Chapter 2 Hardware and Software

CHAPTER 2
HARDWARE AND SOFTWARE
Anjan Mahanta
anjan.mahanta@satreephuketipc.com
1
Cambridge International AS and A Level IT

SYLLABUS
Hardware
● define the term hardware
● evaluate internal hardware devices (including: central processing unit (CPU),
motherboard, random access memory (RAM), read only memory (ROM), graphics
card, sound card, hard disk drive (HDD), solid state drive (SSD))
● evaluate external hardware devices (including: cloud, monitor, keyboard, mouse,
printer (laser, inkjet, dot matrix, plotter), speakers, camera (digital, video),
webcam, scanner, magnetic ink character reader (MICR), optical mark reader
(OMR), optical character reader (OCR), barcode reader, pen drive, portable hard
disk drive, blue-ray disk drive, memory card)
2

SYLLABUS
Hardware
● explain the purpose of storage devices
● evaluate storage devices (including: magnetic tape drive, optical, hard disk drive
(HDD), solid state drive (SSD))
● explain the purpose of input and output devices
● evaluate different input, storage or output devices for a given task
3

SYLLABUS
System, application and user interface software
● define the term software
● evaluate types of software (system software and application software)
● explain the purpose of system software (including: compilers, linkers, device
drivers, operating systems and utilities, interpreters)
● evaluate application software (including: word processing, spreadsheet, database
management systems, control software, measuring software, applets and apps,
photo editing software, video editing software, graphics manipulation software,
communications software, web authoring software)
4

SYLLABUS
System, application and user interface software
● evaluate application software for a given task
● evaluate the characteristics of different types of user interface (including:
command line interface, graphical user interface, dialogue interface, gesture
based interface)
● evaluate the use of colour, layout, font size, quantity of information and controls
when designing a user interface
● evaluate mental models and how they can be used when designing a user
interface 5

SYLLABUS
Utility software
● define utility software
● describe the role of different utility software (including: anti-virus, back-up, data
compression, disk defragmentation, formatting, file-copying, deleting)
6

HARDWARE
Hardware is categorised into input, output and storage
devices.
● Input devices allow data to be sent to a computer
(e.g.keyboard)
● Output devices allow the communication of
data/information from a computer(e.g. monitor).
● Storage devices store data on to a storage medium
so that it can be used at a later time.
7

INTERNAL HARDWARE DEVICES
CENTRAL PROCESSING UNIT
● The ALU performs calculations and
logical operations.
● The CU runs the fetch - execute
cycle which fetches instructions
from memory and executes them.
● Input data is taken from input
devices (such as a keyboard) or
storage and processed by the CPU,
which produces output data that can
be stored or sent to an output device
(suchasamonitor). 9

● CPUs usually consist of multiple cores.
● Each core is a separate processor, so a
quad-core CPU has four processors.
● Processors are measured by the number of
instructions they can process per
second(hertz).
● A 3GHz (gigahertz) processor can process
upto 3 billion instructions per second.
10

11

MOTHERBOARD
● The motherboard is a printed circuit board (PCB)
which connects the main components of a
computer.
● Some of these components may be an integral part
of the motherboard. Such components can include
Universal Serial Bus (USB) ports, a network port
and an integrated graphics card.
● A motherboard will always include the main bus
which is used to transfer data between hardware
components.
12

HARDWARE
MOTHERBOARD
● Other hardware components can be
connected directly to the motherboard,
including random access memory (RAM),
the CPU and expansion cards.
● Expansion cards offer additional
functionality, such as enhanced graphics
processing and additional USB ports.
13

RANDOM ACCESS MEMORY - RAM
● Random access memory (RAM) is memory that is used to store currently active
programs and data. The more RAM that is available to the computer, the more data
and programs can be used at the same time.
● This is particularly important in multitasking environments, when several programs
maybe open at the sametime.
● When the RAM becomes full, programs or data that are no longer active will be
removed to make space for new programs or data. If the RAM becomes full and there
are no inactive programs or data to remove, then an area of secondary storage
(e.g.hard disc drive (HDD) or solid state drive(SSD)) known as virtual memory is used
to expand the amount of memory available to the CPU. 14

RANDOM ACCESS MEMORY - RAM
● Virtual memory is very slow because secondary storage access times are thousands
of times slower than RAM access times.
● RAM is volatile, which means the content of the memory is lost if there is no power to
the RAM. When you are using a computer and experience a power cut, this is why the
data you are currently using is lost unless it has recently been saved to secondary
storage.
15

READ ONLY MEMORY - ROM
● Read only memory (ROM) is memory that, once it has been
written to, can no longer be changed. It is permanent and it
is non-volatile, which means that when there is no power
to the computer, the contents of the ROM will be retained.
● This is because it is powered by a small long-life battery.
● ROM is also used in small devices such as calculators
where there is only one program or set of instructions.
16

GRAPHICS CARD
● A graphics card is also known as a video card, display
adapter or graphics adapter. It is a printed circuit board
that connects to one of the motherboard’s expansion slots.
● Its purpose is to generate the signals needed to display the
output image from the computer.
● Often the graphics adapter is integrated into the
motherboard and does not require a separate card.
However, by using a separate card, the graphics
performance can be improved as a separate processor can
be used for graphics (a graphics processing unit). 19

