G azərbaycan respublikasi təHSİl naziRLİYİ azərbaycan texniKİ universiteti M. M. QƏNDİLova e. Q. İsmayilova

UNIT III

Give me but one firm spot on

which to stand I will move the earth

Archimedes

TYPES OF COMPUTERS

As we have some knowledge what a computer is, we can consider the types of computers used in information systems today. In terms of size computers fit broadly into three types – mainframes, minicomputers, and microcomputers, which are also called personal computers.
A mainframe is a very large, expensive computer (usually selling for well over $1 million) that requires a special support staff and a special physical environment (for example, air conditioning). Mainframes are usually housed in a computer center and are generally used in large business, government, or academic institutions where they support multiple users (usually more than 100 at one time) and can handle multiple processing tasks concurrently. This means that a mainframe can, for example, do a statistical analysis for one user, print a report for a second user, and process student grades concurrently.
Users access a mainframe on computer terminals that interface with the computer. These terminals are usually composed of a keyboard for entering data and instructions and a display screen for viewing the work and any resulting output. They usually do not have their own computing capabilities.




A subset of mainframes is supercomputers, or “monsters,” which are the biggest and fastest computers in use today. These very large computers are used almost exclusively for research projects that require extremely high-speed processing and large storage capacities.

At the other extreme in term of size are personal computers (PC’s), which are small, one-user computer. They are relatively inexpensive to purchase and do not require a special environment or special user knowledge. These computers fit on a desktop and are sometimes referred to as desktop computers.




Somewhere between a mainframe and a personal computer is the mini-computer which is used by organizations that need more processing power than is available with personal computers, less than a mainframe offers. A mini-computer can support multiple users and may have some support staff.
A special type of terminal is a workstation, a high-performance, single-user device that has characteristics of both a stand-alone PC and a terminal. Like PCs, workstations have built-in computing power. However, workstations differ from PCs in that they can carry out multiple tasks concurrently.