Classification of Computers
These days, computers are available in may sizes and types. Some computers can fir in the palm of the hand, and some can occupy the entire room. Based on physical size, performance and application areas, computers can be divided into following four categories:
1. Micro computers
2. Mini computers
3. Mainframe computers
4. Super computers
1. Micro computers
i. Microcomputers are small, low cost and single user digital computer.
ii. They consist of CPU, input unit, output unit, storage unit and the software.
iii. Originally, these were designed for individual users only, but nowadays they have become powerful tools for many businesses that, when networked together, can serve more than one user.
iv. Microcomputers include laptops, desktops, tablet, Handheld computer or Personal Digital Assistant (PDA). Smart phones.
v. IBM PC based on Pentium microprocessor and Apple Macintosh are some examples of microcomputers.
2. Mini computers
i. Mini computers are general purpose computers, smaller that mainframe and give computing power without adding the prohibitive expenses associated with larger systems.
ii. Mini computer is a small digital computer, which normally is bale to process and store less daa than a mainframe but more than a micro computer, while doing so less rapidly than a mainframe but more rapidly than a microcomputer.
iii. It is about about the size of a two drawer filing cabinet.
iv. It is generally used as desktop devices that are often connected to a mainframe in order to perform the auxiliary operations.
v. The mini computer’s size prevents it from being portable but it can be moved more easily than a mainframe.
vi. Micro computers can support 4-200 users simultaneously.
vii. Mini computers are well adapted for functions such as accounting, word processing, data base management, statistical packages for social sciences, Computer Aided Design (CAD) and Numerical Analysis etc.
viii. Some of the widely used mini computers are PDP 11, IBM (8000 series) and VAX 7500.
3. Mainframe computers
i. These are multi-user, multi-programming and high performance computers.
ii. They operate at a very high speed, have very large storage capacity and can handle he workload of many users.
iii. Mainframes processes data at several million instructions per second (MIPS). More than 1,000 remote workstations can be accommodated by a typical mainframe computer.
iv. Mainframe allows its users to maintain large information storage at a centralized location and be able to access and process this data from different computers located at different locations. The technique that allows many people at terminals to access the same computer at one time is called time sharing.
v. It is typically used by large businesses and for scientific purposes. Mainframes are used by banks and many businesses to update inventory etc.
vi. Example of mainframe computers are IBM’s ES000, VAX 8000 and CDC 6600.
4. Super Computers
i. They are the fastest and the most expensive machines.
ii. They have high processing speed compared to other computers. The speed of a super computer is generally measured in FLOPS (Floating Point Operations Per Second).Any computer below one gigaflop/sec is not considered a super computer.
iii. It contains a number of C.P.Us that operate parallel to make it faster. Its processing speed lies in the range of 400-10,000 MFLOPS (Millions Floating Point Operation Per Second).
iv. Typically supercomputers are used to solve multi-variant mathematical problems of existent physical processes, such as aerodynamics, metrology and plasma physics, processing of geological data, genetic coding and collecting and processing of weather data. These are also required by the military strategies to stimulate defense scenarios. Cinematic specialists use them to produce sophisticated movie animations. Scientists build complex models and simulate them in a super computer. The largest commercial uses of super computers are in the entertainment/advertising industry.
v. Super computers recognize the largest word lengths of 64 bits or mire. They calculate at rates upto 1.2 billion instructions per second. They can take input from over 10,000 individual workstations.
vi. CRAY-3, Cyber 205, and PARAM are some well known super computers.