GRAPHICS CARD
● Graphics cards include a variety of options for output.
Standard video graphics array (VGA) output to a monitor is
achieved through the RGB port which transmits red, green
and blue signals to the monitor in an analogue format.
● High definition display is achieved through a
high-definition multimedia interface (HDMI) port.
● Another option is Digital Video Interface(DVI) which
supports high resolution displays using digital signals.
20

SOUND CARD
● The purpose of a sound card is to generate the signals needed to
output sound from the computer to a speaker or set of speakers.
● It is often an integrated part of the motherboard and will include
a single output for audio (greensocket), a single input for a
microphone (red socket) and a single input for line level
devices(bluesocket).
● If higher quality or surround sound is required, then it is usually
necessary to have a separate sound card which connects to one
of the motherboard’s expansion slots. This will enable multiple
outputs for front, rear, centre and sub-woofer speakers. 21

HARD DISK DRIVE
● Hard disk drives are magnetic media that store and retrieve digital
data. Its architecture is rigid rapidly rotating disks, or platters, held
in place by spindles.
● The platters are not magnetic but are coated with magnetic
material.
● Magnetic heads on actuator arms move over the platter surface to
read and write binary data bits by detecting changes in
magnetization on the platter.
● This is random access storage that does not require sequential
blocks to work. Disks are of course non-volatile and will not lose
stored data when the drive powers off.
23

HARD DISK DRIVE
● Modern HDDs spin from a low consumer speed of 4200 revolutions per minute
(rpm) to enterprise-grade 15K rpm.
● HDDs usually have two motors: one for the spindle to spin the disks and the
motor that positions the arms and read/write heads.
24

HARD DISK DRIVE CHARACTERISTICS
High capacity and performance are primary HDD characteristics, with
reliability a close second.
Capacity
● The industry measures capacity in powers of 1000, so a 1TB drive stores 1000GB.
Not all this room is available for user data storage thanks to the file system and
computer OS, and on most disks reserved space for RAID operations or other
recovery options. The OS will report available storage correctly to the user.
● Commercial available HDD capacity varies wildly from a few hundred GBs to 12TB
for enterprise drives.
26

Performance is calculated by three measurements: average access time, average latency,
and average data rate.
● Access time is the time it takes for the disk drive to move the heads to a track to read or
write the data. Access time includes the actual seek time (how long it takes the heads to
get to the right track), rotational latency, and sufficient time to complete command
processing.
● Rotational latency is the time it takes for the requested sector to move under the head.
Latency is calculated from seek time and the rpm of the spinning disk and is measured in
milliseconds. Typical rotational speeds range from 6.25 ms at 4800 rpm to 2 ms at 15K
rpm.
● Transfer rate is how fast the data is transmitted to and from the read/write heads. It’s
usually described in as megabytes per second (MBps).
27

Reliability
● HDD reliability does not directly correlate to HDD failures. Many external factors
can cause a disk failure, including power loss, wildfire or floods, magnetic
interference, malware, dropping a drive (it happens), or environmental
contamination that causes a head crash.
● HDD reliability is concerned with internal threats to the HDD, including equipment
failures, data errors, and head crashes.
28

● The hard disk drive consists of two main parts: the device that is the electronics
which store the data, and the disk that is the medium on to which the data is
stored.
● The device (or drive) includes a read-write head which sit sat the end of an access
arm and magnetises sectors on the disk (platter).
● There is usually more than one platter and therefore there will be several read-write
heads for each side of each platter.
29

● Each platter will have tracks and each track will be split into sectors.The tracks
that are in the same position on each platter form a cylinder.
● Wherever possible, a computer will attempt to store data on a single cylinder as
this requires the least access arm movement and the access arm is the slowest
part of the hard disk.
30

● Data stored on a hard disk is non-volatile.This
means that when the computer is turned off and
there is no power then the data will still be safely
stored on the hard disc.
● Hard discs can be internally connected to the
computer using a Serial Advanced Technology
Attachment (SATA) or Integrated Drive Electronics
(IDE) cable.
31

SOLID STATE DRIVE - SSD
● A solid state drive(SSD) is another secondary storage
device that is non-volatile.
● However, there are no moving parts and the data is
stored onto flash memory.
● It is also not necessary to store data in the same
cylinder in order to maximise access speed as the
data can be stored anywhere on the flash memory and
access speeds will not be affected.
● SSDs are also non-magnetic and so are not
susceptible to damage from to close, strong magnetic
fields.
33

SOLID STATE DRIVE - SSD
● They are used in higher performance
computers.
● A frequent compromise between speed,
capacity and price is to have a smaller SSD to
store the operating system and software (for
speed of access) and use a larger HDD to store
data.
● SSDs also require a lot less power than HDDs
and so are preferred in laptop and tablet
computers. 34

