F-COMP 002 Computers

F-COMP 002 Computers
F-COMP 002
Papakonstantinou Koula
40 %
• Final exam
60 %
Computer Lab rules
 Eat and drink OUTSIDE the lab
 Be careful handling computers
 Make sure you listen the directions
 Open only your work
 Never delete, rename or remove anything from the computer
unless directed by teacher
 Do not change any computer settings
 Remain seated and work quietly
Types and components of
What is a computer?
 A computer is an electronic device that manipulates
information, or data.
 It has the ability to store, retrieve, and process data.
 Computer is used to type documents, send email, play
games, and browse the Web.
 Computer is used it to edit or
create spreadsheets, presentations, and even videos.
What is Hardware?
 Hardware is the physical parts of the computer system –
the parts that you can touch and see.
What is software?
 Software is a collection of instructions that can be ‘run’
on a computer. These instructions tell the computer what to
 Software is not a physical thing it is just a bunch of codes.
Software Types
 Systems software
Programs that allow the hardware to run properly e.g
operating systems
 Applications software
Programs that allow the user to do specific tasks e.g browser,
Operating System
Tasks of an operating system
 Controlling the operation of the input, output and
backing storage devices
Supervising the loading, running and storage of
applications programs
Dealing with errors that occur in applications
Maintaining security of the whole computer system
Maintaining a computer log
Allowing communication between user and the
operating system – user interface
Command line interfaces
 Require a user to type in instructions in order to choose
options from menu
 Number of command to type in
 User has to learn a lot of commands just to carry out basic
Graphical user interface
 User interacts with computer using pictures or symbols
 Menus
 Right click, left click
 Icons
 Buttons
Types of Computers
 Fastest
 Most expensive
 Used for scientific and engineering applications
 Weather forecasting
Mainframe computers
 Very powerful
 Can have hundreds of simultaneous users
 Used by large companies for data processing
 Networks servers on internet
Personal Digital Assistants (PDAs)
 Small hand-held computers
 Use a touch screen
 Storing contacts information, keeping dairy, making notes,
sending and receiving emails
 Palmtop devices
 Most common
 Desktop – Notebook
Notebook computers
 Light and easy to carry around.
 No trailing wires
 Easy to steal
 Limited battery life
Embedded computers
 Washing machines
 Telephones
 Cameras
 Input from a device’s sensors and output control the
operation of the device
 Central heating system
Computer System
 Inputs
Raw data fed into an information system
 Processing
The way information systems convert raw data
into useful information
 Storage
Data is stored in an information system, so that
it can be utilised when required.
 Outputs
The visible or audible result of data processing.
Information that can be used.
Input devices
Alphanumeric Keyboard
 A very common, general purpose, input device that
allows text(abc…), numbers (123…)
and symbols (%[email protected]) to be entered into a computer.
 A keyboard is simply a set of buttons. Each button has a
symbol assigned.
Numeric Keypad
 A small keyboard that only has numbers.
 Used to enter numeric data into computers such as those
in ATMs.
 Most computer keyboards have a numeric keypad on the
right side, and most mobile phones (there are also
computers) have a one for entering phone numbers, etc.
 This is a device with a numeric keypad used to enter a
person’s Personal Identity Number (PIN) e.g. when
paying with a credit card.
 PIN pads are also found on electronic door locks – you
enter a PIN to unlock the door.
 A pointing device found on most PCs. Sensors on the
bottom of the mouse detect when the mouse is moved. Data
about this movement is sent to the computer.
 Often used to control the pointer in a GUI.
 A pointing device found on most laptops. Used instead of
a mouse since it takes up less space. The user moves a finger
across the touch pad and this movement data is sent to the
 Usually used to control the pointer in a GUI.
Trackball / Tracker Ball
 This pointing device is not moved about like a mouse,
instead it has a large ball that the user spins. Data about
which direction the ball is spun is passed to the computer.
 It can be used to control a GUI pointer.
 Tracker balls are often used by people with limited
movement(disabled) or by the very young since they
are easier to use than a mouse.
Graphics Tablet
 A pointing device often used by designers and artists to
allow natural hand movements to be input
to graphics applications.
 A stylus is held like a pen and moved over the surface of the
tablet. Data about the stylus movements are sent to the
Joystick / Joypad
 Used mainly for playing games. The user moves the joystick
left/right, forward/back and data about these movements
are sent to the computer.
 Small joysticks can also be found on some mobile phones.
 A device that ‘scans’ images, book pages, etc.
 Scanning is basically taking a close-up photograph (just very
slowly and with great detail). The scanned image data is
passed to the computer.
