A personal computer is made up of multiple physical components of computer hardware, upon which can be installed a system software called an operating system, and a multitude of software applications to perform the operator’s desired functions.
BIOS – The BIOS is a type of firmware used during the booting process (power-on startup) on IBM PC compatible computers. The BIOS firmware is built into PCs, and it is the first software they run when powered on. The name itself originates from the Basic Input/Output System used in the CP/M operating system in 1975. Originally proprietary to the IBM PC, the BIOS was reverse engineered by companies looking to create compatible systems and the interface of that original system serves as a de facto standard.
The fundamental purposes of the BIOS are to initialize and test the system hardware components, and to load a boot loader or an operating system from a mass memory device. The BIOS additionally provides an abstraction layer for the hardware, i.e. a consistent way for application programs and operating systems to interact with the keyboard, display, and other input/output devices. Variations in the system hardware are hidden by the BIOS from programs that use BIOS services instead of directly accessing the hardware. MS-DOS (PC DOS), which was the dominant PC operating system from the early 1980s until the mid 1990s, relied on BIOS services for disk, keyboard, and text display functions. MS Windows NT, Linux, and other protected mode operating systems in general ignore the abstraction layer provided by the BIOS and do not use it after loading, instead accessing the hardware components directly.
Every BIOS implementation is specifically designed to work with a particular computer or motherboard model, by interfacing with various devices that make up the complementary system chipset. Originally, BIOS firmware was stored in a ROM chip on the PC motherboard; in modern computer systems, the BIOS contents are stored on flash memory so it can be rewritten without removing the chip from the motherboard. This allows easy updates to the BIOS firmware so new features can be added or bugs can be fixed, but it also creates a possibility for the computer to become infected with BIOS rootkits.
Unified Extensible Firmware Interface (UEFI) was designed as a successor to BIOS, aiming to address its technical shortcomings. As of 2014, new PC hardware predominantly ships with UEFI firmwares.
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CPU – The central processing unit (CPU) is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the functions of the computer or other processing device. The central processing unit carries out each instruction of the program in sequence, to perform the basic arithmetical, logical, and input/output operations of the system. The term has been in use in the computer industry at least since the early 1960s. The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation remains much the same.
Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, computer. However, this costly method of designing custom CPUs for a particular application has largely given way to the development of mass-produced processors that are made for one or many purposes. This standardization trend generally began in the era of discrete transistor mainframes and minicomputers and has rapidly accelerated with the popularization of the integrated circuit (IC). The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of these digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in everything from automobiles to cell phones and children’s toys.
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Wikipedia: CPU
Wikipedia: CPU History – Intel
HARD DRIVE (HDD) – A hard disk drive (HDD) is a data storage device used for storing and retrieving digital information using rapidly rotating disks (platters) coated with magnetic material. An HDD retains its data even when powered off. Data is read in a random-access manner, meaning individual blocks of data can be stored or retrieved in any order rather than sequentially. An HDD consists of one or more rigid (“hard”) rapidly rotating disks (platters) with magnetic heads arranged on a moving actuator arm to read and write data to the surfaces.
Introduced by IBM in 1956, HDDs became the dominant secondary storage device for general-purpose computers by the early 1960s. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers. More than 200 companies have produced HDD units, though most current units are manufactured by Seagate, Toshiba and Western Digital. Worldwide disk storage revenues were US $32 billion in 2013, down 3% from 2012.
The primary characteristics of an HDD are its capacity and performance. Capacity is specified in unit prefixes corresponding to powers of 1000: a 1-terabyte (TB) drive has a capacity of 1,000 gigabytes (GB; where 1 gigabyte = 1 billion bytes). Typically, some of an HDD’s capacity is unavailable to the user because it is used by the file system and the computer operating system, and possibly inbuilt redundancy for error correction and recovery. Performance is specified by the time required to move the heads to a track or cylinder (average access time) plus the time it takes for the desired sector to move under the head (average latency, which is a function of the physical rotational speed in revolutions per minute), and finally the speed at which the data is transmitted (data rate).
The two most common form factors for modern HDDs are 3.5-inch in desktop computers and 2.5-inch in laptops. HDDs are connected to systems by standard interface cables such as SATA (Serial ATA), USB or SAS (Serial attached SCSI) cables.
As of 2014, the primary competing technology for secondary storage is flash memory in the form of solid-state drives (SSDs). HDDs are expected to remain the dominant medium for secondary storage due to predicted continuing advantages in recording capacity, price per unit of storage, write latency and product lifetime. However, SSDs are replacing HDDs where speed, power consumption and durability are more important considerations.
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Data Storage Device Timeline
Wikipedia: Hard Disk Drive
Wikipedia: Hard Disk Drive History
KEYBOARD – In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. Following the decline of punch cards and paper tape, interaction via teletype-style keyboards became the main input device for computers.
Despite the development of alternative input devices, such as the mouse, touchscreen, pen devices, character recognition and voice recognition, the keyboard remains the most commonly used and most versatile device used for direct (human) input into computers.
A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or computer commands.
