Transcript 3 - Dhahran British Grammar School

How can you give a computer and instructions?
1. We can type them using a keyboard.
2. We can use the mouse.
3. We can speak an instruction into a
microphone (i.e. use voice recognition)
An Input Device is….

This is used to get data into a system.
 The ideal input devices would be
able to get data into a system as
accurately as possible, in the least
amount of time and preferably
without human intervention.

The keyboard is the oldest and most familiar of all input
devices.

Keyboards are intelligent devices and contain their own chips.

Basically each key acts as a switch which closes when the key is
pressed.
How computer received instructions:
• The microprocessor scans the keyboard hundreds of times a
second to see if a key has been pressed; if it has, a code that
depends on which key has been pressed is sent to the processing
unit.
• The CPU translates this code into an ASCII code (the code that
computers use to represent characters on the computer keyboard),
which is then used by the computer program.

A standard keyboard is called a QWERTY keyboard because
of the arrangement of the letters of the top row of the
alphabet keys.
A concept keyboard consists of a flat – bed of contact switches
covered by a flexible membrane. Programmers can allocate one or
more switches to respond in different ways. Overlays with pictures
and symbols are placed over the membrane.
A concept keyboard consists of a flat – bed of contact switches
covered by a flexible membrane. Programmers can allocate one or
more switches to respond in different ways. Overlays with pictures
and symbols are placed over the membrane.
Who uses concept Keyboard
• In the primary schools - where the overlays are designed with
interesting picture layouts. Children press particular symbols or
pictures in response to the activity being done.
•In the restaurant - where the checkout tills use symbols to speed
up the data entry.
•Hostile environment - for example, on North Sea oil platforms
where the keyboard allows workers to use computer – controlled
machinery through the keyboard without it being damaged by salt
spray or chemicals on the platform.
Who uses concept Keyboard
• Keyboards for disabled – a Braille Keyboard make it easy for
blind users to input data into a computer.
Who uses concept Keyboard
• Visually – impaired users – who have some vision, there are also
keyboards with large coloured keys that are easier to see. Each key
is about one inch square.
A mouse is an input device that translates its movements on the
desktop into digital information; this is fed to the computer which
turns causes the cursor to move on the screen.
A tracker ball is like an upside down mouse. The ball is rotated by
the user in this case the ‘mouse’ stays still.
Advantage compared to a mouse
• the advantage of a tracker ball compared with a conventional
mouse, is that it takes up much less space, and this is why tracker
balls are often seen on laptop computers.
Touch sensitive pads or track pads are commonly found on
notebook computers.
A track pad is a small flat, square pad below the spacebar. As you
move your finger across the track pad’s surface, the pointer moves
across the screen.
A joystick is similar to a tracker ball. Whenever the stick is moved,
the cursor moves in a similar direction on the screen.
Joysticks are mainly used for games but you can also see them being
used with, for example, scanners in hospitals
A screen cursor can be moved by touching the screen with a light
pen.
Light pens are mainly used for design work and need special
software to make them work.
A touch screen is a special kind of screen which is sensitive to
touch. A selection is made from a menu on the screen by touching
part of it.
Commonly use in:
• These screen are ideal for use in banks and building socities,
where customers whore not used to keyboards can obtain
information about the services offered.
•You can also see touch screen in restaurants and bars.
Graphics tablets are rather like electronic tracing paper and, like
paper, they come in all size from a modest A4 to a very large A0
size which will occupy the best part of a desk.
A cursor or puck is used on a graphics tablet to trace over technical
drawings put on the screen using a computer aided design package
such as AutoCAD.
Magnetic stripe are thin strips of magnetic tape, often found on the
back of plastic credit and debit cards. When the card is used, the
stripe passes record and playback heads, similar to a tape recorder,
which reads data form from, and writes data to, the stripe.
Commonly use:
• To withdraw cash from cash dispenser machine (called automatic
teller machines or ATMs) in the walls of banks, building societies
and shopping centres.
In a addition to being able to read the magnetic stripe, some
devices can also write information onto it. The stripe can carry
permanent value, such as an account number or a value that could
change, such as the amount of cash you are allowed to get from an
ATM or cashpoint.
Bar code are made up of black and white stripes of different
thicknesses. These lines represent numbers and are read with a
