Desktop computer

A desktop computer is a personal computer made for use on a desk in an office or home and is distinguished from portable computers such as laptops or PDAs. Desktop computers are also known as microcomputers. There are four types of desktop computers: home computers, or personal computers; workstations, Internet servers, and special communications computers.

Desktops are currently the most affordable computers and ubiquitous in businesses, schools, and households; they are used for performing office tasks, organizing digital photos, video editing, and Internet access. Nearly all desktop computers are modular, with components that can easily be replaced or upgraded.

Desktop computers come in a variety of case styles ranging from large vertical towers to small form factor models that can be tucked behind an LCD monitor.

Desktop computers are commonly connected to a power strip.

History


Desktop computers were widely produced throughout the late 1970s and 1980s. One class that Hewlett Packard first introduced as a high-end programmable calculator was the HP 9830 which integrated a keyboard, ROM based HP BASIC OS, cassette drive, and 32 character LED display and a fast printer into one desktop unit, and could drive a graphics plotter. The business unit in Loveland, Colorado that produced the series was called HP's "Desktop Computer Division". The IBM 5100, Wang 2200, and Tektronix 4051 were similar desktop sized integrated computers, some of which evolved into scientific workstations or small business computers.

Modular boxes that needed external storage and terminals were named "microcomputers" to differentiate them from the mainframe and minicomputers that were traditionally available for sale by the major computer companies at the time. In 1975 the MITS Altair 8800 became the first pre-assembled desktop computer available on the market. However, due to the computer's design being geared more towards the hobbyist market the appeal of the machine was limited.

1977 saw the near-simultaneous release in the U.S. of three computers that equally deserve mention as the forerunners of today's desktop computer: the Apple II, the Commodore PET. and the Tandy TRS-80 computer. Each of these machines would be considered crude by today's standards; the TRS-80, for example, comprised a green phosphor 12" screen, an expansion box with 4 kilobytes of memory, a keyboard and a cassette recorder. It retailed for around £695. These computers also integrated display memory, keyboard, and sometimes storage and CRT into one unit.

Through the 1980s the desktop computer became more and more commonplace in society. Sales boomed as a wide spectrum of users, from the largest corporation down to the individual at home, found exciting new uses for the machines. However, it was not until the internet explosion in the mid-1990s that the desktop computer became nearly ubiquitous in our modern era.

Hardware

An exploded view of a modern desktop computer:

• Display
  
• Motherboard
  
• CPU (Microprocessor)
  
• Primary storage (RAM)
  
• Expansion cards
  
• Power supply
  
• Optical disc drive (ODD)
  
• Secondary storage (HDD)
  
• Keyboard
  
• Mouse
  

The hardware in a desktop computer is modular, making it easy for someone with intermediate knowledge of a computer to modify one. Desktop computers are generally more affordable than notebook computers. This is because no extra effort is needed to miniaturize the components, or to manufacture components that use up less power.

Components

• Fan - cools the computer. These are present on most computers. There are often multiple, one to cool the processor(see below), one in the power supply, and possibly additional ones for the graphics card and general cooling.
  
• Motherboard (a.k.a. Mainboard) - links all of the components together and routes data.
  
• HDD (Hard Disk Drive) - location where all information can be stored even when power is off.
  
• ODD (Optical Disc Drive) - reads most or all types of CDs and/or DVDs.
  
• Processor - The main brain of the computer.
  
• CPU Cooler - cools the processing unit. Typically a fan combined with a heatsink.
  
• RAM - short-term data storage, which works only when power is on.
  
• Graphics card - codes video output and delivers to monitor.
  
• Physics card - performs physics computations in some modern games.
  
• Sound card - codes sound output and delivers to speakers.
  
• Speakers - deliver sound.
  
• Modem - used to access data via a telephone line (dial-up connection). Used to access BBS and the Internet.
  
• Network card - allows the computer to be linked to a computer network where it can communicate with other computers. Also used as a means of accessing the Internet via a broadband connection.
  
• Computer PSU (Power Supply Unit) - A device that provides power to the rest of the computer parts.
  
• FDD (Floppy Disk Drive) - Reads and Writes floppy disks. Although largely supplanted by CDs and Flash Drives, is still common on many systems, and may be required during set-up on certain operating systems.
  
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Ports

All desktop computers have ports which are used to plug external devices into the computer such as monitors, keyboards, printers and scanners.
USB - Used for the majority of peripherals. Designed to be a universal connector, to be compatible with any device.
Ethernet - Used for networking and broadband Internet connections.
Modem - Used for data access via a telephone line (eg. dial-up Internet connections). Slowly being replaced by broadband connections as dial-up becomes an obsolete technology.
Headphone jack - Used for connecting sound devices. (USB can also be used)
Serial - Used for connecting any device that uses a serial connector. These are being replaced by USB.
Parallel - Used for connecting any device that uses a parallel connector. These are being replaced by USB.
PS/2 - Used for computer mice and keyboards (These are being replaced by USB)
Video (VGA) - Used for connecting a monitor / projector with analog signal.
Digital Video Interface (DVI) - Used for connecting a monitor, but keeps in the signal in digital format. Usually used for LCD displays.
Power - Used for connecting the power lead.
FireWire/IEEE 1394 - Used for connecting external hard drives and camcorders.
Card reader - used to read flash memory cards belonging to digital cameras, mobile phones, music players etc.

All-in-one

All-in-one computers are desktop computers that combine the monitor into the same case as the CPU. The term, "all-in-one" was initially associated with Digital Equipment Corporation's VAX "all-in-one" software which provided a common menu to choose: email, spreadsheet, database, file system, etc. The "mouse" had not been invented yet so everything was driven by the keyboard. The original Macintosh introduced in 1984 by Apple Computer was one of the first all-in-one computers, In 1998 Apple released the iMac which was also an all-in-one computer. These types of desktop computers save desk space, but are limited when it comes to expansion to improve their capabilities. Some PC and refrigerator manufacturers have even included full featured PCs and monitors in refrigerators which could be considered all-in-one.