UNDERSTANDING INFORMATION TECHNOLOGY
This handout mainly deals with descriptions of data and information technology (IT) concepts
and terminologies. Why is it important to understand these technical terms?
There are several answers. First, many of these terms come up in later sessions, and therefore
need to be understood. Second, whilst you can, in theory, use computers without
understanding the technology, in practice the more you understand, the better. The best
racing drivers not only understand how to drive – they also understand how their cars work.
The same is true of the best computer users – the more they understand about information
technology, the more confident and competent they become. Third, understanding the
technical terms enables you to talk to or understand IT specialists.
1. INFORMATION TECHNOLOGY
Information Technology (IT): describes an organization’s computing and
telecommunications hardware and software technologies that provide automatic means of
handling and communicating information.
From the above definition, two possible divisions of IT could be drawn
- Computer (an electronic device that can process and store information) vs.
telecommunications (transmission of information between devices in different
locations).
- Hardware (the physical equipment) vs. software (the instructions)
It is the second categorisation that will be used for further exploration of IT below, together
with exploring the data that is handled by IT.
2. DATA REPRESENTATION IN INFORMATION TECHNOLOGY
A computer is structured in such a way that it operates with devices having only two states:
electric switches which are open or closed; electrical pulses high or not high; or magnetized
elements having one of two directions or polarities. These two states are represented by 0 or 1
and are referred to as BINARY DIGITS or BITS. Internally, the microprocessor recognizes
only these two symbols.
Human beings, however, use numbers, alphabetic and special characters when
communicating with the computer. Therefore, the computer needs to represent these decimal
numbers, alphabetic and special characters, using the binary digits “ 0’s” and “1’s” by using a
coding mechanism. The coding system defines the codes between a natural language and
binary symbols. For example, one of the most widely used coding mechanisms is ASCII
(American Standard Code for Information Interchange). Some examples of ASCII code are
Character ASCII
A 0100 0001
Q 0101 0001
+ 0010 1011
/ 0010 1111
0 0011 0000
9 0011 1001
In addition documents, photographs, drawings, recordings of sound or video, etc. – have to be
converted into this 0/1 data before IT can handle them. This conversion process is known as
digitisation (i.e. converting into the digits 0 and 1). Digitised information can be numbers,
text, images, audio or video. Digitisation is the key to making use of information technology:
once information has been digitised it can be subjected to a wide variety of manipulations and
transmissions that are not possible with manual systems. If information is not digitised, it
cannot be handled by IT.
3. TIME AND SIZE IN THE COMPUTER WORLD
The following table summarizes some key levels of time and size that are useful in describing
the speed and capacity of computers.
Time Size
Second Byte string of 8 bits
Millisecond 1/1000 second Kilobyte 1000 bytes
Microsecond 1/1,000,000 second Megabyte 1,000,000 bytes
Nanosecond 1/1,000,000,000 second Gigabyte 1,000,000,000 bytes
Picosecond 1/1,000,000,000 second Terabyte 1,000,000,000,000 bytes
4. DATA ORGANIZATION
When information is handled by information technology, it is often referred to as data, i.e. as
unprocessed information. We can most usefully think of data as being organised in a
hierarchy, as summarised in Figure 1.
Figure 1: The Data Hierarchy
Hierarchy Example
BIT 0/1
BYTE 10100001 (Letter A in ASCII)
FIELD John (NAME FIELD)
RECORD Number Name Sex Date of birth Course
001 John Male 12/09/78 OA553
FILE Number Name Sex Date of birth Course
001 John Male 12/09/78 OA5532
002 Anna Female 06/07/80 OA5532
003 Kim Male 04/12/74 OA5532
DATABASE
Course Classroom
File File
Student File Tutor File
- A BIT represents the smallest unit of data a computer can handle. A group of bits is called
a BYTE and represents a single character, which can be a letter, number or other symbol. A
grouping of character is called is called a FIELD.
- Field: an item of data about an entity.. Terms such as attribute or data element are
sometimes used to represent the same thing as a field. An entity is any person, place, event
or thing about which data is held. For example, in the figure above, “student” is an entity
about which data is being kept, other entities include course, classroom and tutor. A student
entity has several fields such as number, name, date f birth and so on. There should be a
primary key field that uniquely identifies each entity. For example, in the above figure,
student number would be a primary key field (not name since there could be two students
with the same name).
• Record: a grouping of related data elements that represents one specific entity. A record
forms a single entry in a file or database. Each record consists of several fields, and shares
field names in common with the other records.
• File: a collection of related records. In some situations, this is called a table. For
example, a student file in . Each file consists of several records.