EXTERNAL HARDWARE DEVICES
CLOUD
● Cloud computing is a term that refers to anything where computing services are
hosted over the internet and not in the same physical location as the computer
being used.
● Data is stored on banks of servers that are accessed remotely. The physical
devices that store the data are owned by a hosting company rather than the
person or organisation using the data.
36

CLOUD
● When data is stored in the cloud, the hosting company takes all responsibility for
storing the data, managing the data, securing the data and backing up the data, so
that people or organisations no longer have to be concerned with this.
● As the data is stored remotely, it also means that it can be accessed at any time in
any place, so people do not have to be sitting at a specific computer or within an
organisation to access that data.
37

CLOUD
● The downside is that it takes longer to access the data as access times are limited
by the bandwidth available to the hosting company and other users who maybe
accessing data on the same servers at the sametime.
● It can also be quite costly to store large amounts of data on cloud storage.
● Some cloud storage options allow synchronisation to a computer, so the cloud
acts as a backup to the data stored on the computer. It also means that when
accessing the data from the allocated computer, access times will be faster than
accessing from cloud storage.
38

MONITOR
● Although not an essential part of every computer system, a monitor is certainly an
essential part of most computer systems as it enables the user to visualise the
output.
● It is connected to the computer using one of the ports on a graphics card. Monitor
sizes are measured diagonally and, apart from some very old ‘legacy’ monitors,
they now have flat screens which minimalise the amount of desk space that is
used and they are light enough to be mounted on a wall or a desk using a bracket
or on a shelf.
40

MONITOR
● A monitor will be limited by its resolution. This is the
number of pixels it can display and is measured
horizontally by vertically.
● For example, a high definition (HD) monitor can display
1920x1080 pixels. Some monitors also include a touch
interface (known as a touchscreen), which means that
the user can select items by directly interacting with the
display on the screen.
● These are often integrated into tablet computers and
mobile phones. 41

KEYBOARD
● A keyboard consists of a number of buttons which are used to input text or to
control parts of an interface.
● Its main limitation is the number of keys available.
● With a Roman alphabet, this isn’t too much of a problem because the alphabet only
contains 26 letters and ten digits.
● However, some alphabets, such as Arabic or Chinese contain many more
characters and so combinations of keys have to be used.
42

KEYBOARD
● A keyboard can be connected to a computer using a USB port, by wireless
Bluetooth or by other wireless technology.
● Keyboards vary in style and shape, and ergonomic keyboards are available to
provide more comfort and protection for the user from repetitive strain injury(RSI).
43

MOUSE
● A mouse is a pointing device which allows objects to be
selected and manipulated on the screen.
● The mouse controls a pointer which is displayed on the
screen.
● When the mouse is moved, the pointer moves and objects
such as menu scan be selected on the screen using one of
the mousebuttons.
● Like a keyboard, a mouse can be connected using a USB
port, by wireless Bluetooth or by other wireless technology.
44

PRINTER
● A printer produces a hard copy (printout) from a
computer usually on to paper.
● A simplex printer can print on a single side of paper,
where as a printer with a duplex unit can print on
both sides of each sheet of paper.
● Some printers include additional functions such as a
scanner.
45

LASER PRINTER
● A laser printer negatively charges a cylindrical drum which then attracts electrically
charged toner (powdered ink). The toner is then heated so that it melts onto the
paper.
46

INKJET PRINTER
● Cartridges full of ink in four different colours (black, cyan, magenta, yellow) are
used to ‘squirt’ ink onto the paper to form the required printout.
47

DOT MATRIX PRINTER
● Before laser and inkjet printers, dot matrix printers were
commonplace.
● They are a type of impact printer which means that the
printout is achieved by hitting the paper and the operation is
very noisy.
● This is done by a set of pins being driven onto a ribbon
which then transfers its ink to the paper.
● The main advantage of dot matrix printers is that they can
print on duplicate and triplicate paper (carbon copies) due to
the impact.
● They are also very robust printers and so last for a long time.
48

PLOTTER
● In the 1990s, a plotter used to ‘plot’ lines on to large
sheets of paper by moving the paper backwards and
forwards and drawing using pens to create vector
drawings.
● Today, plotters are inkjet printers designed to be used
with large sheets of paper, typically A2, A1 and AO. If
only black and white printouts are required, then
light-emitting diode (LED) plotters are much faster and
have cheaper running costs than inkjet plotters.
49

3 D PRINTER
● A 3D Printer is a manufacturing tool used to create
three-dimensional artifacts that have been designed on a
computer.
● 3D printers have a wide range of shapes, sizes, and types,
but in essence they are all computer controlled additive
manufacturing machines.
● Similar to how paper printers lay down ink in one layer to
create an image, 3D printers lay down or cure material layer
by layer to create a three-dimensional object.
50

SPEAKERS
54
● Speakers are used to provide sound output from a computer. These can be as
simple as a pair of stereo speakers or full surround sound.

CAMERA
55
● A camera can be used to capture still or moving images
(movies). When connected to the computer, the images or
movies can be transferred from the camera to the
computer’s storage.
● The images can then be viewed on screen, manipulated and
shared.
● A digital still camera is optimised for capturing still images
but usually has the capability of capturing movies too,
where as a digital video camera is optimised for capturing
movies but can also capture still images.