In normal usage, the keyboard is used to type text and numbers into a word processor, text editor or other program. In a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software. Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is also used to give commands to the operating system of a computer, such as Windows’ Control-Alt-Delete combination, which brings up a task window or shuts down the machine. It is the only way to enter commands on a command-line interface.
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MONITOR – A monitor or display (sometimes called a visual display unit) is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray tube about as deep as the screen size.
The first computer monitors used Cathode ray tubes (CRTs), which was the dominant technology until they were replaced by LCD monitors in the 21st Century.
Originally computer monitors were used for data processing while television receivers were used for entertainment. From the 80s onwards, computers have been used for both data processing and entertainment, while televisions have implemented some computer functionality. The common aspect ratio of televisions, and then computer monitors, has also changed from 4:3 to 16:9.
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MOTHERBOARD – In personal computers, a motherboard is the central printed circuit board (PCB) in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple computers, the logic board. It is also sometimes casually shortened to mobo.
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Wikipedia: Computer Motherboard
MOUSE (OPTICAL) – An optical mouse uses a light-emitting diode and photodiodes to detect movement relative to the underlying surface, unlike wheeled mice which use a set of one rolling ball and two chopper wheels for motion detection.
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NETWORK CARD – A network interface controller (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network.
Whereas network interface controllers were commonly implemented on expansion cards that plug into a computer bus, the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard.
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POWER SUPPLY – A power supply unit (PSU) supplies DC power to the other components in a computer. It converts general-purpose alternating current (AC) electric power from the mains (110V to 120V at 60Hz [115V nominal] in North America, parts of South America, Japan, and Taiwan; 220V to 240V at 50Hz [230V nominal] in most of the rest of the world) to low-voltage (for a desktop computer: 12V, 5V, 5VSB, 3V3, -5V, and -12V) direct current (DC) power for the internal components of the computer. Some power supplies have a switch to select either 230 V or 115 V. Other models are able to accept any voltage and frequency between those limits and some models only operate from one of the two mains supply standards.
Most modern desktop computer power supplies conform to the ATX form factor. ATX power supplies are turned on and off by a signal from the motherboard. They also provide a signal to the motherboard to indicate when the DC power lines are correct so that the computer is able to boot-up. While an ATX power supply is connected to the mains supply it provides a 5V stand-by (5VSB) line so that the standby functions on the computer and certain peripherals are powered.
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Wikipedia: ATX
Wikipedia: Power Supply
RAID – Acronym for Redundant Array of Independent Disks (originally Redundant Array of Inexpensive Disks), is a technology that provides increased storage functions and reliability through redundancy. This is achieved by combining multiple disk drive components into a logical unit, where data is distributed across the drives in one of several ways called “RAID levels”; this concept is an example of storage virtualization and was first defined by David A. Patterson, Garth A. Gibson, and Randy Katz at the University of California, Berkeley in 1987 as Redundant Arrays of Inexpensive Disks. Marketers representing industry RAID manufacturers later attempted to reinvent the term to describe a redundant array of independent disks as a means of dissociating a low-cost expectation from RAID technology.
RAID is now used as an umbrella term for computer data storage schemes that can divide and replicate data among multiple physical disk drives. The physical disks are said to be in a RAID array, which is accessed by the operating system as one single disk. The different schemes or architectures are named by the word RAID followed by a number (e.g., RAID 0, RAID 1). Each scheme provides a different balance between two key goals: increase data reliability and increase input/output performance.
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RAM – Random-access memory (RAM) is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in bursts, although the name DRAM / RAM has stuck. However, many types of SRAM, ROM, OTP, and NOR flash are still random access even in a strict sense. RAM is often associated with volatile types of memory (such as DRAM memory modules), where its stored information is lost if the power is removed. Many other types of non-volatile memory are RAM as well, including most types of ROM and a type of flash memory called NOR-Flash. The first RAM modules to come into the market were created in 1951 and were sold until the late 1960s and early 1970s. However, other memory devices (magnetic tapes, disks) can access the storage data in a predetermined order, because mechanical designs only allow this.
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SOLID-STATE DRIVE (SSD) – A solid-state drive (SSD) is a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a traditional block i/o hard disk drive. SSDs are distinguished from traditional hard disk drives (HDDs), which are electromechanical devices containing spinning disks and movable read/write heads. SSDs, in contrast, use microchips which retain data in non-volatile memory chips and contain no moving parts. Compared to electromechanical HDDs, SSDs are typically less susceptible to physical shock, are silent, and have lower access time and latency, but are more expensive per gigabyte (GB) and typically support a limited number of writes over the life of the device. SSDs use the same interface as hard disk drives, thus easily replacing them in most applications.
As of 2010, most SSDs use NAND-based flash memory, which retains memory even without power. SSDs using volatile random-access memory (RAM) also exist for situations which require even faster access, but do not necessarily need data persistence after power loss, or use external power or batteries to maintain the data after power is removed.
