By Sanal Kumar

We have stepped into the new century by now. A new window is open to unravel still undiscovered complexities and capabilities of the magic box of the past era, the computer. We all use computers everyday to lower burdens of our life some way or other. However many of the daily users are still finding it difficult to answer the simple questions such as what is a computer? What is inside that magic box? Do you know how it works? Do we need to know any complex Mathematics to learn about it? Will the computerization catalyze unemployment? A lot of questions can arise. Let us try to answer some of the questions in a simple manner that everyone could understand. It is also noteworthy to let all readers know that the technical terms are explained at the end of this article.

Computers were used in universities and for defense purpose in the United States of America, since long back. In the early 20th century, computers were manufactured in much larger boxes using a lot of mechanical and electrical equipment. The size of computers was very big to fill in a large room. After the invention of transistors in 1948 and Integrated Circuits in the next decade, the size of all electronic equipment became more compact. Now computers are being used in large scale in Integrated Circuits (VLSI) that allow us to integrate more than a million electronic components into a single silicon chip.

These days, you can find computers in schools, collages, banks, railway stations, airports, hospitals, offices, hotels and in many other communal places as helping hand to public. They are also serving crucial roles in accounting, engineering, architecture and in many other walks of life. They are intimate friends of our growing generations too.

Computers are divided into different categories depending on its size and use. They are Super Computers, Mainframes, Midi/Mini Computers and Micro or Personal Computers. The computers used in our homes and offices fall in the category of personal computers (PC). Since PC is used everywhere, let us briefly explain the main parts and working of a PC.

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When you look at PC, you will first notice the TV- like screen. This unit is called the Monitor or the display unit. A monitor shows you the result of what is happening in a computer. It displays our executions on the keyboard and the game and video you are playing. Since it gives you the output of what you need, it can be called as an output device.

Secondly, when you see a computer, you will have a motivation to type your name on it. You will use the Keyboard for this. Since you feed data to a computer using keyboard, it is an input device. A keyboard has all the alphabets of English, the numbers 0 to 9, some symbols, and some special keys.

Another important part of a computer is the Mouse. It looks like a mouse with a long tail and can easily rest in a single hand. It has a ball and socket assembly underneath. It helps the mouse to move the cursor on the screen smoothly when you move the mouse on a flat surface. The mouse is used to do the work faster. Usually it is kept on a pad with a slight rough surface. When you slide the mouse on the pad, a small arrow called a cursor moves on the screen. You can press the mouse button when your cursor is on the desired position on the monitor to complete a task.

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The most important part of the Computer is the big box, to which the monitor, the keyboard and the mouse are connected. This is usually referred to as the CPU unit. This unit contains the CPU (Central Processing Unit), Memory, Storage Units and other circuit boards to make them function and connect the peripherals (devices like printers, modems attached to a computer). The CPU processes all the jobs and calculations done by the computer. The Storage unit is used to store the information permanently. The memory is a temporary storage unit, which is required by CPU to complete its task.

If you look at the function of a computer, the input device feeds data to a computer. The data is processed by the Central processing unit and stores the required information in Storage Units. The results are sent to the output unit.

Besides these, a number of peripheral devices can be attached to a computer. Some of them are Modems, Fax Machines, Printers, Scanners and Plotters.

Now let us go and switch on the computer. When you switch it on, you can see some information on the monitor before you can use it. This is because, the computer tests its CPU, Memory, Storage Devices, Keyboard and all the internal devices. This process is known as Power On Self Test (POST). If anything is found faulty, it displays an error message on the monitor. A Computer Hardware Engineer can rectify this problem. The human made programs stored in the Read Only Memory (ROM) does this test. Once POST is completed, the computer looks for an Operating System (OS) in the Floppy Disk, Hard Disk, or CDROM. If the OS is found in any of these devices, the computer loads it in its memory. The process of loading the OS into the memory is known as booting the system. Before you work on a computer it must be booted. Once it is booted, it allows you to work on it using your keyboard and mouse. But, depending on your work, you must install the required man made program called Software.

Now you have got the preliminary idea about computers that can control the whole world by using a program. It means that computers are put into service using the programs that are 'man-made'. Without these programs (i.e. without the help of a man) a computer is really the biggest IDIOT of this world! On the other hand, behind every mega-machine or microchip, there is a true human brain.

Transistors: A transistor is an electronic device used in Radios and Televisions. It replaced the vacuum tubes (valves) used in the early 20th century. The size of a transistor is about 1/20 of a valve. A transistor consumes very less power compared to the vacuum tubes.

