A stylized illustration of a tower personal computer

A desktop computer is a personal computer (PC) in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright. Most modern desktop computers have separate screens and keyboards.

Prior to the widespread use of microprocessors, a computer that could fit on a desk was considered remarkably small. Early personal computers, like the IBM PC, were "desktop" machines, with a horizontally-oriented computer case, usually intended to have the display screen placed on top to save space on the desktop. In modern usage the word "desktop" usually refers to tower cases that are in fact more often located on the floor under the desk than on a desk.

Technically speaking desktop and tower computers are two different styles of computer case that use desk space in varying ways.^{[original research?]} Cases intended for home theater PC systems are usually considered to be desktop cases in both senses, regardless of orientation and placement.^{[original research?]}

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History

A sophisticated programmable calculator, the HP 9830A was actually an early desktop computer with printer.

Early computers took the space of a room. Minicomputers generally fit into one or a few refrigerator sized racks. It was not until the 1970s when computers such as the HP 9800 series desktop computers(however the Programma 101 was earlier)^[1] were fully programmable computers that fit entirely on top of a desk. The first large calculators were introduced in 1971, leading to a model programmable inBASIC in 1972. They used a smaller version of a minicomputer design based on ROM memory and had small one-line LED alphanumeric displays. They could draw computer graphics with a plotter. The Wang 2200 of 1973 had a full-size cathode ray tube (CRT) and cassette tape storage. The IBM 5100 in 1975 had a small CRT display and could be programmed in BASIC and APL. These were generally expensive specialized computers sold for business or scientific uses. By the late 1970s and 1980s personal computers, such as the Apple II series and the IBM Personal Computer used standard processors to reduce cost to put a complete computer on top of a desk with a separate monitor. These would find uses in the home as well as in business and industry, and later incorporate graphic user interfaces and powerful networked operating systems such as Mac (Macintosh) and Windows.

[edit]All-in-one

All-in-one computers are desktop computers that combine the CPU and speaker into the same case as the monitor. Apple has manufactured several popular examples of all-in-one computers, such as theoriginal Macintosh of the mid-1980s and the iMac of the late 1990s and 2000s. Some older 8-bit computers, such as the Commodore PET 2001 or Kaypro II, also fit into this category. All-in-one PCs are typically more portable than other desktop PCs and many have been built with carrying handles integrated into the case. They can simply be unplugged and transported to a new location.

Like laptops, all-in-one desktop computers are characterized by a comparative lack of upgradeability or hardware customization, as internal hardware is often placed in the back of the visual display unit. Furthermore, in the case of the iMac line since 2002, the CPU and other internal hardware units are, more or less, permanently attached to the motherboard due to space constraints.

However, newer models of all-in-one computers have changed their approach to this issue. Many of the current manufacturers are using standard off-the-shelf components and are designing upgrade convenience into their products^{[citation needed]}.