Classes of computers
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Computers can be classified, or typed, many ways. Some common classifications are summarized below. For others see Category:Classes of computers.
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[edit] Micro computers
Micro computers are the most common type of computers in existence today, whether at work in school or on the desk at home. The term "Micro computer" was introduced with the advent of single chip large scale integrated circuit computer processors. The term "micro computer" itself, is now practically an anachronism.
These computers include:
Personal digital assistants (more commonly known as PDA's)
[edit] Minicomputers
The term "Mini computer" was coined at the time when most computers were cabinet sized like Mainframe Computers. Mini computers were much smaller, less powerful, and much less expensive than Mainframe Computers. The first Mini computers generally only performed one task at a time, while bigger computers ran multi-tasking operating systems, and served multiple users. Mini computers were typified by small word sizes such as 8 or 16 bits whereas larger machines had larger word sizes.
[edit] Mainframe Computers
The term Mainframe computer was created to distinguish the traditional, large, institutional computer intended to service multiple users from the smaller, single user machines. These computers are capable of handling and processing very large amounts of data easily and quickly. A mainframe speed is so fast that it is measured in millions of tasks per milliseconds (MTM). While other computers became smaller, Mainframe computers stayed large to maintain the ever growing memory capacity and speed. Mainframe computers are used in large institutions such as government, banks and large corporations. These institutions were early adopters of computer use, long before personal computers were available to individuals. "Mainframe" often refers to computers compatible with the computer architectures established in the 1960s. Thus, the origin of the architecture also affects the classification, not just processing power.
[edit] Servers
Server usually refer to a computer that is dedicated to the task of storing and retrieving large amounts of data. For example, a large computer dedicated to a database may be called a "database server". "File servers" manage a large collection of computer files. "Web servers" process web pages and web applications. This tends to distinguish them from "mainframes", which were generally intended to handle a variety of tasks. In some instances, a computer that was once considered a mainframe, is given the role of Server. This is because the actual data processing is taken over by individual personal computers. Many smaller servers are actually personal computers that have been dedicated to the task of storing data for other personal computers. In other instances, many small computers (essentially specialised personal computers) are designed to work in concert as a single server.
[edit] Workstation
Workstations are computers that are intended to serve one user and may contain special hardware enhancements not found on a personal computer. They run operating systems that are normally associated with mainframe computers, usually one of the variants of the UNIX operating system.
[edit] Portable Data Entry Terminals
Portable data entry terminals (more commonly known as PDET's) are handheld devices that are used to record or capture data away from the mainframe computer that they are linked to. Examples of PEDT's include
Barcode readers Gas Meter
Optical mark readers (as in lottery ticket readers)
[edit] Embedded computer systems
Embedded computers are general purpose CPUs that are a part of a machine or device. This computer runs a program that is stored in read only memory (ROM) and is only intended to operate a specific machine or device. Practically all consumer electronics (including electric toothbrushes), automobiles and industrial machines contain embedded computers today. They are intended to operate this single machine or a single function of that machine. Embedded systems are typically required to operate continuously without being reset or rebooted, and once employed in their task the software usually cannot be modified. An automobile may contain a number of Embedded systems; however, a washing machine and a DVD player would contain only one. The CPUs used are slower and less expensive than those found in a personal computer, but they generally only have to conduct a single function.
[edit] Supercomputer
A supercomputer is focused on performing one task involving intense numerical calculations such as weather forecasting and solving scientific problems. The distinction between supercomputers and mainframes can be difficult to define at times. Supercomputers tend to be custom built and focus on processing power to do one task. Mainframes, while providing a lot of processing power, focus more on data throughput and generally perform many datahandling operations involving minor computations.