 Scanned images can be further processed once inside the
computer, e.g. OCR of printed text.
Digital Camera
 A device that captures digital photographs.
 Most digital cameras do not directly input data into a
computer - they store photographs on memory cards. The
photographs can later be transferred to a computer.
 A modern digital camera can capture 10 Megapixels or more
per photograph - that’s 10,000,000 colored dots (pixels) in
every photo!
Web Cam
 This is a very basic video camera used to feed live
video into a computer.
 The video data from a web cam is low quality compared to
a full video camera. However it is good enough for web
 Usually a web cam is clipped to the top of a monitor, but
many laptops now have web cams built into the edge of the
 An input device that converts sound into a signal that can be
fed into a computer.
 The signal from a microphone is usually analogue so, before
it can be processed by a computer, it must be converted into
digital data. An Analogue-to-Digital Convertor
(ADC) is used for this (usually built into the computer’s
sound card)
Magnetic Strip Reader
 Many plastic cards, such as credit cards, have a strip of
material that can be magnetised on the back. Data can
be stored here in the form of magnetised dots.
 Usually the data stored on this strip in the same data
shown on the front of the card (e.g. the credit card
number, expiry date and customer name).
 The stripe allows this data to be input to a computer
system faster and more accurately than by typing it in.
 A magnetic strip/stripe reader is used to read the data from
the stripe. This is usually done by ‘swiping’ the card through
a slot on the reader.
Smart Card / 'Chip' Reader
 Modern credit cards and ID cards don’t use a magnetic strip.
Instead they have a tiny ‘chip’ of computer memory embedded
inside them. (These cards are often referred to as smart cards.)
 Data can be stored in this memory and read back using a ‘chip’
 A card is inserted into the reader where metal contacts connect to
the metal pads on the front face of the card. The reader can
then access the memory chip and the data stored on it.
 Smart cards can store much more data than magnetic strip
cards, e.g. an ID smart card would store not only the owner’s
name and card number, but might also have a digital image of the
MICR Reader
 Magnetic Ink Character Recognition (MICR) is a
technology that allows details from bank cheques to be
read into a computer quickly and accurately.
 The cheque number and bank account number are
printed at the bottom of each bank cheque in special
magnetic ink using a special font. These numbers
can be detected by an MICR reader.
OMR Scanner
 Optical Mark Recognition (OMR) is a technology that
allows the data from a multiple-choice type form to be
read quickly and accurately into a computer.
 Special OMR forms are used which have spaces that can
be colored in (usually using a pencil). These marks can
then be detected by an OMR scanner.
 Common uses of OMR are multiple-choice exam answer
sheets and lottery number forms.
OCR Scanner
 Optical Character Recognition (OCR) is a software
technology that can convert images of text into an
actual text file that can then be edited (e.g. using wordprocessing software). The result is just as if the text had been
typed in by hand.
 OCR is typically used after a page of a book has
been scanned. The scanned image of the page is
then analysed by the OCR software which looks for
recognisable letter shapes and generates a matching text
Barcode Reader / Scanner
 A barcode is simply a numeric code represented as a series
of lines.
 These lines can be read by a barcode reader/scanner.
 The most common use of barcode readers is at Point-ofSale (POS) in a shop. The code for each item to be
purchased needs to be entered into the computer.
 Reading the barcode is far quicker and
more accurate than typing in each code using a keypad.
Output devices
Flat-Screen Monitor (TFT or LCD)
 Flat-screen monitors are light in weight and they take up
very little desk space.
Digital / Multimedia Projector
 Digital projectors are used in situations when a very large
viewing area is required, for example
during presentations, for advertising, or in your home
for watching movies.
 A projector connects to a computer, a DVD player or a
satellite receiver just like a ordinary monitor.
 The image is produced inside the device and then projected
out through a large lens, using a powerful light source.
 If you want to hear music or sounds from your computer,
you will have to attach loudspeakers. They convert electrical
signals into sound waves.
 Loudspeakers are essential for applications such as music
editing, video conferencing, watching movies, etc.
Dot Matrix Printer
 A dot-matrix printer is named after the pattern (a grid or
‘matrix’) of dots used when creating the paper printout.
Dot-matrix print quality is poor
The printers are noisy
Dot matrix printers often use continuous stationary:
long, continuous strips of paper
Several ‘carbon-copies’ can be printed in one go.
InkJet Printer
 Cheap, high-quality, full-color printing
 These printers have a similar print-head mechanism to a dot
matrix printer.
Several colored inks can be used to produce full-color printouts.
