Hardware is a comprehensive term for all of the physical parts of a computer, as distinguished from the data it contains or operates on, and the software that provides instructions for the hardware to accomplish tasks. The boundary between hardware and software is slightly blurry - firmware is software that is built-in to the 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, while others use expansion slots for graphics cards, network cards, or other I/O devices. The graphics card or sound card may employ a break out box to keep the analog parts away from the electromagnetic radiation inside the computer case. 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. 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. Computer case Main article: Computer case A stripped ATX case lying on its side. A computer case is the enclosure that contains the main components of a computer. Cases are usually constructed from steel or aluminum, although other materials such as wood and plastic have been used. Cases can come in many different sizes, or form factors. The size and shape of a computer case is usually determined by the form factor of the motherboard that it is designed to accommodate, since this is the largest and most central component of most computers. Consequently, personal computer form factors typically specify only the internal dimensions and layout of the case. Form factors for rack-mounted and blade servers may include precise external dimensions as well, since these cases must themselves fit in specific enclosures. Currently, the most popular form factor for desktop computers is ATX, although microATX and small form factors have become very popular for a variety of uses. Companies like Shuttle Inc. and AOpen have popularized small cases, for which FlexATX is the most common motherboard size. Power supply unit Main article: Power supply unit (computer) Computer power supply unit with top cover removed. The power supply unit converts general purpose electric current from the mains to direct current for the other components of the computer. The rated output capacity will be about 40% greater than the calculated system power consumption needs obtained by adding up all the system components. This protects against overloading the supply, and guards against performance degradation. Processor Main article: Central processing unit AMD Athlon 64 X2 CPU. The central processing unit, or CPU, is that part of a computer which executes software program instructions. In newer PCs the CPU is about a million transistors in one integrated circuit chip called the microprocessor. The microprocessor plugs into the motherboard. The chip generates so much heat that the PC builder is required to attach a special cooling device to its surface. Modern CPUs are equipped with a fan attached via heat sink. IBM PC compatible computers use an x86-compatible microprocessor. Intel, AMD, VIA Technologies or Transmeta manufacture them. Apple Macintosh computers were initially built with the Motorola 680x0 family of processors, then switched to the PowerPC series. In 2006 they switched to x86-compatible processors by Intel. Motherboard Main article: Motherboard A motherboard without processor, memory and extension cards, cables The motherboard, also referred to as system board or main board, is the primary circuit board within a personal computer. Other major system components plug directly onto or cable into the motherboard. A motherboard will contain a microprocessor, the CPU supporting circuitry (mostly integrated circuits) that provide the interface between memory and input/output peripheral circuits, main memory, and facilities for initial setup of the computer immediately after power-on (often called boot firmware or, in IBM PC compatible computers, a BIOS). In many portable and embedded personal computers, the motherboard houses nearly all of the PCs core components. Often a motherboard will also contain one or more peripheral buses and physical connectors for expansion purposes. Sometimes a secondary daughter board is connected to the motherboard to provide further expandability or to satisfy space constraints. Main memory
Posted on: Mon, 03 Feb 2014 09:29:11 +0000
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