WEBCAM
56
● A webcam is a camera that is connected to the computer for
the purpose of capturing still or moving images while using
the computer.
● It will not be as high quality as a dedicated digital camera or
digital video camera. It will usually have an integrated
microphone for capturing sound.
● Its main purpose is for users to engage in online video chat
or video conferences. They can also be used as security
cameras.

SCANNER
57
● A scanner is used to capture two dimensional(2D) documents in the form of
an image.
● They perform a similar function to a digital camera but are specifically
designed to take close-up images of 2D documents.
● Flat-bed scanners can capture a full-colour image and save the image as a file
on the computer’s storage. If the image contains lots of text, then it is possible
to run optical character recognition(OCR) to recognise the text.
● Some flat-bed scanners include an automatic document feeder (ADF) that
enables documents with multiple pages to be scanned in one operation.

OPTICAL CARD READER
58
● An optical character reader (OCR) is a device that enables
characters on a document to be identified and understood
by the computer as letters, numbers, characters and
words.
● This isn’t really a device in itself, but is a scanner combined
with software that performs optical character recognition
(also OCR).
● The picture of the document is analysed and characters
are recognised by the software and turned into a
document so that the text can be searched or edited.

MAGNETIC INK CARD READER
59
● Magnetic ink is used to print numbers at the bottom
of checks. The numbers are printed using the
MICRE-13B or CMC-7font.
● The ink contains iron oxide which means that it is
easily detected when using a magnetic ink character
reader(MICR) and the characters can be
understood.
● It is important that mistakes aren’t made and so
MICR provides a much better level of accuracy than
OCR.

OPTICAL MARK READER
60
● An optical mark reader (OMR) detects the marks a multiple
choice document such as a multiple choice answer paper for an
examination.
● A scanner-like device is used to reflect a beam of light onto the
marked sheet and detect where the marks have been made.
● Software is then used to translate the position of the mark to the
information that it represents.
● OMR devices are only really suitable for multiple choice
responses as they cannot interpret letters that form words.

BAR CODE READER
61
● A barcode reader is used to detect the width of lines and gaps that
form a barcode.
● A laser beam is shone onto the barcode and a photodiode is used to
measure the amount of light that is reflected back. Blacklines will
not reflect any light but white gaps will.
● A barcode represents letters and numbers which usually identify
something, such as a book or other product. The barcode scanner
usually includes its own hard coded circuitry so that it can send the
letters and numbers directly to the computer without the need for
additional software.

PEN DRIVE
63
● A pen drive is a nickname for a USB flash drive. It is a small data storage device
about the size of a thumb which stores data on flash memory and includes an
integrated USB interface.
● The USB interface means that the flash drive is recognisable on all computers with
a USB port and therefore data can be transported easily between computers.
● Flash memory is very fast and so the limiting factor is the speed of the USB port. As
a flash drive does not have any moving parts it is safe to transport, although its size
means that it can be easily lost. It also does not rely on magnetising and therefore
is not susceptible to damage if it comes in contact with a strong magnetic field.

PORTABLE HARD DISK DRIVE
64
● Hard disk drives were introduced earlier in this chapter. As well as an
internal HDD, it is possible to have an external HDD.
● An external HDD can be connected to the computer using a USB or
External Serial Advanced Technology Attachment eSATA) port.
● An external HDD can store a lot more data than a USB flash drive, but it is
more susceptible to damage due to it having moving parts and its
vulnerability to strong magnetic fields.

BLU-RAY DISC DRIVE
65
● A Blu-ray disc is an optical storage medium. It is the same size and shape as
a compact disc(CD) and digital versatile disc(DVD).
● The Blu-ray disc was introduced because it can store HDvideo and
therefore a whole film can be stored on the Blu-ray disc.
● A single layer Blu-ray disc can store 25GB of data and a dual-layer Blu-ray
disc can store 50GB of data.
● This compares to a DVD which can store 4.7GB of data and a CD which
can store 700MB of data (or 80 minutes of audio).

MEMORY CARD
68
● A memory card is flash memory on a small card.
● They are typically used in digital cameras, digital video cameras and
mobile phones.
● They take up very little space so are well suited to fitting into a small
device, as well as being portable so that data can be transferred to a
computer.
● There are many different formats of cards, but most devices favour Secure
Digital(SD) and micro SDcards. MicroSD cards are only 15x11x0.1mm in
size.

REASONS FOR USING SECONDARY STORAGE DEVICES
70
● When creating a document, a user is likely to want to make changes to
that document in the future and therefore it is necessary to save it to
secondary storage.
● The user may want somebody else to edit or read the document and so it
will be saved to secondary storage to allow the person to do that.
● Users are likely to want to keep documents for archive purposes so they
can be referred to in the future.
● When using a database, each new record or change to a record will be
saved to the database in secondary storage.

REASONS FOR USING SECONDARY STORAGE DEVICES
71
● The user may want to backup the data so that a spare copy is available.
● Each program will be stored on secondary storage ready to be loaded into
RAM when the program is opened.
● The computer will use secondary storage to save a virtual memory file
which extends the amount of RAM available, albeit making the virtual part
of the memory very slow.