• Database: a well-defined and managed collection of data. It may consist of a number of
related files, such as for example student, course, tutor, classroom files.
5. HARDWARE
Hardware: the physical components that make up any set of information technology. More
simply, hardware represents any part of information technology that you can drop on your
foot: the keyboard, monitor, disks, processors, printers, network cables, etc.
To provide an understanding of the different types of IT hardware, a process view of an
information system is relevant. Information systems involve the input, process, storage,
output and transmission of data and information. In an IT based IS each of these activities are
associated with a certain form of IT. Figure 2 provides a pictorial description of these
technologies.
Figure 2: Components of IT Hardware
SecondaryStorageStoredataadprograms•MagneticDisk•MagneticTape•OpticalDiskOutputTechnologyPresentdatainawayunderstandablebypeople•Monitor•Printer•PlotterInputTechnologyacceptsdataandinstructionforprocessing•Keyboard•Mouse•Scanners•VoiceinputTransmissionTechnologyControlthepassingofdataandinformationbetweentheinputoutputandstoragedevicesandusersatdifferentlcationsProcessTechnologyCPUALU:PerformArith.&
LogicalcomparisonsCU:control&directProcessingMemory:RAM&ROMStoredata&Instructionduringprocessing
Each of the above components will now be described in turn. In each of the sections that
follows, there are up to four sub-sections:
• Technologies in Common Use: these are technologies that typical users are likely to come
across in their use of computers; they also recur throughout the book.
• Other Technologies: these are technologies that are not so commonly-used; they may be
recent innovations or have only a specialised application.
• Other Relevant Definitions: these are technical terms that relate to the particular
technologies.
• Technology Trends: these provide a quick summary of general ways in which particular
types of technology are changing at the moment.
Input Technology
i. Input Technologies in Common Use
• Keyboard: used to input text or numerical data or commands to the computer.
• Mouse: a handheld device used to select objects or commands, or to draw images, via a
pointer on the computer screen.
• Scanner: converts both text and images from paper into a digital form. Digitising text or
marks on paper is often known as optical character recognition (OCR).
• Bar Code Reader: converts the printed lines of the bar code into digital form.
ii. Other Input Technologies
• Voice Recognition System: hardware that allows human speech to be understood and
converted into digital form
• Pen-based System: hardware that allows human handwriting to be understood and
converted into digital form by writing on a sensitive screen with a special pen.
• Touch Screen: a special screen that allows you to select on-screen objects or commands by
pointing to them directly with your finger.
• Digital Camera: a camera that records its pictures as a digital image rather than as a
photographic image on film.
iii. Input Technology Trends
The main trend in input technologies is towards direct input devices that are easy to use. It is
becoming easier, quicker and cheaper to digitise data. There is also an increasing ability to
digitise human outputs, such as speech and writing. This is helping increase the ability of
computers to work with non-Roman script languages such as those used in Asia, the Middle
East and some parts of Africa.
Process Technology
i. Process Technologies in Common Use
• Central Processing Unit (CPU): the core of any computer, that manipulates data by
performing arithmetic computations on the computer's 0/1 data, and which also controls
the other parts of the computer system. Often called the computer chip because it is made
from a single slice, or chip, of silicon. It works by following the instructions specified in
the computer's software programs (see section on software for further explanation).
ii. Other Relevant Definitions
• Megahertz (MHz): one million cycles per second. A measure of the speed of the 'internal
clock' of the computer's CPU that synchronises the work of the CPU components. In very basic terms, the faster the speed of the clock (i.e. the more megahertz), the faster the
computer can process data.
• Mips: million instructions per second. A measure of the speed of processing of the CPU.
iii. Process Technology Trends
The overall trend is for cheaper, smaller, faster, more reliable processors. This has been
partly based on developments in CPU component technology (the bits that make up the CPU).
There have been five major generations (Table 1) in the history of processors development
and over the past 40 years processing power has doubled approximately every 12 to 18
months, a phenomenon commonly known as Moore’s law.
Table 1: Generations of Processor Technology
Generation Technology Typical Cost
First generation Valves (Vacuum Tubes) US$2,500,000
Second
generation
Transistors (invented in 1947) US$250,000
Third generation Integrated circuit (IC) grouping an entire
electronic circuit of several transistors and
other components onto the same semi-
conductor chip/silicon wafer (invented in
1958)
US$25,000
Fourth generation Large Scale IC (LSCI) Microprocessor
grouping all processing functions onto a
single chip (invented in 1971)
US$2,500 at
first
US$250 now
Fifth generation Very Large Scale Integrated Circuits
(VLSIC)
A further trend, for example within microprocessors, has been the emergence of global
standards. Intel is a US company that produces the CPUs for many microcomputers
throughout the world. It has developed a series of generations of microprocessor CPUs, with
each generation being faster (because of faster clock speeds) and more powerful than the
previous generation. When purchasing microcomputers, you often need to understand the
latest generations available.
