Overview of Presentation:
• Definition of External device
• Classification of External device
• Some Input device
• Some Output device
• Some Storage device

Definition of External Device
• An external device is a device that it provides a means of exchanging
data between the external environment and the computer.
• An external device attaches to the computer by a link to an I/O
module .
• The link is used to exchange control, status and data.
• An external device is also referred as a Peripheral device or simply
Peripheral .

External Device
• The interface to the I/O module is in form of
control , data and status signals.
• Control signals determine the function that
the device will perform, such as send
data(INPUT / READ), accept data(OUTPUT /
WRITE) etc.
• Data are in the form of a set of bits. Status
signals indicate the state of the device, such as
READY/NOT-READY .
• Control logic controls the device’s opertation.
• Transducer converts data from electrical to
other from and vice versa.
• Buffer holds the data temporarily.

Classification of External Device
• There are many different external devices, but they
fall into three general categories:
• Input devices, such as a keyboard and a mouse
• Output devices, such as a monitor and a printer
• Storage devices, such as a hard drive or flash drive

Input Devices
• In computing, an input device is a external device (piece of computer
hardware equipment) used to provide data and control signals to a
computer.
• There are many types of input devices, such as
• Keyboard
• Mouse
• Scanner
• Microphone
• Joystick ,etc

Keyboard
• Most common input device used with
computer.
• Keyboards allow to input letter, numbers and
other symbols into a computer.
• It has some major types of key, such as control
keys, function keys, alphanumeric keys,
numeric keys
• Each character is associated with a 7 or 8 bit
code.
• Keyboard connects to the computer using
either USB or Bluetooth for wireless
communication

Mouse
• A computer mouse is a pointing
device (hand control) that detects
two-dimensional motion.
• Physically, a mouse consists of an
object held in one's hand, with
one or more buttons.
• There are many types of mouse,
such as Wireless, Gstick, Optical,
Trackball, Mechanical etc.

Output Device
• An output device is any device used to send data from a computer to
another device or user. Most computer data output that is meant for
humans is in the form of audio or video.
• There are many types of output devices, such as
• Monitor
• Printer
• Projector
• Speaker etc.

Output Device
• The most common output
device in computer .
• It converts the electrical
signal to character or
other form.
• It allows the user to
interact with the
computer, typically using
the keyboard and mouse.

Printer
• A printer is a peripheral
which makes a human-
readable representation of
graphics or text on paper or
similar physical media.
• It can print documents
stored on memory cards or
from digital cameras and
scanners.

Storage Device
• A storage device is any computing hardware that is used for storing
and extracting data files and objects. It can hold and store
information both temporarily and permanently, and can be internal or
external to a computer.
• Some storage device are
• Hard Drive
• Floppy disk
• Memory card
• USB flash drive etc.

Hard Drive
• Hard disk is also known as HDD
(abbreviation), hard drive, disk drive,
fixed drive, fixed disk, fixed disk drive.
• data storage device that uses magnetic
storage to store and retrieve digital
information
• The operating system, software and
most other files are stored in the hard
disk drive.
• The hard drive is sometimes referred to
as the "C drive" Hard Disk

Floppy disk
• A floppy disk, or diskette, 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 are used for emergency boots in
systems lacking support for other bootable
media, and for BIOS can still be executed from
bootable floppy disks. If BIOS updates fail or
become corrupt, floppy drives can sometimes
be used to perform a recovery.

Memory cards
• A memory card or flash card is an
electronic flash memory data storage
device used for storing digital
information.
• Used in
• Digital Cameras
• Cell phones
• Camcorders
• Portable audio
• DVD and video players

Flash drive
• A USB drive is a data storage device
that includes flash memory with an
integrated Universal Serial Bus (USB)
interface
• USB flash drives use the USB mass
storage standard, supported natively
by modern operating systems such as
Linux, Mac OS X, Windows, and other
Unix-like systems, as well as many
BIOS boot ROMs