wand or laser scanner. They are now used on almost all goods sold
in shops and supermarkets, and provide a fast and reliable method
of entering data even when the surfaces being read are curved or
upside down.
Bar code hold information about:
• Product, including the country of manufacture, the name of
the manufacturer, a product item code, and a check digit. They
do no hold information directly for the name, description or price
of the product. When the numbers on the bar code are scanned,
the data is passed to the computer which returns information about
the product.
Barcode reader are commonly use in:
• Supermarkets
•Library systems
•Luggage handling systems at airports and for warehouse stock
control
It is a method of inputting text using a scanner along with a special
software to turn the scanned image into standard ASCII code. In
other words, the text is no longer treated as a picture, since each
individual letter is recognised on its own and can therefore be
edited using word processing software.
How it can be used
• One application of optical character recognition is reading
postcodes on letters at sorting offices so that letters can be sorted
automatically
•OCR software can also be used to scan financial documents such
as company accounts directly into spreadsheet, as well as to scan
text directly into word processors.
Magnetic ink characters are the rather strange looking numbers that
you see at the bottom of cheques. The characters are printed using
an ink which contains iron and may be magnetised. The magnetic
pattern of the numbers is read by a special reader called a
magnetic ink character reader.
The difference between OCR and MICR
• One difference is that one technology uses reflected light, while
the other uses magnetic field patterns produced by the characters.
Another important difference is that OCR systems can recognize
handwriting and different types of text, but MICR needs specially
shaped characters
Optical mark readers are able to sense marks made on a special
form in certain places.
Commonly use for:
• Multiple choice answer sheet marking
•Capturing data from questionnaires and enrolment forms, and the
checking of football pools coupons.
Advantages:
1.
The use of OMR means that details do not have to be typed in;
typing could introduce errors and takes time.
2. OMR reduces the cost of inputting large volumes of data
because people do not need to type the details.
3. The method is useful when results of tests are needed very
quickly, e.g. with an aptitude test for a job.
Disadvantages:
1.
If the forms are being filled in by the general public they very clear
instructions are needed. A couple of examples should be chosen as
an illustration. No matter how clear your instructions are you will find
that a high proportion of forms are filled in incorrectly. The rejection
rate is found to be around 30%.
2. If the forms are creased or folded then they may be rejected or foul
the machine. This will add to time needed to read the forms. Badly
damaged forms will need to be rewritten or keyed in manually.
Punch cards contain holes in different positions which mean
something when they are read by a reader. Before screens and
keyboards were widely used.
Punch cards were the main method of entering data into
computers.
Kimball tag are the small cards with holes punched in them that
you see attached to clothing in certain shops.
How it is use:
1.
When you buy the goods, one of the tags is removed and sent
for processing to a computer centre.
2. A card reader there reads the information contained in the holes
suck as stock number, size, colour and etc. This information is
used to keep stocks records and to re – order stock.
With the voice recognition you speak directly to the computer. It is
particularly useful for handicapped people with limited movement.
It is now popular for inputting data into word processing or
database packages. A micro – phone is the input device for such
systems.
A microphone is used as the input device for a speech
recognition system. The voice pattern of the user is then
converted into instructions to the operating system or applications
software into text on the screen.
A microphone may also be used as an input device to a voice mail
system. Voice mail uses the internet to send, store and receive
voice messages. The system works in a similar way to the e- mail
system but instead of a text message being store on disk, the user’s
voice is stored instead.
The company providing the connection to the internet, called
Internet service provide (ISP) stores the voice message on its
server and when the user logs on the system informs them that
they have a voice mail message.
How it works
Voice use internet to send,
store and receive messages
When the user logs on the system, the ISP server
will informs them that they have a voice mail
message.
The ISP (internet service
provider the provides the
internet connection will
store the message to its
server
EPOS terminals are the cash registers which also act as terminals to
a main computer system. As well as providing customers with
itemised bills, these systems also give useful management
