A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers were designed to lie 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; the type of computers most commonly used were minicomputers, which were themselves desk-sized. Early personal computers, like the IBM PC, were enclosed in "desktop" cases, horizontally oriented to have the display screen placed on top, thus saving space on the user's actual desk. Over the course of the 1990s, desktop cases gradually became less common than the more-accessible tower cases that may be located on the floor under the desk rather than on a desk.
Early computers took up the space of a whole 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 became fully programmable computers that fit entirely on top of a desk. The very first large "programmable calculators/computers" (machines lacking keyboards for text input) were marketed in the second half of the 1960s, starting with Programma 101 (1965) and HP 9100 (1968). More desktop models were introduced in 1971, leading to a model programmable in BASIC in 1972. This one used a smaller version of a minicomputer design based on read-only memory (ROM) and had small one-line LED alphanumeric displays. They could draw computer graphics with a plotter.
Throughout the 1980s and 1990s desktop computers became the type in predominant use through the IBM PC and its clones, as well as the Apple Macintosh. Home computers are also often categorized under the desktop umbrella.
Recent reports in 2013 have shown a sharp decline in PC sales, this includes Windows based and Apple desktops.Reason for the decline is thought to be increased power and applications of smartphones and Tablet PC's. While most people exclusively use their computing device for social media and casual gaming, the requirement for a large desktop PC is declining. Also, decades of development means that most people already own desktop computers that meet their needs and have no need of buying a new one merely to keep pace with advancing technology.
An all-in-one PC integrates the system's internal components into the same case as the display, allowing for easier portability and a smaller footprint, especially on designs using flat panel displays. Some recent all-in-one models also include touchscreen displays.
Apple has manufactured several popular examples of all-in-one computers, such as the original Macintosh of the mid-1980s and the iMac of the late 1990s and 2000s. This form factor was popular during the early 1980s for computers intended for professional use such as the Kaypro II, Osborne 1, TRS-80 Model II and Compaq Portable. Many manufacturers of home computers like Commodore and Atari included the computer's motherboard into the same enclosure as the keyboard; these systems were most often connected to a television set for display.
Like laptops, some all-in-one desktop computers are characterized by an inability to customize or upgrade internal components, as the systems' cases do not provide easy access except through panels which only expose connectors for RAM or storage device upgrades. 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.
