Categories of Computer

Four categories of computer 

Micro computer 

Micro computers are sometimes called laptop computers," "personal computers" or business microcomputers”. Major micro computer manufacturers include Apple, AT&T, Commodore, Compaq, IBM and Tandy/Radio shack. The most important characteristic of a microcomputer is its low price. However extended memory and hard disks can make the cost high.

A typical microcomputer is operated by a single person- hence the term personal computer or PC. However, most micro computers can operate either as independent computers in "stand alone mode" or an intelligent terminals in "network mode". In stand alone, the microcomputer runs software programs that process data independently. In network mode, the micro enables user to communicate with larger computers and also with each other.

Mini computer

Mini computers are typically multi-user systems, sometimes supporting more than 500 online terminals. Generally, the proceeding speeds and related capabilities of minicomputers exceed those of microcomputers, and more peripheral devices can be attached to them.

Mini computers tends to have more sophisticated operating systems than microcomputers and can usually be programmed in a wider variety of programming languages.

Mainframe computers

Beyond mini, we have mainframes, which are fully configured computers intended for substantial, high volume data processing. Mainframe manufacturers include IBM, CDC etc. Mainframe computers have large primary memory, which usually exceed several millions characters. They have very powerful processors, which can process several million instructions per second. Substantial amount of peripherals can be attached to the computer. These computers can support · thousands of online terminals at once. Mainframe computers are purchased as host computers -i.e., computers that serve as central receiving and switching computer in regional and national computer networks.

Super computers

The largest mainframes are called super computers. They have huge primary memory (measured in hundreds of millions of locations) and the most advanced processing capabilities. Super computers are typically designed with state-of-art computer architecture, including unique cooling systems to dissipate internal heat buildup and the ability to execute programs instructions concurrently instead of sequentially. Prices of super computers can exceed lakhs. Customers include, the national weather service, oil companies, military and aerospace firms.