A microcomputer is a computer which uses a microprocessor for its central processing unit. Computers, in their early stages, were unlike what they are today. Instead of occupying a desk-top, they needed large halls to house. This was because they used large and bulky vacuum tubes or electronic valves. In the late sixties, with the advent of semiconductor materials like germanium and silicon, small, effective, cheaper and robust micro-devices like the transistors and the chip were developed.
A typical chip, of the size of a thumbnail, contained a number of transistors, diodes, varistors, etc. This chip not only reduced the size of the computers but also enhanced the power of the computer to a great extent. This development of computers from a room size to pocket-size took place in different stages of integration and miniaturization of electronic components. These different stages of integration are popularly known as SSI, VLSI and ULSI (small-scale, very-large-scale and ultra-large-scale integration respectively) in the electronic industry.
A microcomputer consists of a microprocessor, input or output devices, memory unit and typical connecting links called system buses.
Many people transmit malicious viruses, mostly through e-mails. The virus is a small hidden program that deletes the data or destroys parts of the operating system, which controls the computer. The viruses then automatically go to other computers through e-mail addresses stored in our computer. Some protection is offered by the antivirus programs. The safest way to stop viruses entering your computer is not to open attachments from unknown senders, especially the ones with an unusual ‘subject’.
For reading on-screen texts the blind need a special reading line in Braille script. For this, the computer converts the text in electrical signals, which are then pressed upwards by the corresponding points in the reading line. The blind can then feel the Braille. Or the text can be read aloud to them by a special speech program – they can also dictate texts in the same way. In this way, the visually challenged can also surf on the Internet. Pictures must always be accompanied by text; otherwise the blind cannot ‘read’ them.
In 1969, some American universities and research institutes needed more computing power, and connected their computers with one another. Later, more and more computers got connected, giving rise to a worldwide network called the Internet. On the other hand, the ‘WWW’ – and the sending of e-mails – is a service, which is offered within the Internet. It is a worldwide association of information pages connected with one another called the ‘World Wide Web’. The basic requirement for searching in the WWW or for sending e-mails is access to the Internet, maybe through a telephone line. Surfing, i.e., searching for information, in the WWW is not possible without a special program called a browser which understands the language of the Web. The address of the website we want to look at is typed in the browser. For instance, the website 
The heart of computers is the ‘CPU’, the central processing unit. It controls all the processes in the computer. Everything that happens is broken down in simple datasets. Computers know only two switching states, which are expressed by numbers: 1 stands for ‘power on’, 0 for ‘power off’. All the data stored in the computer is encoded with different combinations of both these digits, the binary code – ‘binary’ means ‘two’. For instance, when we press ‘a’ on the computer, it is then converted into the number sequence 1100001: The last position stands for 1, the second last for 2, the third for 4, followed by 8, 16, 32, 64, and so on. The positions occupied by ‘1’ are counted, for the number sequence for ‘a’, it will be 1+32+64= 97. The code for ‘a’ is, therefore, 97. All data can be coded in this way – computers, therefore, actually calculate only with ‘1’ and ‘0’.
The word ‘computer’ comes from the phrase ‘to compute’, or ‘to calculate’. Tools that help calculations, such as the abacus, have been around for the past 3000 years, but electronic computers that can perform complicated tasks at lightning speed appeared only about 70 year ago. Today, the world can no longer be imagined without computers. We enter commands with the help of keyboards and don’t stop to wonder at phrases like ‘open a window’ with the ‘mouse’. The world of ‘bits and bytes’ is also open to the blind. One has to be careful while downloading information from the Internet because malicious viruses can also be downloaded.
We need access to the Internet to send an e-mail. We can get the access by paying money to an internet service provider. In addition, one needs the email address of the receiver. The e-mail starts its journey when ‘Send’ is pressed from the sender’s email account. The e-mail then goes to the service provider, who sends from one ‘node’ to another, before it reaches its destination. It may happen that an e-mail sent from Berlin, goes to USA, then to India, and finally reaches your neighbour.
LAN is the short form of Local Area Network. It allows the linking together of several computers within a building. This interconnection of various computer terminals located in close proximity such as an industrial complex, an office building and a university campus enables each terminal to interact with any other. LAN is, therefore, a multi-user system. Not only is the exchange of data among the various linked up computers made possible by LAN but resources from a large computer can also be shared. LAN thus offers the most effective means of handling local automated tasks and data management.
A computer virus is a self-replicating computer program or a segment of code that inserts copies of itself into other programs, thus infecting them. As a result, the original programs cannot run smoothly, thereby totally disrupting the functioning of the computer.
Computer mouse is a device for manipulating figures on a computer screen without using a keyboard. It is an input mechanism that bears some resemblance to the animal. Computer operations often involve creating, selecting, or manipulating items on a screen. A computer mouse can perform these tasks by pointing or taking the cursor to the desired place, on the screen.