MAGNETIC TAPE DRIVE
72
● Magnetic tape is used for backing up and archiving data.
● Data is stored serially which means one item after another.
● The tape is wound through the tape drive and as it winds through data is
written to it.
● The low cost and high capacity of tapes makes them ideal for backing up
and archiving data because the data is simply stored in a sequential
manner.

MAGNETIC TAPE DRIVE
73
● When retrieving data, it does take a while to find the data that is required
because the tape has to be wound to the exact position where the data is
stored.
● This makes it unsuitable for everyday use. Backups and archives are not
intended for everyday use.
● If data does need to be restored from backup, it may take a while but it is
at least available when needed.
● If the whole of a computer’s secondary storage needs to be restored, then
this can be done by reading the tape sequentially.

MAGNETIC TAPE DRIVE
74
● Tapes are ideal for backing up the
whole of secondary storage for a
computer or server because they
can hold several terabytes(TB) of
data.
● In 2014, Sony developed a tape
capable of storing 185 TB of data.

OPTICAL
79
● Optical storage was introduced earlier in this chapter under the heading Blu-ray.
● In 2015, there were three main types of optical storage.

COMPARISON BETWEEN MAGNETIC TAPE & OPTICAL DRIVE
80
● Optical storage has been a popular medium to distribute software due to the low cost of each
disc, the fact that read-only versions of each disc exist and the low cost of posting them.
● Using recordable and rewritable versions of optical discs makes them suitable for backups
and archives.
● It is quicker to restore a single file from an optical disc backup rather than a tape backup
because the file can be accessed directly rather than having to read through a whole tape.
● This also makes optical discs more suitable for archived data because files can be found
quickly.
● The capacity of optical discs is much less than tapes, which means they are only suitable for
backing up a selection of files rather than the whole of secondary storage.

COMPARISON STORAGE DEVICES
83
●

COMPARISON STORAGE DEVICES
84
●

INPUT AND OUTPUT DEVICES
86
● Input devices allow data to be sent to a
computer (e.g. keyboard).
● Output devices allow the communication of
data/information from a
computer(e.g.monitor).
● When data is input into a computer, it is
processed and then either output from the
computer or stored for later use.
● Data that has been stored can also be
processed and then output from the
computer.

EXAMPLE
87
MULTIPLE CHOICE ANSWERING & PROCESSING

SYSTEM, APPLICATION AND USER INTERFACE
93

SYSTEM SOFTWARE
● Programs that are designed to maintain or operate the computer system are known
as system software.
● The software that operates the computer hardware is known as the operating
system.
● Programs that are used to maintain a computer system (e.g.anti-malware software)
are known as utility software.
94

OPERATING SYSTEMS
An operating system manages hardware by carrying out tasks such as:
● Allocating memory to software
● Sending data and instructions to output devices
● Responding to input devices such as when a key is pressed
● Opening and closing files on storage devices
● Giving each running task a fair share of processor time sending error messages or
status messages to applications or users
● Dealing with user logons and security.
96

DEVICE DRIVERS
● While the operating system can manage
the general instructions to deal with
hardware such as displaying graphics on a
screen, it requires the use of device drivers
to deal with specific makes and models of
hardware.
● A device driver is the software that comes
with an external hardware component and
sends customised instructions to that
specific component.
98

DEVICE DRIVERS
● By using common device drivers, software
applications are able to issue generic
commands such as ‘print’ to the operating
system without having to know the
different instructions required for every
different make and model of external
hardware components.
99

UTILITIES
● Utilities are part of system software. They are designed to perform functions
which maintain the computer system.
100

COMPILERS
● A compiler translates a program written in a high-level programming language in
to machine code which a computer can understand.
● The file containing the machine code is known as an executable file because it can
be executed by the processor.
● It can also be referred to as the object file. The original high-level programming
language file is known as the source file.
101

COMPILERS
● When a program is compiled, the whole source code is translated into the
executable file at once and can then be distributed to resellers, customers and
individual computers.
● As it is in an executable format, it can only run on operating systems for which the
compiler has translated it.
● For example, programs that have been compiled for Windows will not work on
Linux unless they are compiled again for Linux. The same situation exists with
mobile phone and tablet operating systems. 102

INTERPRETERS
● Interpreters also translate a program written in a high level programming
language into machine code, but use a different method, instead of translating
the whole source code at once, it is translated one line at a time.
● This can be less efficient than a compiler because it takes time to do the
translating as the program is being executed and also because statements
within programming loops (e.g. FOR, REPEAT, WHILE) have to be analysed
each time round.
103

INTERPRETERS
● Interpreters are often used to translate
macros or application-based script languages
(e.g. Visual Basic for Applications), which can
be particularly useful when a document
needs to be opened on a variety of operating
systems.
● Interpreters are also used when testing
programs so that parts of the program can be
executed without having to compile the
whole program. 104

