A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise resource planning, and large-scale transaction processing. A mainframe computer is large but not as large as a supercomputer and has more processing power than some other classes of computers, such as minicomputers, servers, workstations, and personal computers. Most large-scale computer-system architectures were established in the 1960s, but they continue to evolve. Mainframe computers are often used as servers.
A minicomputer, or colloquially mini, is a type of smaller general-purpose computer developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, The New York Times suggested a consensus definition of a minicomputer as a machine costing less than US$25,000, with an input-output device such as a teleprinter and at least four thousand words of memory, that is capable of running programs in a higher level language, such as Fortran or BASIC.
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PCB). Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors. The predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive. Many microcomputers are also personal computers. An early use of the term "personal computer" in 1962 predates microprocessor-based designs. (See "Personal Computer: Computers at Companies" reference below). A "microcomputer" used as an embedded control system may have no human-readable input and output devices. "Personal computer" may be used generically or may denote an IBM PC compatible machine.
A desktop computer is a personal computer designed for regular use at a stationary location on or near a desk due to its size and power requirements. The most common configuration has a case that houses the power supply, motherboard, disk storage ; a keyboard and mouse for input; and a monitor, speakers, and, often, a printer for output. The case may be oriented horizontally or vertically and placed either underneath, beside, or on top of a desk.
A superminicomputer, colloquially supermini, is a high-end minicomputer. The term is used to distinguish the emerging 32-bit architecture midrange computers introduced in the mid to late 1970s from the classical 16-bit systems that preceded them. The development of these computers was driven by the need of applications to address larger memory. The term midicomputer had been used earlier to refer to these systems. Virtual memory was often an additional criteria that was considered for inclusion in this class of system. The computational speed of these machines was significantly greater than the 16-bit minicomputers and approached the performance of small mainframe computers. The name has at times been described as a "frivolous" term created by "marketeers" that lacks a specific definition. Describing a class of system has historically been seen as problematic: "In the computer kingdom, taxonomic classification of equipment is more of a black art than a science." There is some disagreement about which systems should be included in this class. The origin of the name is uncertain.
A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a clamshell form factor with a flat-panel screen on the inside of the upper lid and an alphanumeric keyboard and pointing device on the inside of the lower lid. Most of the computer's internal hardware is fitted inside the lower lid enclosure under the keyboard, although many modern laptops have a built-in webcam at the top of the screen, and some even feature a touchscreen display. In most cases, unlike tablet computers which run on mobile operating systems, laptops tend to run on desktop operating systems, which were originally developed for desktop computers.
A portable computer is a computer designed to be easily moved from one place to another, as opposed to those designed to remain stationary at a single location such as desktops and workstations. These computers usually include a display and keyboard that are directly connected to the main case, all sharing a single power plug together, much like later desktop computers called all-in-ones (AIO) that integrate the system's internal components into the same case as the display. In modern usage, a portable computer usually refers to a very light and compact personal computer such as a laptop, subnotebook or handheld PC, while touchscreen-based handheld ("palmtop") devices such as tablet, phablet and smartphone are called mobile devices instead.
The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid-state devices such as transistors and then integrated circuit (IC) chips. Around 1953 to 1959, discrete transistors started being considered sufficiently reliable and economical that they made further vacuum tube computers uncompetitive. Metal–oxide–semiconductor (MOS) large-scale integration (LSI) technology subsequently led to the development of semiconductor memory in the mid-to-late 1960s and then the microprocessor in the early 1970s. This led to primary computer memory moving away from magnetic-core memory devices to solid-state static and dynamic semiconductor memory, which greatly reduced the cost, size, and power consumption of computers. These advances led to the miniaturized personal computer (PC) in the 1970s, starting with home computers and desktop computers, followed by laptops and then mobile computers over the next several decades.
VEB Kombinat Robotron was the largest East German electronics manufacturer. It was headquartered in Dresden and employed 68,000 people in 1989. Its products included personal computers, SM EVM minicomputers, the ESER mainframe computers, various computer peripherals as well as microcomputers, radios, television sets and other items including cookie press Kleingebäckpresse Typ 102.
The IBM 5100 Portable Computer is one of the first portable computers, introduced in September 1975, six years before the IBM Personal Computer, and eight before the first successful IBM compatible portable computer, the Compaq Portable. It was the evolution of a prototype called the SCAMP that was developed at the IBM Palo Alto Scientific Center in 1973. Whether considered evolutionary from SCAMP or revolutionary, it still needed to be plugged into an electric socket.
A handheld personal computer (PC), typically built around either a clamshell form factor or a gaming form factor with a gamepad integrated for video games, is a mobile device that is significantly smaller than any standard personal computer (PC), but based on the same principles as PCs. The clamshell form factor is sometimes referred to as a palmtop computer, not to be confused with Palmtop PC which was a name used mainly by Hewlett-Packard.
Small form factor is a term used for desktop computers and for some of their components, chassis and motherboard, to indicate that they are designed in accordance with one of several standardized form factors intended to minimize the volume and footprint of a desktop computer compared to the standard ATX form factor.
Bell's law of computer classes formulated by Gordon Bell in 1972 describes how types of computing systems form, evolve and may eventually die out. New classes of computers create new applications resulting in new markets and new industries.
Midrange computers, or midrange systems, were a class of computer systems that fell in between mainframe computers and microcomputers.
The history of the personal computer as a mass-market consumer electronic device began with the microcomputer revolution of the 1970s. A personal computer is one intended for interactive individual use, as opposed to a mainframe computer where the end user's requests are filtered through operating staff, or a time-sharing system in which one large processor is shared by many individuals. After the development of the microprocessor, individual personal computers were low enough in cost that they eventually became affordable consumer goods. Early personal computers – generally called microcomputers – were sold often in electronic kit form and in limited numbers, and were of interest mostly to hobbyists and technicians.
A personal computer, usually referred to as a PC, is a computer designed for individual use. It is typically used for tasks such as word processing, internet browsing, email, multimedia playback, and gaming. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician. Unlike large, costly minicomputers and mainframes, time-sharing by many people at the same time is not used with personal computers. The term home computer has also been used, primarily in the late 1970s and 1980s. The advent of personal computers and the concurrent Digital Revolution have significantly affected the lives of people in all countries.
A mini PC is a small-sized, inexpensive, low-power, legacy-free desktop computer designed for basic tasks such as web browsing, accessing web-based applications, document processing, and audio/video playback.
Computer hardware comprises the physical parts of a computer, such as the central processing unit (CPU), random access memory (RAM), motherboard, computer data storage, graphics card, sound card, and computer case. It includes external devices such as a monitor, mouse, keyboard, and speakers.
The following outline is provided as an overview of and topical guide to computing:
Computers can be classified, or typed, in many ways. Some common classifications of computers are given below.
