INFO1 complete notes

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  • Created on: 28-04-11 09:19
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Data types
text
still and moving images
numbers
sound
Input devices
Keyboards
· Most common type of keyboards is the qwerty keyboard
· Another type of keyboard is a concept keyboard. They can be specially designed so
that people with restricted vision can use them to interact with a computer. Most
commonly programmed to perform common commands with one key.
Point and click devices
· Include mouse, tracker balls, touch sensitive pad, joystick, light pens, touch
screens and graphic tablets
· A mouse translates movement on a desktop into digital information. This
information is converted into movement of the cursor on the screen. Am mouse
will also have buttons which can be clicked to help the user select what functions
they want to use.
· A tracker ball is essentially an upside down mouse.
· Instead of moving a mouse on a surface, the ball is rotated. It achieves the same
results as a mouse, just with less space.
· Touch sensitive pads are most commonly found on laptops a stylus or the users
finger are touched gently on the ad and as it is moved the curser on the screen
moves.
· Joysticks are commonly used to interact with computer games, although they
are also used in other circumstances (hospital scanners) like a tracker ball movement
of the joystick is reflected by the movement on the screen
· A Light pen uses specialist software and is used in specialist situations. The light
pen works by being touched on the screen. As the pen is moved on the screen the
curser moves.
· Touch screens are a special type of screen that is sensitive to touch. Selections
can be made by touching the screen. They are most commonly used in banks, shops
and building societies. No training is necessary to use the touch screen.
· A graphics tablet allows the user to create designs directly onto the screen. A
special stylus is connected to the computer via the tablet. As the user `draws' on
the tablet the drawing appears on the screen.
Readers
· Readers are the most common type of automatic input.
· The most common types are magnetic tape readers, barcode readers, optical
character readers, optical card readers, optical mark readers and magnetic ink
readers.

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The most common Magnetic strip readers are those used at electronic point of
sale. The `read' the data stored on the magnetic strip of the card.
· Barcode readers are used in shops and libraries. The bars on the barcode represent
numbers and can be scanned very quickly using a laser scanner.
· Optical character recognition is a method of inputting text using a scanner. It
requires specialist software to convert the scanned image into an ASCII code.…read more

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Printers
· Dot matrix- the oldest, not really used much. The quality is poor. It uses carbon
ribbons and pins. Because it is an impact printer it can be used to make duplicate prints
using carbon paper, which is useful when multiple copies of documents are required.
· Inkjets- this printer has become cheap and commonly used at home. They are perfect
for small quantities of work. The ink jet uses ink cartridges that are heated up then dropped
onto the paper forming characters.…read more

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Storage
Reasons for storing data:
basic setup and operating systems are required for the computer to work
application software needs to be available for the user to carry out tasks
files created by the user need to be stored so that they can be used again
data may need to be transferred from one device to another
backup copies need to be taken in case the original files are lost or have become
corrupt
File compression
TIFF files are created when scanning a photograph, however…read more

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RAM- random access memory, the data is temporary; RAM is known as volatile memory. A
computer with more RAM will operate faster. It is fast access but smaller than the backing
storage.
ROM- read only memory. The data is permanent, it has non-volatile memory. Amount of
ROM in a computer is small compared to RAM. It contains permanent data and programs for
the CPU.
External
The most common form of external storage used to be in a personal computer was a 3.5"
floppy disk.…read more

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Physical size of device
Software
The software of a computer system is the various sets of instructions which tell the
system how to do things.…read more

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Health and safety
Health and safety at work act
The health and safety in any situation is approached by carrying out a risk assessment of the
situation.…read more

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