A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator. In contrast, the batch processing or time-sharing models allowed larger, more expensive minicomputer and mainframe systems to be used by many people, usually at the same time. Large data processing systems require a full-time staff to operate efficiently. Consoles can also be considered personal computers.
Software applications for personal computers include, but are not limited to, word processing, spreadsheets, databases, Web browsers and e-mail clients, digital media playback, games, and myriad personal productivity and special-purpose software applications. Modern personal computers often have connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. Personal computers may be connected to a local area network (LAN), either by a cable or a wireless connection. A personal computer may be a desktop computer or a laptop, tablet, or a handheld PC.
While early PC owners usually had to write their own programs to do anything useful with the machines, today's users have access to a wide range of commercial software and free software, which is provided in ready-to-run or ready-to-compile form. Since the early 1990s, Microsoft software and Intel hardware have dominated much of the personal computer market, first with MS-DOS and then with the Wintel platform. Popular alternatives to Microsoft's Windows operating systems include Apple's Mac OS X and open-source Linux-based operating systems such as Ubuntu. AMD is the major alternative to Intel's central processing units. Applications and games for PCs are typically developed and distributed independently from the hardware or OS manufacturers, whereas software for many mobile phones and other portable systems is approved and distributed through a centralized online store.
Software applications for personal computers include, but are not limited to, word processing, spreadsheets, databases, Web browsers and e-mail clients, digital media playback, games, and myriad personal productivity and special-purpose software applications. Modern personal computers often have connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. Personal computers may be connected to a local area network (LAN), either by a cable or a wireless connection. A personal computer may be a desktop computer or a laptop, tablet, or a handheld PC.
While early PC owners usually had to write their own programs to do anything useful with the machines, today's users have access to a wide range of commercial software and free software, which is provided in ready-to-run or ready-to-compile form. Since the early 1990s, Microsoft software and Intel hardware have dominated much of the personal computer market, first with MS-DOS and then with the Wintel platform. Popular alternatives to Microsoft's Windows operating systems include Apple's Mac OS X and open-source Linux-based operating systems such as Ubuntu. AMD is the major alternative to Intel's central processing units. Applications and games for PCs are typically developed and distributed independently from the hardware or OS manufacturers, whereas software for many mobile phones and other portable systems is approved and distributed through a centralized online store.
In July and August 2011, marketing businesses and journalists began to talk about the 'Post-PC Era', in which the desktop form factor was being replaced with more portable computing such as netbooks, Tablet PCs, and smartphones
Hardware
Mass-market consumer computers use highly standardized components and so are simple for an end user to assemble into a working system. A typical desktop computer consists of a computer case which holds the power supply, motherboard, hard disk and often an optical disc drive. External devices such as a computer monitor or visual display unit, keyboard, and a pointing device are usually found in a personal computer.
The motherboard connects all processor, memory and peripheral devices together. The RAM, graphics card and processor are mounted directly onto the motherboard. The central processing unit microprocessor chip plugs into a socket. Expansion memory plugs into memory sockets. Some motherboards have the video display adapter, sound and other peripherals integrated onto the motherboard. Others use expansion slots for graphics cards, network cards, or other I/O devices. Disk drives for mass storage are connected to the mother board with a cable, and to the power supply through another cable. Usually disk drives are mounted in the same case as the motherboard; formerly, expansion chassis were made for additional disk storage.
The graphics and sound card can have a break out box to keep the analog parts away from the electromagnetic radiation inside the computer case. For really large amounts of data, a tape drive can be used or (extra) hard disks can be put together in an external case.
The keyboard and the mouse are external devices plugged into the computer through connectors on an I/O panel on the back of the computer. The monitor is also connected to the I/O panel, either through an onboard port on the motherboard, or a port on the graphics card.
The hardware capabilities of personal computers can sometimes be extended by the addition of expansion cards connected via an expansion bus. Some standard peripheral buses often used for adding expansion cards in personal computers as of 2005 are PCI, AGP (a high-speed PCI bus dedicated to graphics adapters), and PCI Express. Most personal computers as of 2005 have multiple physical PCI expansion slots. Many also include an AGP bus and expansion slot or a PCI Express bus and one or more expansion slots, but few PCs contain both buses.
Toxic chemicals, such as lead and mercury, are found in certain pieces of PC hardware. Lead is found in the Cathode ray tube (CRT), which is located inside the monitor, as well as in the Printed circuit board. While daily PC users are not exposed to these toxic elements, danger arises in computer recycling, and thus stems the controversy of electronic waste (e-Waste). The process of computer recycling involves workers responsible for manually breaking down computers, which leads to inevitable exposure to these toxic chemicals and serious health issues. Lead is known to cause damage to the central nervous system, kidneys, and slow down child brain development. Mercury, another toxic element found in PCs, is located in the screen's fluorescent lamp, laser light generators in the optical disk drive, and in mercury batteries in the circuit board and expansion cards. Even the smallest amount of mercury, if it is inhaled or digested can cause serious brain damage. Other chemicals found in PCs are cadmium, chromium, Polyvinyl chloride (PVC), and barium, which are also found in the motherboard and other crucial pieces of the computer. In each individual computer, about 17% of the computer is lead, copper, zinc, mercury, and cadmium, 23% is plastic (which usually gets burned and causes extreme air pollution), and 14% is Aluminium and 20% is Iron (the last two do not cause extreme health risks, however they are natural elements and do not decompose, which means they continue to take up space unless they are recycled into new computers). Although there is not a huge amount of these hazardous chemicals in each individual computer, even the smallest amount of lead or mercury can ruin a community’s drinking water, or cause serious brain damage.
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An exploded view of a modern personal computer and peripherals
1.Scanner2.CPU (Microprocessor)
3.Primary storage (RAM)
4.Expansion cards (graphics cards, etc.)
5.Power supply
6.Optical disc drive
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