Ink-jet printers are very quiet in use
They are also cheap to manufacture and thus cheap to purchase
The ink is very expensive to buy so the printers are expensive
to use.
Laser Printer
 Laser printers are very complex devices, and
thus expensive to buy.
 They are very cheap to use.
 The laser and toner system allows very fast
printing compared to other printers
 Laser printers are very common in offices since they print
very quickly, are cheap to use and are reasonably quiet.
 Plotters are often used by designers and architects since
they work with huge pieces of paper, far bigger than
anything a normal printer could work with
Input output devices
Touch Screen
 A touch screen is an alternative to a separate pointing device.
 With a touch screen the user selects items on the screen
by touching the surface.
 This makes touch screen systems very intuitive and simple
to use.
 Often used for information terminals in public places e.g.
libraries or museums where mice or keyboards may be stolen
or damaged.
Headphones with microphones
 Headphones with microphones are with chat and phone
Computer activity
Exercise 1
The block diagram represents the parts of a computer system.
Which parts represent :
 A printer …….
 A mouse or keyboard ……
 A disk drive …..
Exercise 2
Fashion Store is a high street shop selling clothing
Give the name of TWO input devices that must be part of the
shop’s work station
 Input device one …………
 Input device two ………..
Give the name of TWO output devices that must be part of the
shop’s system.
 Output device one ……..
 Output device two …….
Exercise 3
Tick true or false next to each of these statements.
Input devices are examples of hardware
A mainframe computer can’t be carried around
Chip reader is a part of operating system
Barcode reader is an output device
Answers to multiple choice examination questions are
recorded using an OCR sheet
Spreadsheet software would be used to create a
burglar alarm system
MICR is used for reading data from the bar code on a
food item
Dot matrix printers are very noisy
Laser printers are easy to use if continuous stationery
is required
Touch screen are examples of input-output device
Exercise 4
Storage Devices and Media
What is Data Storage?
 Putting the data in a known place.
 We can later come back to that place and get our data back
 ‘Writing’ data or ‘saving’ data are other ways of saying
‘storing’ data.
 ‘Reading’ data, ‘retrieving’ data or ‘opening’ a file are
ways of saying that we are getting our data back from its
storage location.
Main Memory
 Main memory (sometimes known as internal
memory or primary storage) is another name
for RAM and ROM.
 Main memory is usually used to store data temporarily.
 It is volatile (this means that when power is switched off all
of the data in the memory disappears).
 Main memory is used to store data whilst it is
being processed by the CPU. Data can be put into
memory, and read back from it, very quickly
Backing Storage
 Backing storage is the name for all other data storage
devices in a computer: hard-drive, etc.
 Backing storage is usually non-volatile, so it is generally
used to store data for a long time.
Storage Media & Devices
 The device that actually holds the data is known as
the storage medium (‘media’ is the plural).
 The device that saves data onto the storage medium, or reads
data from it, is known as the storage device.
 Sometimes the storage medium is a fixed (permanent) part
of the storage device, e.g. the magnetic coated discs built into
a hard drive
 Sometimes the storage medium is removable from the
device, e.g. a CD-ROM can be taken out of a CD drive.
Accessing Stored Data
 Serial / Sequential Access
 Direct / Random Access
Serial / Sequential Access
 A serial (or sequential) access storage device is one that
stores files one-by-one in a sequence.
 Systems that store things on tape (video, music, computer data, etc.)
are always serial access
Direct / Random Access
 A direct (or ‘random’) access storage device is one that stores
files so that they can be instantly accessed - there is no
need to search through other files to get to the one you want.
Data Storage Capacity
Data Storage Capacity
 Data storage capacity is measured in bytes (B).
 A thousand bytes is known as a kilobyte (kB)
1,000B = 1kB
 A million bytes is known as amegabyte (MB)
1,000,000B = 1MB
 A thousand million bytes is called a gigabyte (GB)
1,000,000,000B = 1GB
 A million million bytes is called a terabyte (TB)
1,000,000,000,000B = 1TB
Magnetic Storage Devices
Why Magnetic?
 Magnetic storage media and devices store data in the form of
tiny magnetised dots.
 These dots are created, read and erased using magnetic fields
created by very tiny electromagnets.
Hard Drives
 Hard-drives have a very large storage capacity (up to
 They can be used to store vast amounts of data.
 Hard-drives are random access devices and can be used to
store all types of films, including huge files such as movies.
 Data access speeds are very fast.
Portable Hard Drive
 A portable hard-drive is one that is placed into a small
case along with some electronics that allow the hard-drive to
be accessed using a USB or similar connection.
 Portable hard-drives allow very large amounts of data to
be transported from computer to computer.
