The document describes several common computer hardware components. It discusses hard disks for secondary storage, central processing units (CPUs) that perform computations, random access memory (RAM) for temporary data storage, graphics cards that generate video output, optical disc drives like CD-ROMs, motherboards that connect major components, and more. The document provides details on the purpose and basic functioning of each part.

1. Computer Hardware
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2. Computer Parts
 Hard Disk  Monitor
 Central Processing Unit  Mouse
 RAM  Key Board
 Graphics Card  Printer
 CD-ROM  Speaker
 Mother Board  UPS
 Floppy Drive  Web Cam
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3. Hard Disk
 A hard disk drive is a device for storing and retrieving
digital information, primarily computer data. It consists
of one or more rigid rapidly rotating discs (often
referred to as platters), coated with magnetic material
and with magnetic heads arranged to write data to the
surfaces and read it from them.
 Hard drives are classified as non-volatile, random
access, digital, magnetic, data storage devices.
Introduced by IBM in 1956, hard disk drives have
decreased in cost and physical size over the years while
dramatically increasing in capacity and speed.
 Hard disk drives have been the dominant device for
secondary storage of data in general purpose
computers since the early 1960s. They have maintained
this position because advances in their recording
capacity, cost, reliability, and speed have kept pace with
the requirements for secondary storage.
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4. Processor
 The central processing unit (CPU) is the portion of a computer
system that carries out the instructions of a computer
program, to perform the basic arithmetical, logical, and
input/output operations of the system. The CPU plays a role
somewhat analogous to the brain in the computer. 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.
 On large machines, CPUs require one or more printed circuit
boards. On personal computers and small workstations, the CPU
is housed in a single silicon chip called a microprocessor. Since
the 1970s the microprocessor class of CPUs has almost
completely overtaken all other CPU implementations. Modern
CPUs are large scale integrated circuits in packages typically less
than four centimeters square, with hundreds of connecting pins.
 Two typical components of a CPU are the arithmetic logic unit
(ALU), which performs arithmetic and logical operations, and the
control unit (CU), which extracts instructions from memory and
decodes and executes them, calling on the ALU when necessary.
 Not all computational systems rely on a central processing unit.
An array processor or vector processor has multiple parallel
computing elements, with no one unit considered the "center".
In the distributed computing model, problems are solved by a
distributed interconnected set of processors.
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5. 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.
 Other memory devices (magnetic tapes, floppy
discs, CDs and DVDs) can access the storage data only
in a predetermined order, because of mechanical
design limitations
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6. Graphics Card
 A video card, display card, graphics card, or graphics
adapter is an expansion card which generates a feed of
output images to a display. Most video cards offer various
functions such as accelerated rendering of 3D scenes and
2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the
ability to connect multiple monitors.
 Video hardware can be integrated into the motherboard
but recently it has been integrated into the CPU, however
all modern motherboards, and even motherboards from
the 90's 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. 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 usually low in
performance and undesirable for those wishing to run 3D
applications, but the new Ivy Bridge CPU's, will contain
graphics capable of running 3D applications. A dedicated
graphics card on the other hand has its own Random
Access Memory or 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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7. CD-ROM
 In computing, an optical disc drive (ODD) is a disk drive that uses
laser light or electromagnetic waves near the light spectrum
as part of the process of reading or writing data to or from
optical discs. Some drives can only read from discs, but
recent drives are commonly both readers and
recorders, also called burners or writers. Compact
discs, DVDs, and Blu-ray discs are common types of optical
media which can be read and recorded by such drives.
Optical drive is the generic name; drives are usually
described as "CD" "DVD", or "Blu-Ray", followed by
"drive", "writer", etc.
 Disc recording is restricted to storing files playable on
consumer appliances (films, music, etc.), relatively small
volumes of data (e.g., a standard DVD holds 4.7 gigabytes)
for local use, and data for distribution, but only on a small-
scale; mass-producing large numbers of identical discs is
cheaper and faster than individual recording.
 Optical discs are used to back up relatively small volumes
of data, but backing up of entire hard drives, as of
2011[update] typically containing many hundreds of
gigabytes, is less practical than with the smaller capacities
available previously. Large backups are often made on
external hard drives, as their price has dropped to a level
making this viable; in professional environments magnetic
tape drives are also used.
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8. Mother Board
 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
main board, system board, or, on Apple computers, the
logic board. It is also sometimes casually shortened to
mobo.
 A motherboard, like a backplane, provides the electrical
connections by which the other components of the system
communicate, but unlike a backplane, it also connects the
central processing unit and hosts other subsystems and
devices.
