Basics of Computer

Computer:

Computer is an electronic device that stores, retrieves, and processes data, and can be programmed with instructions. A computer is composed of hardware and software and can exist in a variety of sizes and configurations.

Block Diagram:

Hardware:

The physical components of your computer such as the system unit, mouse, keyboard, monitor etc are called Hardware.

Software:

The software is the instructions that make the computer work. The software is stored either on your computers hard disk, CD-ROM, DVD or on a diskette (floppy disk) and is loaded (i.e. copied) from the disk into the computers RAM (Random Access Memory), as and when required.

INPUT DEVICES:

 Scanners: A scanner allows you to scan printed material and convert it into a file format that may be used within the PC

 TouchPads:  A device that lays on the desktop and responds to pressure

 Light Pens:  Used to allow users to point to areas on a screen

 Joysticks:  Many games require a joystick for the proper playing of the game

OUTPUT DEVICES 

 VDU:  The computer screen is used for outputting information in an understandable format

 Printers: There are many different types of printers.  In large organizations laser printers are most commonly used due to the fact that they can print very fast and give a very high-quality output.

Plotters : A plotter is an output device similar to a printer, but normally allows you to print larger images.

Speakers : It gives output as the sound it is used for ICT enabled educational and presentation of products.

Memory/ Computer Storage:

Memory is generally Classified as Primary Memory and Secondary Memory

Primary Memory: RAM and ROM are normally called as Primary memories

RAM - Random Access Memory:

The main 'working' memory used by the computer.When the operating system loads from disk when you first switch on the computer, it is copied into RAM. computer will operate faster if you install more RAM. Data and programs stored in RAM are volatile (i.e. the information is lost when you switch off the computer)

ROM – Read Only Memory:

Read Only Memory (ROM) as the name suggests is a special type of memory chip that holds software that can be read but not written to.  A good example is the ROM-BIOS chip, which contains read only software.  Often network cards and video cards also contain ROM chips. Normally ROMs are  Non- volatile (i.e. the information is lost when you switch off the computer)


Secondary Memory

Secondary Memories are  Non- volatile storage devices (i.e. the information is lost when you switch off the computer). Example of Secondary Storage devices are Hard disk drives which are an internal, higher capacity drive; also stores the operating system which runs when you power on the computer.
Floppy, CD-ROM, DVD are also examples of Secondary Memory.

How Computer Memory is Mesured:

 Bit: All computers work on a binary numbering system, i.e. they process data in one's or zero's. This 1 or 0 level of storage is called a bit.

Byte: A byte consists of eight bits.

Kilobyte: A kilobyte (KB) consists of 1024 bytes.

Megabyte: A megabyte (MB) consists of 1024 kilobytes.

Gigabyte: A gigabyte (GB) consists of 1024 megabytes.

Microprocessors: Microprocessor is a single chip that acts as CPU of a Microcomputer.
Examples: Intel 386, 486, Pentium, Dual core, i3,i5 etc. Microprocessor mainly includes ALU and CU (Control Unit).


Types of Computers:

Super Computers:

supercomputers are used for scientific and engineering applications that must handle very large databases and great amount of computation. PARAM developed by CDAC is an example of supercomputer.


Mini and Mainframe Computers:

Very powerful, used by large organizations such as banks to control the entire business operation. Very expensive!

Personal Computers or Microcomputer:

Cheap and easy to use. Often used as stand-alone computers or in a network. Maybe connected to large mainframe computers within big companies. Personal computers can also be connected to the Internet using modem.





Factors affecting the  Performance of a Computer:

1. CPU speed  (Measured by its MHz or GHz speed.
2. RAM size  (Measured in GB)
3. Hard disk speed and capacity (Capacity Measured in GB or TB)

Types of Software:

Operating systems:

It is also called system software; which acts as an interface between the hardware and the user. The operating system is a special type of program that loads automatically when you start your computer. The operating system allows you to use the advanced features of a modern computer without having to learn all the details of how the hardware works. Eg: Widows XP, Windows 7 etc

Applications software:

Types of programs which are used for specific applications. An application program is the type of program that you use once the operating system has been loaded. Examples include word-processing programs, spreadsheets and databases

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