than a dot-matrix  printer, but costs only half as much as a laser printer

Dot Matrix Printer:

The dot matrix printer was very popular at one point of time. It is a very versatile and inexpensive output device. In dot matrix printer the print head physically "hits" the paper through the ribbon and produces text (or images) by combinations of dots; hence the name dot matrix printer. Its speed is measured in characters per second (CPS). Although it is less expensive, it is louder, slower and produces lower print quality. Line Printer: A line printer is generally used with large computer systems to produce text based data processing reports. Line printers are high-speed printers with speeds ranging anywhere from 100 to about 3800 lines per minute. In the past, print quality on line printers was not high. Developments in technology are improving the print quality.


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