DIFFERENCE BETWEEN COMPILER & INTERPRETER
105

DIFFERENCE BETWEEN COMPILER & INTERPRETER
106

LINKERS
● Computer programs often consist of several modules (parts) of programming
code.
● Each module carries out a specified task with in the program.
● Each module will have been compiled into a separate object file.
● The function of a linker(also known as a link editor)is to combine the object files
together to form a single executable file. 108

LINKERS
● In addition to the modules used,the program may make reference to a common
library.
● A common library contains code for common tasks that can be used in more than
one program, such as mathematical functions, memory management, progress
bars /output. The linker is able to link modules from a library file into the
executable file,too.
● Not all modules are always needed and a linker is able to select which modules
will form part of the executable file.
109

APPLICATION SOFTWARE
● Programs that are intended for productivity or to carry out at ask for the user are
known as application software.
● Examples include word processor, games, web browser and graphics software.
● On a mobile phone or tablet, this type of software is usually referred to as an app.
111

WORD PROCESSING
● The function of a word processor is to primarily process words.
● It is therefore appropriate for tasks such as:
○ Writing a letter
○ Producing a report
○ Producing course work
○ Creating a menu
○ Mail merging
○ Writing a book
112

WORD PROCESSING
Features of word processing software include:
Tables, Headers and footers, Footnotes and
endnotes, Sections, Formatting text, Styles
Spellchecker, Bullets and automatic numbering,
Automatic contents page,
Tracking changes, Frames for images, Text
alignment
113

SPREADSHEET
● Spreadsheet software is used mainly for performing calculations and modelling.
● Spreadsheets are often used for financial and statistical information.
● Spreadsheets work on the basis of input-process-output whereby data is input,
then formulae and functions process that data to generate an output.
● When input data changes, the output data automatically changes because the
formulae and functions are automatically recalculated.
● This allows users to experiment with values and ask 'What-if questions such as'
What will happen if we try to sell another 10000 cars this month?’
● Spreadsheets contain cells which form the intersection of rows and columns.
116

DATABASE MANAGEMENT SYSTEM
117

DATABASE MANAGEMENT SYSTEM
A DBMS can provide features including:
● Data entry screens/forms for inputting data
● Filters and queries for selecting data that meets specified criteria
● Reports for displaying information in an easily readable format
● Graphs for analysing data
● Security features so that users can only access the parts of the database they
have been authorised to access
● Relationships to link related tables 118

GRAPHICS MANIPULATION SOFTWARE
The features included in graphics manipulation software vary depending upon the
complexity of the software.
Features for both bitmap and graphics manipulation software can include:
● Drawing shapes
● Changing the canvas size
● Resizing the image
● Adding layers
● Adding text to an image
● Selecting a colour based on picking an existing colour
119

Feature for bitmap graphics manipulation software can include:
● Filling an area with a colour
● Moving part of the image
● Resizing part of the image
● Erasing parts of an image
● Cloning parts of an image
● Softening (blurring) and sharpening an image
120

Features for vector graphics manipulation software can include:
● Filling a shape with colour
● Changing features of the border of a shape such as thickness and colour
● Combining shapes together into a group
● Moving a shape or group of shapes
● Resizing a shape or group of shapes
● Aligning objects
121

PHOTO EDITING SOFTWARE
Features of photo editing software include:
● Cropping parts of the photo
● Adjusting the brightness or contrast
● Resizing the canvas
● Removing red eye
● Changing the colour balance
● Cloning parts of the photo
● Identifying common areas of an image(e.g.background) using a'magic wand'tool
● Applying effects such as black and white or sepia
● Softening (blurring) and sharpening a photo
Photo editing software requires a large amount of RAM and complex operations can use up a lot of
processing time. 124

VIDEO EDITING SOFTWARE
Features of video editing software include:
● Importing or capturing raw video
● Clipping the beginning and end of a video
● Clipping sections within a video
● Adding titles to the beginning or credits at the end
● Overlaying videos with text or images
● Speeding up or slowing down footage
● Rotating footage using more than one video track
● Transitioning between clips(e.g.fade) add backing music, narration or other sound
● Using picture-in-picture to show two video clips at once
126

VIDEO EDITING SOFTWARE
Video editing software does have some down sides and these include:
● Using up a lot of processing time
● Requiring a large amount of RAM
● Importing raw video files can take a long time
● Encoding the final video takes a very long time
127

COMMUNICATIONS SOFTWARE
●
128

● Instant messaging software allows a user to communicate with another user by
sending text-based messages which are instantly sent and received.
● This can be a slow form of communication because of the need for typing, but some
people prefer it to having a real conversation.
● Audio conferencing allows users to speak and listen to each other in a similar way to
a telephone call.
● The main difference is that more than two people can be included in the conference.
This is usually achieved with voice over internet protocol (VOIP).
129

● A popular example is Skype.
● Making conference calls over the internet is usually free of charge but it does require
every participant to be logged on at the same time.
● During an audio conference it can be difficult to know whose turn it is to speak.
● Video conferencing expands upon audio conferencing by including real-time video of
the people involved in the conference.
● Email clients provide users with a larger range of features than web mail and enable
emails to be read and composed while offline.
● This can be useful when no fixed internet connection is available and 3G/4G
coverage is poor or non-existent.
130

FEATURES OF EMAIL CLIENTS
● Address book of contacts
● Ability to send and receive emails
● Signatures
● Prioritising of emails
● Delaying delivery of emails
● Delivery and read receipts
● Rules that can be applied to email messages (e.g.moving messages that contain a
specific subject to a specific folder)
131
● Using more than one email account at once
● Adding attachments to messages
● Digital signatures and encrypted messages
● Integration with a calendar
● Inviting contacts to a meeting in the calendar
and receiving responses.

