Transcript From the Keyboard to the Computer

INPUT
AND
OUTPUT
DEVICES
INPUT DEVICES
 are devices we use to put
information into a computer.
KEYBOARD
Keyboard Basics
A keyboard's primary function is to act as an input device.
Using a keyboard, we can type a document, use keystroke
shortcuts, access menus, play games and perform a variety of
other tasks. Keyboards can have different keys depending on the
manufacturer, the operating system they're designed for, and
whether they are attached to a desktop computer or part of a
laptop. But for the most part, these keys, also called keycaps, are
the same size and shape from keyboard to keyboard. They're also
placed at a similar distance from one another in a similar pattern,
no matter what language or alphabet the keys represent.
Most keyboards have between 80 and 110 keys, including
typing keys, numeric keypad, function keys, and control keys.
In 1986, IBM further extended the basic
keyboard with the addition of function and
control keys. Applications and operating
systems can assign specific commands to the
function keys. Control keys provide cursor and
screen control. Four arrow keys arranged in an
inverted T formation between the typing keys
and numeric keypad move the cursor on the
screen in small increments. Other common
control keys include Home, End, Insert, Delete,
Page Up, Page Down, Control (Ctrl), Alternate
(Alt), Escape (Esc)
The Windows keyboard adds some extra
control keys: two Windows or Start keys, and
an Application key.
The microprocessor and controller
circuitry of a keyboard.
The key matrix
Keyboard Switches
This keyboard uses rubber dome switches.
Non-Traditional Keyboard
Blue backlit
keyboard 'off'
Blue backlit
keyboard 'on'
Illuminated keyboards, like the Ion Illuminated
Keyboard, use light-emitting diodes or
electroluminescent film to send light through the
keys or the spaces between keys.
From the Keyboard
to the Computer
As you type, the processor in the keyboard analyzes
the key matrix and determines what characters to
send to the computer. It maintains these characters in
its memory buffer and then sends the data.
A PS/2 type keyboard connector.
Microsoft wireless keyboard
SCANNER
The basic principle of a scanner is to
analyze an image and process it in some way.
Image and text capture (optical character
recognition or OCR) allow you to save
information to a file on your computer. You can
then alter or enhance the image, print it out or
use it on your Web page.
Flatbed scanners, also called desktop
scanners, are the most versatile and commonly
used scanners.
A typical flatbed scanner has
Charge-coupled device (CCD) array, Mirrors,
Scan head, Glass plate, Lamp, Lens, Cover,
Filters, Stepper motor, Stabilizer bar, Belt, Power
supply. Interface port (s), and Control circuitry.
Sheet-fed scanners are similar to flatbed scanners
except the document is moved and the scan head is
immobile. A sheet-fed scanner looks a lot like a small
portable printer.
Handheld scanners use the same basic technology as
a flatbed scanner, but rely on the user to move them
instead of a motorized belt. This type of scanner
typically does not provide good image quality.
However, it can be useful for quickly capturing text.
Drum scanners are used by the publishing industry to
capture incredibly detailed images.
The core component of the scanner
Close-up of the CCD array
The Scanning Process
the fluorescent lamp on top of the scan head.
The document is placed on the glass plate
and the cover is closed.
The image of the document is reflected by an
angled mirror to another mirror. In some scanners,
there are only two mirrors while others use a three
mirror approach. Each mirror is slightly curved to focus
the image it reflects onto a smaller surface. The last
mirror reflects the image onto a lens. The lens focuses
the image through a filter on the CCD array.
The filter and lens arrangement vary based on
the scanner. Some scanners use a three pass scanning
method. Each pass uses a different color filter (red,
green or blue) between the lens and CCD array. After
the three passes are completed, the scanner software
assembles the three filtered images into a single fullcolor image.
Image Transfer




Parallel - Connecting through the parallel port is the slowest
transfer method available.
Small Computer System Interface (SCSI) - SCSI requires a
special SCSI connection. Most SCSI scanners include a
dedicated SCSI card to insert into your computer and connect
the scanner to, but you can use a standard SCSI controller
instead.
Universal Serial Bus (USB) - USB scanners combine good
speed, ease of use and affordability in a single package.
FireWire - Usually found on higher-end scanners, FireWire
connections are faster than USB and SCSI. FireWire is ideal for
scanning high-resolution images.
OUTPUT
DEVICES
 are devices we use to get
information out of a
computer.
MONITOR

A monitor is the screen on
which words, numbers, and graphics can
be seen. It is the most common output
device.
LCDs
vs. CRTs
Advantages of LCD
Monitors
Require less power
 Smaller and weigh less
 More adjustable
 Less eye strain

Advantages of CRT Monitors
Less expensive
 Better color representation
 More responsive
 Multiple resolutions
 More rugged

Dual Monitors
One way to expand your computer's
display is to add a second monitor. Using
dual monitors can make you more
productive and add a lot to your
computing experience.
With two monitors, you can:
View large spreadsheets
 Make changes to a web page's code on
one monitor and view the results on the
second
 Open two different applications, such as a
Word document on one monitor and your
web browser on the second

Headset
Canalphones
(also known as in-ear monitors, or IEMs)
are earphones that are inserted directly
into the ear canal. Canalphones offer
portability similar to ear buds, and also act
as earplugs to block out environmental
noise.
Webcam
A webcam is a video capture
device connected to a computer or
computer network, often using a
USB port or, if connected to a
network, Ethernet or Wi-Fi.