information.
EFTPOS can be able to transfer funds from your bank account
directly to a store’s account using a card called a debit card.
A card that can be use:
A switch card is an example of a debit card in EFTPOS.
Advantage using debit card:
To the person it is a faster method of payment.
To the store the money can be transferred into its accounts instantly
comparing to cheques.
Disadvantage using debit cards:
It can be stolen or forged
Encourage people to spend more money
A video digitiser is a combination of a hardware and software that
converts an analogue signal to digital signal in the computer’s
memory.
How it works
•Each frame from a video is converted, using the video digitiser and it
may be played back in any required.
•Taking a video frame and digitiser is often called image grabbing or
frame grabbing
•Grabbed video images take up a lot of main memory and when stored
use a large amount of disk space.
•Video digitising is used to convert a frame from a video sequence into
a picture, which can be printed in isolation in a magazine or document.
Digitising is also used to make television adverts and to produce pop
video.
Scanners are used to scan text or pictures into a computer’s
memory where they can then be manipulated in some way before
being printed. The can be cheap hand held ones, or flatbed A4 size
or large.
Scanners are also used to scan photographs and pictures for use in
desktop publishing.
Main problem:
•Main problem of scanning images is the amount of space they take up
on the disk.
Digital cameras look just like traditional cameras except they have
no film as such. Instead they have a memory which stores the
image and many of them have special memory cards to give extra
storage. The memory they have, the greater the number of pictures
which can be taken before down – loading. Storage varies widely
between cameras from 40 to 100 pictures.
The amount of memory taken up by a picture depends on its
resolution. The resolution is determined by the number of dots
which make the picture; the greater the number of dots, the crisper
the image. Higher resolution photographs take up more memory so
the camera will store fewer of tem.
A web cameras is simply a digital camera that is used to capture still
images and video images. These images can then be transmitted to
a computer where they are stored in a suitable graphics format. If
required, pictures can be used on a website.
Uses of Webcams:
Advertising
Cruise companies place them on ships so that potential customers can
see what is going on inside a ship and where the ships is at particular
time.
Checking on children in nurseries
All parents worry about child abuse. When they put their children in
nurseries they want to be sure that the children are looked after properly.
Some nurseries have web cams so that parents can see their children on a
computer while they are at work.
Uses of Webcams:
Checking on the weather in another pat of the world
There are web cams just about everywhere. It is possible to see what the
weather is like anywhere in the world if you have access to a web cam
there.
Modern telephones work by having a different tone of each
number key pressed. The different tones that the numbers dialled
are recognised and routed to the correct telephone. Once
connected, a touch tone telephone can be used a s a data entry
device.
Example:
In some banking systems the customer
keys in their identification number using
the phone keys. Once connected, the
customer can select certain services, such
as statement requests, using the same
keypad.
Modern telephones work by having a different tone of each
number key pressed. The different tones that the numbers dialled
are recognised and routed to the correct telephone. Once
connected, a touch tone telephone can be used a s a data entry
device.
Example:
In some banking systems the customer
keys in their identification number using
the phone keys. Once connected, the
customer can select certain services, such
as statement requests, using the same
keypad.
Sensors are used to detect physical quantities outside a computer
such as light, temperature and pressure.
They collect data automatically and usually at regular intervals.
This data can either be transmitted immediately to the computer
or it can be stored for a period of time and a batch of readings
sent in one go.
It use a device called ‘Analogue to Digital Converted’ (ADC)
to process input from sensors. This device converts the analogue
signals from the sensors to digital data that the computer can
process.
Pressure Sensor
Thermal leak detector
Finger print and retinal identification are being used in many
places now and even facial recognition systems are starting to be
introduced.
Biometric authentication methods can be used to identify you at
ATMs to withdraw cash, in computer networks to allow you to log
on and many schools are now introducing ‘fingerprint registration’
Answer the following activities in your book.
 Questions on page 22
Which input device on page 22
Note:
Put all your answers in your book.
Put the date today and the title of the activity which
is ACTIVITY 1: INPUT DEVICE