Magnetic Tape
 Magnetic tape is a large capacity, serial access medium.
Because it is a serial access medium, accessing individual files
on a tape is slow.
 Tapes are used where large amounts of data need to be
stored, but where quick access to individual files is not
 A typical use is for data back-up (lots of data, but rarely
only accessed in an emergency)
Floppy Disc
 A removable, portable, cheap, low-capacity (1.44MB)
storage medium.
 Floppy discs are random access devices used for transfer
small amounts of data between computers, or to back-up
small files, etc.
 Access times are slow.
Zip Disc
 A removable and portable storage medium, similar in
appearance to a floppy disk, but with a much higher
capacity (100MB, 250MB or 750MB).
 Zip discs are random access devices which were used for
data back-up or moving large files between computers.
Jaz Disc
 A removable and portable storage medium based on
hard-drive technology, with a large capacity (1GB or
 Jaz discs are random access devices which were used for
data back-up or moving large files between computers.
 Discs were expensive to buy and not very reliable.
Optical Storage Devices
Why 'Optical'?
 Optical storage devices save data as patterns of dots that can
be read using light. A laser beam is the usual light source.
 The data on the storage medium is read by bouncing the laser
beam off the surface of the medium. If the beam hits a dot it
is reflected back differently to how it would be if there
were no dot. This difference can be detected, so the data can
be read.
 Compact Disc - Read-Only Memory (CD-ROM) discs can
hold around800MB of data.
 The data cannot be altered (non-volatile), so cannot be
accidently deleted. CD-ROMs are random-access devices.
 CD-ROMs are used to distribute all sorts of
data: software (e.g. office applications or games), music,
electronic books (e.g. an encyclopaedia with sound and
 Digital Versatile Disc - Read-Only Memory (DVD-ROM)
discs can hold around 4.7GB of data (a dual-layer DVD can
hold twice that). DVD-ROMs are random-access devices.
 DVD-ROMs are used in the same way as CD-ROMs (see
above) but, since they can hold more data, they are also used
to store high-quality video.
 Blu-Ray disks are a recent replacement for DVDs. A Blu-Ray
disc can hold 25 - 50GB of data (a dual-layer Blu-Ray disc
can hold twice that).
 Blu-Ray discs are random-access devices.
 Blu-Ray discs are used in the same way as DVD-ROMs but,
since they can hold more data, they are also used to store
very high-quality, high-definition (HD) video.
Recordable Optical Discs
 Recordable optical discs can have data written onto them
(‘burnt’) by a computer user using a special disc drive (a
disc ‘burner’).
 CD-Recordable (CD-R) and DVD-recordable (DVD-R) discs
can have data burnt onto them, but not erased.You can
keep adding data until the disc is full, but you cannot
remove any data or re-use a full disc.
 CD-ReWritable (CD-RW) and DVD-ReWritable (DVDRW) discs, unlike CD-Rs and DVD-Rs, can have data
burnt onto them and also erased so that the discs can
be re-used.
Solid-State Storage Devices
 The term ‘solid-state’ essentially means ‘no moving parts’.
 Solid-state storage devices are based on electronic
circuits with no moving parts (no reels of tape, no
spinning discs, no laser beams, etc.)
 Solid-state storage devices store data using a special type
of memory called flash memory...
USB Memory Sticks
 Memory sticks are non-volatile, random-access storage
 Each of these small devices has some flash
memory connected to a USB interface. Plug it into your
computer and it appears as a drive.You can then add files,
erase files, etc.You can use it to move any type of
file between computers.
 Flash memory used to be very expensive, but in recent years
it has become much cheaper and you can now buy a 16GB
memory stick for just a few dollars.
Memory Cards
 Many of our digital devices (cameras, mobile phones, MP3
players, etc.) require compact, non-volatile data storage.
Flash memory cards provide this and come in a variety of shapes
and sizes.
 One of the most common formats used by digital cameras is the
SD Card. The cards store the digital images taken by the camera.
Mobile phones contain a Subscriber Identity Module (SIM) card
that contains the phone’s number, the phonebook numbers, text
messages, etc.
 Many phones also have extra memory cards to store music, video,
photos, etc.
Backing Up Data
What is a Backup?
 A backup simply means making one or more copies of
your data.
 For example, if you have a folder of photos stored on the
hard-drive of your laptop, you might back them up by
copying them to a CD-R.
Why Backup Your Data?
 If you delete a file by accident or your computer breaks or
your laptop is stolen, or your business burns to the ground,
having a backup copy means that you have not lost your
precious data. You can recover your lost files and
continue working.
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