WEB AUTHORING SOFTWARE
●
132

WEB AUTHORING SOFTWARE
● There are now many online content management systems and other tools that are
used to create and update websites, but some web developers sometimes prefer to
use offline web authoring software such as Dreamweaver.
● Web authoring software can be very complex to use because of the vast number of
configurations available for web pages, which is why using an online tool like
www.wix.com enables people with little experience of websites to create a site
quickly, although it can be difficult to customise it to exact requirements.
● Web authoring software gives the most flexibility and websites can be configured
exactly as required.
133

FEATURES OF WEB AUTHORING SOFTWARE
● common navigation bar
● ability to publish individual files or sites to a web server , preview of web pages
● viewing and editing in either what you see is what you get (WYSIWYG) view or Hypertext
Markup Language (HTML) code view or a mixture of both
● adding basic HTML features such as tables, horizontal lines and headings
● management of a webpage’s metadata
● designing templates that can be applied to all pages
● interactive features such as interactive buttons
● forms and form fields, validation of form fields 134

CONTROL AND MEASURING SOFTWARE
●
135

●
136

Control and measuring software is used in a wide variety of situations including
automated features of cars (e.g. automatic windscreen wipers), science experiments,
weather stations, pollution management and traffic lights.
137

Measuring software will measure values from sensors including:
● Pressure (amount of pressure applied)
● Moisture
● Temperature
● Windspeed
● Distance (measured by lasers)
● pH(acid/alkaline)levels
Control software will control devices such as:
● Lights
● Motors (e.g.to make windscreen wipers move)
● Speakers/sirens
● Heating
138

APPS
● An app is another name for a program. It is a piece of software that can run on a
desktop computer, over the internet, on a tablet computer or on a mobile phone.
● The most common reference to ‘apps’ is when referring to software that is
designed to work on mobile devices such as tablets or mobile phones.
● In this case, apps are optimised to work with touch screen interfaces and smaller
screens.
● They will provide essential features that can be carried out using the limited
interface of mobile devices, but often lack more complex features due to the need
for more processing power or accurate input devices such as a mouse and
keyboard.
139

APPLETS
● An applet is a small program that is designed to
carry out a specific task. An applet cannot run on
its own but must be executed from within
another piece of software.
● Applets are often known as add-ins, add-ons or
extensions. They can carry out additional tasks
that the original software is not capable of doing
or they can simplify tasks within the original
software.
140

DIFFERENT TYPES OF USER INTERFACE
● An interface is the boundary between two
systems.
● A user interface is the boundary between the
user and the computer system.
● A user interface represents the communication
between a user and the computer system.
● This communication can take many forms.
148

COMMAND LINE INTERFACE
● A command line interface (CLI) allows a user to enter text commands to which the
computer system will respond.
● The computer system will respond by producing results in a text format.
● CLIs use very little memory so they are useful in old systems or for maintenance
of very small systems/devices (e.g.engine management systems).
● They are also useful for technical users who need to carry out complex operations
which cannot be performed using more user-friendly interfaces.
● However, CLIs can be difficult to learn and use because users have to learn and
remember all the commands, and errors are easily made when entering those
commands. 149

DOS COMMANDS
● DATE
● TIME
● DIR
● CLS
150

GRAPHICAL USER INTERFACE (GUI)
● The most common type of interface that we use is a graphical user
interface (GUI).
● GUIs are found on desktop computers, tablet computers, mobile
phones, televisions, set-top boxes, photocopiers and some in-car
entertainment systems.
151

GRAPHICAL USER INTERFACE
(GUI)
GUIs can include some or all of the
elements
The acronym WIMP is commonly
used to remember these elements.
152

GRAPHICAL USER INTERFACE (GUI)
● Complex GUIs require a lot of memory to operate, but simpler GUIs can be
used where memory is limited.
● Although CLIs don’t require much memory, simple GUIs can be used
instead of a CLI in small systems such as embedded systems.
● It is common place to find simple web-based GUIs for the maintenance of
devices such as routers, switches and printers.
● GUIs are intuitive to use which means they are easy to learn because
commands are represented by pictures and menus provide options that can
be selected.
● However, they can be restrictive for some technical users who need to
carry out unusual tasks.
153

DIALOGUE INTERFACE
● A dialogue interface refers to using the spoken word to communicate with a
computer system.
● A user can give commands using their voice and the computer system can
respond by carrying out an action or with further information using a
synthesised voice.
● Dialogue interfaces are very popular with mobile devices, including mobile
phones and in-car entertainment systems.
● The main problem with this type of interface is the computer system’s ability to
recognise the spoken word. 154