Table 2: Generations of Intel Microprocessors
Intel Microprocessor
Generation Name
Date of First Use Clock Speed Range
(MHz)
4004 1971 0.108 (108 kilohertz)
8080 1974 2
8086 1978 4.47
286 1982 8-28
386 1985 16-33
486 1989 20-133
Pentium 1993 66-200
Pentium Pro 1995 150+
Pentium II 1997 266+
Pentium III 1999 450+
Pentium 4 2000 1500 (1.5 Gigahertz)
Itanium 2001 1500+
To give a further idea of change, the 8086 chip contained 29,000 transistors. Pentium 4 chips
contain about 42 million transistors.
Storage Technology
Storage technologies are normally classified as primary and secondary. While the primary
storage refers to the computer memory, other technologies that are used for keeping a
permanent record of data, information and instruction after (and before) the computer is used
are commonly known as secondary storage technologies.
i. Storage Technologies in Common Use
Primary Storage
• Memory: retains or stores electronic representation of programs or data inside the
computer. Broadly speaking, there are two types of memory chips, which are used for
different purposes: Read Only Memory (ROM) and Random Access Memory (RAM).
- RAM (random access memory) on which you can store (write) and retrieve (read) data
and instructions, and which loses all data when the computer's power is turned off. All
other storage hardware retains its data even when the power is off. RAM is used for
holding data or instructions temporarily just prior to, or just after, processing by the
CPU and forms the main workspace of a computer. Normally, a computer’s memory
capacity refers to the RAM size and is one of the factors that affect the speed of the
computer
- ROM (read-only memory) holds permanent data or instructions built into the chip at
the factory, and may be read (retrieve data or instructions) from but not written to -that
is, you cannot change the instructions on them. ROM, as its name suggests, cannot
store any additional data, but it retains its existing data even when the power is off.
ROM is typically used for performing specific tasks such as helping start up the
computer when it is switched on.
Secondary Storage
• Hard Disk: a set of rotating inflexible disks covered in magnetisable material, and
typically built into the computer. Disks are faster than tape because each surface has a
floating electro-magnetic reading/writing 'head' that can move very quickly to any location
on the disk. Disk is slower (though cheaper per byte stored) than computer memory and is
used for permanent storage of files and software programs.
• Floppy Disk: a single rotating flexible disk covered in magnetisable material, held inside a
plastic case (often blue or black). It can be put in and out of the disk drive that is held
within the computer box. The disk drive houses the motor that turns the floppy disk and
the reading/writing head. The most commonly-used format of floppy disk is the 31/
2-inch
size. Floppy disks hold much less data than a hard disk but have the advantage that they
can easily be moved from one computer to another.
• CD-ROM: compact disk read-only memory. An optical disk similar to those used for
music, from which data is written and read by a laser beam. Data is stored by burning
away (0) or leaving (1) tiny reflective spots on the CD. CDs can hold large amounts of
data (equivalent to 200,000 typed pages) but, like other ROM, can only be used to read
pre-recorded data rather than for storage of additional data. They are mainly used for
distributing large files such as software programs, books or audio and video data.
• DVD-ROM: digital versatile disk read-only memory. Like CDs, these are optical disks, but
they have a capacity at least seven times greater.
• Magnetic Tape: plastic tape covered in magnetisable material. In simple terms, all
magnetic media (i.e. both tape and disks) store data by magnetising (1) or demagnetising
(0) tiny areas on the brown iron oxide surface. To access an item of data on tape, you have
to wind the tape all the way through to the relevant spot. Tapes are therefore relatively
slow but can hold large amounts of data quite cheaply and are therefore used mainly for
archiving or 'backing up' large files.
ii. Other Storage Technologies
• WORM: write once, read many optical disk. A special type of compact disk and disk drive
that can write data onto a blank CD once, and then read it off many times.
• Erasable Optical Disk: a special type of compact disk and disk drive that allows data to be
written, read and erased just as with a conventional floppy disk (except much more costly
and with a far higher storage capacity). Because they generally use a combination of
magnetic and optical material, these are often known as magneto-optical disks. CD-RW
(compact disk rewriteable) is one example.
