USING A COMPUTER

Until now, we have talked about the computer more as a physical device: what it's made of, what's inside it, what additional devices can be connected, etc. All of this is called the hardware or hardware of the computer. We have been introduced to many devices that perform sometimes quite complex actions. But the hardware of a computer is not the whole computer, or even the most important part of it. A computer is not a TV set that you turn on, set the right programme and watch to your heart's content. A computer has a different purpose - to do not just one job, but many different jobs, to help people do intellectual work.

A computer only performs actions when it has instructions in its memory on what to do and how to do it, i.e. when it has programs installed that perform the relevant actions. Without programs, a computer can do little, or indeed nothing, without doing anything. It needs instructions on what to do. This means that a person has to prepare the instructions and store them in the computer's memory - only then will the computer do the action. These instructions must be written in a language that the computer understands, according to agreed rules - a programming language. This is why the instructions themselves are called programmes.

In the last section, we looked at how a computer carries out machine instructions - again, programmes. This means that when we want a computer to solve a problem, we have to use a program to solve the problem: we have to install the necessary program on the computer, or, in the simplest case, we have to write it into the computer's memory. The solutions (algorithms) differ from one problem to another. This is why different programs are developed. They are constantly updated, improved and changed. Programmes are therefore the most important components of a computer and are the basis for all computer work.

The totality of the programs used to control a computer or to process the information it contains is called software. Software can be divided into two main groups: operating systems and applications.

You probably know yourself how many different kinds of applications there are, and you have seen or at least heard of dozens of games alone (which are also nothing more than applications). It takes a long time to write a good application - sometimes months, sometimes years. But once a good program is written, it can be used by many people for a long time (as long as the problem is relevant). This is why most professional software products are considered commodities - you have to buy them to use them.

We could compare software to recipes for cooking. After all, we don't often create new dishes ourselves - we usually take recipes invented by others and follow them more or less exactly as they say. Similarly with a computer: we give it a program and ask it to do something. The actions depend on the type of program - the computer does exactly what it says: plays a game (if we have a game program), edits text (if we have a text editor), draws (if we have a graphics editor), teaches us a foreign language (if we have a language learning program), etc. This means that we use game programmes to play, we process (edit) text with word processing systems or, in other words, text editors, we write music with music editors, we learn biology with biology learning programmes, etc.

However, there are jobs (actions) that a computer does all the time. These include writing programs to and from computer disks to storage media and vice versa, instructing which program to run, where to get data from, where to put the results. Finally, something has to shape the image on the screen (letter codes are represented by dots), keyboard keystrokes have to be turned into characters, and the mouse on the tray has to be simulated by a cursor running across the screen. Of course, it is possible to make a computer processor that can do these operations itself, for example, by using its commands to shape the image on the screen. But then only one kind of display would be suitable for such a computer. If the display were to be changed (e.g. to a different size, different resolution), the computer processor would have to be changed as well. It is therefore better to write separate programs for such work. Then, if you change the display, printer, or other device, all you have to do is to add another program to the computer that is suitable for that device, and the computer will work. In fact, this is how it works.

The programs that directly control the actions of the computer and link human work to the actions of the computer, together with the data needed for those programs, are combined into a coherent whole called an operating system.

The operating system is the most important piece of software that organises the computer and all its devices. The operating system, together with some of the other programs that run the computer, is often referred to as system software.

The operating system starts when the computer is switched on and is the coordinator of its hardware components and all other programs.