 A typical desktop computers has its microprocessor, main
memory , and other essential components connected to
the motherboard. Other components such as external
storage, controllers for video display and sound, and
peripheral devices may be attached to the motherboard as
plug-in cards or via cables, although in modern computers
it is increasingly common to integrate some of these
peripherals into the motherboard itself.
 An important component of a motherboard is the
microprocessor's supporting chipset, which provides the
supporting interfaces between the CPU and the various
buses and external components. This chipset
determines, to an extent, the features and capabilities of
the motherboard.
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9. Floppy Drive
 A floppy disk is a disk storage medium composed of a disk
of thin and flexible magnetic storage medium, sealed in a
rectangular plastic carrier lined with fabric that removes
dust particles. They are read and written by a floppy disk
drive (FDD).
 Floppy disks, initially as 8-inch (200 mm) media and later in
5.25-inch (133 mm) and 3.5-inch (89 mm) sizes, were a
ubiquitous form of data storage and exchange from the
mid-1970s well into the first decade of the 21st century.
 By 2010, computer motherboards were rarely
manufactured with floppy drive support; 3 1⁄2" floppies
could be used as an external USB drive, but 5 1⁄4", 8", and
non-standard drives could only be handled by old
equipment.
 While floppy disk drives still have some limited
uses, especially with legacy industrial computer
equipment, they have been superseded by data storage
methods with much greater capacity, such as USB flash
drives, portable external hard disk drives, optical
discs, memory cards, and computer networks.
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10. Monitor
 A monitor or display (also called screen or 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.
 Originally, computer monitors were used for data
processing while television receivers were used
for entertainment. From the 1980s
onwards, computers (and their monitors) 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 and 16:10.
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11. Mouse
 A mouse is a pointing device that
functions by detecting two-dimensional
motion relative to its supporting surface.
Physically, a mouse consists of an object
held under one of the user's hands, with
one or more buttons. It sometimes
features other elements, such as
"wheels", which allow the user to
perform various system-dependent
operations, or extra buttons or features
that can add more control or dimensional
input. The mouse's motion typically
translates into the motion of a pointer on
a display, which allows for fine control of
a graphical user interface.
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12. Key Board
 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 teleprompter-style
keyboards became the main input device for
computers.
 Despite the development of alternative input
devices, such as the mouse, touch screen, 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.
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13. Printer
 In computing, a printer is a peripheral which produces a text or
graphics of documents stored in electronic form, usually on
physical print media such as paper or transparencies. Many
printers are primarily used as local peripherals, and are attached
by a printer cable or, in most new printers, a USB cable to a
computer which serves as a document source.
 Some printers, commonly known as network printers, have built-
in network interfaces, typically wireless or Ethernet based, and
can serve as a hard copy device for any user on the network.
Individual printers are often designed to support both local and
network connected users at the same time. In addition, a few
modern printers can directly interface to electronic media such
as memory cards, or to image capture devices such as digital
cameras and scanners; some printers are combined with
scanners or fax machines in a single unit, and can function as
photocopiers. Printers that include non-printing features are
sometimes called multifunction printers (MFP), multi-function
devices (MFD), or all-in-one (AIO) printers. Most MFPs include
printing, scanning, and copying among their many features.
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14. Speaker
 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 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.
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15. UPS
 An uninterruptible power supply, also uninterruptible
power source, UPS or battery/flywheel backup, is an
electrical apparatus that provides emergency power to a
load when the input power source, typically mains
power, fails. A UPS differs from an auxiliary or emergency
power system or standby generator in that it will provide
instantaneous or near-instantaneous protection from
input power interruptions by means of one or more
attached batteries and associated electronic circuitry for
low power users, and or by means of diesel generators and
flywheels for high power users. The on-battery runtime of
most uninterruptible power sources is relatively short—5–
15 minutes being typical for smaller units—but sufficient
to allow time to bring an auxiliary power source on line, or
to properly shut down the protected equipment.
 While not limited to protecting any particular type of
equipment, a UPS is typically used to protect
computers, data centers, telecommunication equipment
or other electrical equipment where an unexpected power
disruption could cause injuries, fatalities, serious business
disruption or data loss. UPS units range in size from units
designed to protect a single computer without a video
monitor (around 200 VA rating) to large units powering
entire data centers, buildings, or even cities.
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16. Web Cam
 A webcam is a video camera that 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. The common
use as a video camera for the World Wide
Web gave the webcam its name. Other
popular uses include security
surveillance, computer vision, video
broadcasting and for recording social
videos .
 Webcams are known for their low
manufacturing cost and flexibility, making
them the lowest cost form of video
telephony. 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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