Integrated Circuits: A device in which a number of transistors and other electronic components integrated in a small silicon chip is called an Integrated Circuit (IC). Lately, the IC technology has become very much advanced and more than a million electronic components were embedded in a small silicon chip of 1 square inch in size. ICs are widely used in Computers, Televisions, Radios and all other electronic instruments.

Super Computer: large research agencies and military organizations use Super Computer technology. They are using a number of processors and attach computers to process information parallel to do complicated tasks.

Mainframe: A mainframe is a very large computer, which can process a lot of information simultaneously. It can also store huge amount of data inside. This is generally used in Big Corporate companies, Banks and Railways. A number of terminals (Keyboard and Screen) are attached to the mainframe to do jobs by a number of people.

Mini/Midi Computers: Mini and Midi computers are mid range computers between Mainframe and Personal Computers. Many terminals can be attached to this also, but the storage and processing capacity are less compared to mainframes.

Printer: A printer is an output device that gives you a hard copy (printed copy) of information from your computer. You can get the letters printed on a paper. Depending on the use and technology, printers are classified into many categories described as follows:

  1. Deskjet /Inkjet Printer: This is a portable printer that sprays ink on the paper through fine holes on the print head. It is a low cost printer and gives beautiful output. Most people use these printers as their personal printer.
  2. Dot Matrix Printer: A dot matrix printer uses needles arranged vertically on the print head. When the needle strikes on a printing ribbon (source of ink), it makes dots on paper arranged in the shape of characters you need.
  3. Line Printer: Line printers are very fast printers that could print one line at a time. These are used in large accounting firms and banks to print a huge amount of data.
  4. Laser Printer: A laser printer uses laser beam in printing. It gives high quality printouts. Laser printers are expensive compared to Dot Matrix and Desk jet printers.

Plotter: A Plotter is a device used to draw maps and diagrams.

Scanner: It is used to scan images of documents and photographs and convert into electronic form. By using a scanner you can scan your photograph and other documents and store in a computer. Those stored documents / photos can be sent through emails to the addresses stored in a PC.

Modem: A modem is a Modulation-Demodulation device. It converts digital signals from computers into analog (varying currents) signals and vice versa. It is used in telephonic applications, to send and receive FAX, while connected to Internet, etc.

Storage Devices: Storage devices are used to store data in a computer. There are different types of storage devices. They are:

  1. Hard Disk: A Hard disk is the most commonly used storage device, because it is very fast and can store a large amount of data.
  2. Floppy Disk: A floppy disk is a small storage device, generally used to store small amount of data and sent to different computers. This is the most economic storage device, which can be carried in our pocket.
  3. CDROM: A CDROM is a Compact Disk Read Only Memory that can contain large amount of data. It is the most reliable data source. You can only read its contents, you cannot write data onto it. However, compact disks are available with writing capability also. They are known as CDWORM (Write Once Read Many). Data can be written to it only once. Multiple write and erasable Compact Disks are also recently introduced.
  4. Magnetic Tapes: These are tapes, which looks similar to the audio and videocassettes. They can store large quantity of data like Hard disks, but it takes a lot of time to store and retrieve data. They used for archiving (permanent backup copy) data.

Memory: Memory is the temporary storage unit used by CPU. Memory stores and retrieves data faster than any other storage device. But data stored in memory will be lost when the computer is switched off. Depending on the method of storing, memory is stored into two groups. They are Random Access Memory (RAM) and Read Only Memory (ROM). The RAM is used to load pre-stored programs and operating systems while the CPU process information. CPU can write and erase information in RAM. ROM usually contains read only programs required for POST (Power On Self Test). It cannot be erased and the contents of program will be retained, even when the power is off.

CPU (Central Processing Unit): This is the main processing part of a computer. It is a Very Large Scale Integrated Circuit called Microprocessor. The names of most commonly used Microprocessors are Intel Pentium, Pentium Celeron, Pentium II and Pentium II processors.

Hardware: Computer Hardware is an electronic component like CPU, Monitor, and Keyboard that makes the computer.

Software: The software is a collection of programs written by a programmer in the language computer can understand. For example, Microsoft Office, Microsoft Windows, Lotus Smart Suite, Netscape Navigator, are some of the commonly used software.

Operating System: Operating System is software that is loaded initially into a computer. The OS translates the instructions from other software into machine language that CPU can understand. When a computer is powered on, it must load an operating system into its memory before it allows us to work. The process of loading the operating system into memory is called booting the system. The well-known operating systems are MSDOS, Microsoft Windows 95, etc.