A hybrid drive combines the features of an HDD and an SSD in one unit, containing a large HDD, with a smaller SSD cache to improve performance of frequently accessed files. These can offer near-SSD performance in most applications (such as system startup and loading applications) at a lower price than an SSD. These are not suitable for data-intensive work, nor do they offer the other advantages of SSDs.
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Wikipedia: Solid State Drive
Wikipedia: M.2
SOUND CARD – A sound card (also known as an audio card) is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware inside the PC. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education and entertainment (games) and video projection. Many computers have sound capabilities built in, while others require additional expansion cards to provide for audio capability.
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SPEAKERS – Computer speakers, or multimedia speakers, are speakers external to a computer, that disable the lower fidelity built-in speaker. They often have a low-power internal amplifier. The standard audio connection is a 3.5 mm (approximately 1/8 inch) stereo jack plug often color-coded lime green (following the PC 99 standard) for computer sound cards. A plug and socket for a two-wire (signal and ground) coaxial cable that is widely used to connect analog audio and video components. Rows of RCA sockets are found on the backs of stereo amplifier and numerous A/V products. The prong is 1/8″ thick by 5/16″ long. A few use an RCA connector for input. There are also USB speakers which are powered from the 5 volts at 500 milliamps provided by the USB port, allowing about 2.5 watts of output power.
Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer speakers have equalization features such as bass and treble controls.
The internal amplifiers require an external power source, usually an AC adapter. More sophisticated computer speakers can have a subwoofer unit, to enhance bass output, and these units usually include the power amplifiers both for the bass speaker, and the small satellite speakers.
Some computer displays have rather basic speakers built-in. Laptops come with integrated speakers. Restricted space available in laptops means these speakers usually produce low-quality sound.
For some users, a lead connecting computer sound output to an existing stereo system is practical. This normally yields much better results than small low-cost computer speakers. Computer speakers can also serve as an economy amplifier for MP3 player use for those who wish to not use headphones, although some models of computer speakers have headphone jacks of their own.
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TRACKBALL – A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor. Large tracker balls are common on CAD workstations for easy precision. Before the advent of the touchpad, small trackballs were common on portable computers, where there may be no desk space on which to run a mouse. Some small thumbballs clip onto the side of the keyboard and have integral buttons with the same function as mouse buttons. The trackball was invented by Tom Cranston and Fred Longstaff as part of the Royal Canadian Navy’s DATAR system in 1952, eleven years before the mouse was invented. This first trackball used a Canadian five-pin bowling ball.
When mice still used a mechanical design (with slotted ‘chopper’ wheels interrupting a beam of light to measure rotation), trackballs had the advantage of being in contact with the user’s hand, which is generally cleaner than the desk or mousepad and does not drag lint into the chopper wheels. The late 1990s replacement of mouseballs by direct optical tracking put trackballs at a disadvantage and forced them to retreat into niches where their distinctive merits remained more important. Most trackballs now have direct optical tracking which follows dots on the ball.
As with modern mice, most trackballs now have an auxiliary device primarily intended for scrolling. Some have a scroll wheel like most mice, but the most common type is a “scroll ring” which is spun around the ball. Kensington’s SlimBlade Trackball similarly tracks the ball itself in three dimensions for scrolling.
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VIDEO CARD – A video card, video adapter, graphics accelerator card, display adapter, or graphics card is an expansion card which generates output images to a display. Most video cards offer added functions, such as accelerated rendering of 3D scenes and 2D graphics, video capture, TV-tuner adapter, MPEG-2/MPEG-4 decoding, FireWire, light pen, TV output, or the ability to connect multiple monitors (multi-monitor). Other modern high performance video cards are used for more graphically demanding purposes, such as PC games.
Video hardware is often integrated into the motherboard, however all modern motherboards provide expansion ports to which a video card can be attached. In this configuration it is sometimes referred to as a video controller or graphics controller. Modern low-end to mid-range motherboards often include a graphics chipset developed by the developer of the northbridge (i.e. an nForce chipset with Nvidia graphics or an Intel chipset with Intel graphics) on the motherboard. This graphics chip usually has a small quantity of embedded memory and takes some of the system’s main RAM, reducing the total RAM available. This is usually called integrated graphics or on-board graphics, and is low-performance and undesirable for those wishing to run 3D applications. A dedicated graphics card on the other hand has its own RAM and Processor specifically for processing video images, and thus offloads this work from the CPU and system RAM. Almost all of these motherboards allow the disabling of the integrated graphics chip in BIOS, and have an AGP, PCI, or PCI Express slot for adding a higher-performance graphics card in place of the integrated graphics.
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Wikipedia: Video Card
Wikipedia: Video Card – Graphics Processing Unit (GPU)
WEBCAM – A webcam is a video camera which feeds its images in real time to a computer or computer network, often via USB, ethernet or Wi-Fi.
Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera for the World Wide Web gave the webcam its name. Other popular uses include security surveillance and computer vision.
Webcams are known for their low manufacturing cost and flexibility, making them the lowest cost form of videotelephony. They have also become a source of security and privacy issues, as some built-in webcams can be remotely activated via spyware.
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