Types of computer systems The mainframe is the most powerful type of computer. The central system is a large server connected to hundreds of terminals over the network. Mainframes are used for large-scale computing in banks, large companies and universities. A desktop PC has its own processor, monitor and keyboard. It is used as a personal computer at home or as a workplace for group work. Typical examples are IBM PC and Apple Macintosh. A laptop is a lightweight computer that you can transported easily. Modern laptops have a TFT display screen that produces very clear images. Instead of a mouse, they have a touchpad built into the keyboard, they offer a variety of connection options: USB, ports for connecting peripheral devices, memory card slots, etc. A tablet computer looks like a book with a liquid crystal screen on which you can write with a special digital pen. Your handwriting can be recognized and converted into editable text. It is mobile and versatile. A personal digital assistant or PDA is a tiny computer which can be held in one hand. To enter, you type text on a small keyboard or use a stylus - a special pen used with a touch screen to select elements, draw pictures, etc. Some PDAs recognize spoken words using voice recognition software. The wearable computer runs on batteries and is worn on the user's body, for example, on a belt, backpack or vest. Some devices are equipped with wireless a modem, a small keyboard and a screen: others are activated by voice.