GESTURE - BASED INTERFACE
● Gesture-based interfaces will recognise human motion.
● This could include tracking eyes and lips, identifying hand signals or monitoring
whole body movement.
● There are many applications of gesture-based interfaces, including gaming,
which have led to the development of other gesture-based interfaces.
● Gestures can be an essential form of interaction for some disabled users who
cannot use conventional input devices.
155

Important Features of User Interface Design
● Colour - Text must be legible. This means using a light font on a dark background or a
dark font on a light background.
● Layout - Careful consideration should be given to the layout of information, icons and
inputs on a screen. Similar information, icons or inputs should be grouped together.
● Font size - The standard size of font for reading is 11 or 12 points which is legible for
most users.
● Quality of information - If too much information is provided to a user, then this can
cause information overload and may mean that much of it is ignored.
● Controls - Controls are used on form. 156

Badly Designed Input Screen
160

ANTI-VIRUS
● Anti-virus software is sometimes referred to as anti-malware software as it deals
with other threats such as adware and spyware as well as viruses.
● It has two main functions. The first is an anti-virus monitor that is continually
monitoring the system for viruses and malware.
● If the anti-virus monitor detects any unusual behaviour or tell-tale signs of viruses
or malware then it will prevent them from being executed so they cannot cause
damage to files or programs.
● The second function is to check for viruses or malware that may already be on a
system. This is usually known as scanning the system.
165

BACKUP
● Backup utilities create a second copy of data and
programs that are in storage.
● A backup utility can be executed by the user, in
which case the backup takes place when the user
asks it to, or it can be scheduled to execute at a
predetermined time so that the backup takes place
automatically.
● The user is usually able to select which folders and
files will be backed up and can usually decide where
the backup will be stored.
166

DATA COMPRESSION
● Data compression utilities will reduce the original
size of files so that they use up less storage space.
● This can be achieved on a file-by-file basis or for a
set of files or even a set of folders.
● It will be slower to open the compressed file, but as
it is smaller it will use up less storage and can be
transferred from one location to another more
quickly.
167

DISC DEFRAGMENTATION
● As a hard disc gets used, files are kept together in storage on the same cylinder or
adjacent cylinders.
● As files grow in size, they use up more space on the disc and this may no longer be
on the same or adjacent cylinder.
● The problem with this is that when opening the file, the access arm of the hard
disc drive has to keep moving to different locations which makes opening the file
a slow process.
● When files are deleted, gaps are left on the disc. When all the cylinders have been
used, the only space to store files is within the gaps. If the gaps are not big enough,
then files have to be split across gaps, meaning that they become defragmented
168

DISC DEFRAGMENTATION
● A defragmentation utility will reorganise all the files so that each file is contiguous
(kept together).
● It will do this by moving fragmented parts of files and small files to free space on
the disc and creating space on whole cylinders or adjacent cylinders.
● It will then move the defragmented files to a place where the whole file is kept
together.
● This can significantly improve the performance of a computer system, especially if
program files have become fragmented and can be defragmented.
● https://www.youtube.com/watch?v=AtRIOUZuI2c
170

FORMATTING
● When a disc is prepared for first time use, it needs to be formatted.
● Formatting is the process of organising the tracks on the disc into sectors. Each
sector is where data will be stored.
● A used disc can also be formatted, in which case all data will be lost and the tracks
prepared again as if the disc was being used for the first time.
171

FILE COPYING
● Files can be copied using features within an operating system’s own interface.
However, this can be slow and options are limited.
● File-copying utilities enable users to have more control over which files are
copied and how they are copied.
● For example, a user may only want to copy word processing documents that are
within a series of folders and they may want all the files to be copied to a single
folder on the destination storage.
● It is also possible to synchronise files across multiple storage locations or even
multiple computer systems, so that when a change is made to a file in one
location, it will then be updated in all other locations. 172

DELETING
● Some files become locked by an operating system and it becomes almost
impossible to delete them.
● Deleting utilities can overcome this problem by deleting locked files and folders.
● When files are deleted using normal deletion methods, the data is still on the disc
although the user can’t see it.
● Therefore another function of deleting utilities is being able to delete files
permanently so that they cannot be restored or accessed.
● Some deletion utilities will remove temporary files that are no longer needed by
the computer system, or files that are no longer used but haven’t been deleted
when a program has been uninstalled or a user profile removed. 173

CUSTOM-WRITTEN VS OFF-THE_SHELF SOFTWARE
175

● When a client requires a software solution that will carry out a specific purpose
that is unique to their organisation, they will ask for the software to be written for
them. This is known as custom-written software because it is customised to the
needs of the client and will meet the requirements of the client.
● When software already exists and is purchased online or from a shop, it is known
as off-the-shelf software. The software will have been written for a general
purpose that is likely to be useful to a large market. Anybody can purchase the
software for a specified price.
176

177

178

COMPILERS AND INTERPRETERS
180

COMPILER AND INTERPRETER DIFFERENCES
181

Chapter 2 Hardware and Software

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