• Smart Card: combined memory and processor on a credit card-sized device. Can be used
to hold personal details (e.g. education records) or ‘electronic money’.
iii. Other Relevant Definitions
• Storage Capacity. is measured in terms of the bytes the storage technology stores. While
most computers have RAM size measured in megabytes, storage technologies with
Gigabytes capacities are common. For example a typical floppy disk can store around 1.44
MB; in other words 1,440,000 bytes of data but in most personal computers the hard disk
capacity is measured in gigabytes.
• File: when you do some work on a computer and store that work on a disk, the result is
called a 'file'. Notice that this a rather different and more general definition than that given
earlier for files connected with a database.
• Filename: every file stored on your disk needs to have a name (preferably one as
meaningful as possible rather then FRED1, FRED2 and so forth). The computer program
you are using may well add something to the end of the name (the filename extension), for
example .DOC or .TXT for a text document.
• Directories and Sub-directories: a filing cabinet used for storing documents is divided into
drawers, and each drawer is divided into folders. This allows you to quickly locate any
document you want without having to look through every document you own. In the same
way, a hard disk used for storing electronic files is divided into 'directories', and each
directory is divided into 'sub-directories'. For example, your hard disk might have one
directory for word processed documents, another for spreadsheet files, another for database
files, and so on. The word processing directory might have one sub-directory for project
report documents, one for external correspondence, one for internal correspondence, and
so on.
iv. Storage Technology Trends
Storage technology is becoming cheaper, quicker, smaller, and higher capacity. The trend is
towards massive capacities using optical media. In addition, because of the increase in the
volume of data that organizations maintain, businesses are building a new form of
infrastructure called Storage Area Networks (SANs) that connect different storage
technologies and enable users to access and share data across globally distributed businesses
and applications. Moreover to serve the storage needs of businesses a new form of service
providers known as Storage Service Providers (SSP) are mushrooming. Organizations rent
storage space from SSPs and pay for the service pretty much the same as they rent physical
warehouse for stocking inventory.
Output Technology
i. Output Technologies in Common Use
• Monitor: a device that produces an image in much the same way as a television. The
image on the monitor is made up from thousands of tiny dots, known as pixels (short for
'picture elements'). The more of these dots there are, the higher the quality of image or
resolution produced by the monitor. The monitor is sometimes referred to as the screen,
particularly on portable computers where the screen is flat. Flat screens use a different
display technology, generally based on liquid crystals like those used in calculators or
digital watches.
• Printer: a device that produces a paper-based output of text or images. There are a number
of ways printers can be classified,
- Impact vs non-impact printer-a classification based on the method used to place the
image on the paper or form the character on paper. In impact printing the image is
transferred onto paper by some type of mechanical print heads striking paper in the
manner used by typewriters. Printers in this category include, dot-matrix, and line
printers. Non-impact printers, on the other hand, use a variety of non-mechanical
printing manners such as ink jets ('spitting' a tiny piece of ink through a nozzle onto the
paper) or low-power laser or electrostatic techniques (as in a photocopier) to form
characters on a paper. Printers in this category include, ink-jet and laser printers.
- Printers can also be classified into three on the basis of their mode of printing:
character printers, line printers and page printers. Character printers produce printed
output by consecutively printing each character at a time to produce a line of
information. Line printers, as their name implies, print a complete line at a time. Page
printers (also called laser printers) use laser and electro-photographic technologies to
assemble and print a page at a time.
As you move from dot-matrix to ink-jet to laser then, in very general terms, the printing
becomes: faster, higher quality, and more expensive.
• Speakers: produce sound (audio) output. Speakers generally require a sound card (a
special circuit board that creates sound) to be inserted into the computer for them to
function.
ii. Other Output Technologies
• Speech Synthesis: produces an output of computer-generated speech.
• Plotters: output devices for producing (drawing rather than printing) graphs and graphical
diagrams. Many of them have several pens so that multi-coloured output can be produced
by using a different coloured ink for each pen.
iii. Other Relevant Definitions
• Dot Pitch: a measure of how close together the dots on a monitor screen are: the smaller
the dot pitch, the higher the image quality.
• Dpi: dots per inch. A measure of how many ink dots the printer uses to create the image
on paper: the more dpi, the higher the image quality.
• Printer Speed: measured in terms of the number of character or line or page a a printer
prints per minute.
• Card: a small circuit board of components performing some specialised function that can
be inserted into a slot on the main circuit board (the motherboard) housed within the
computer.
iv. Output Technology Trends
It is getting easier and quicker to produce output using new technologies, which are
increasingly producing higher quality and colour outputs. There is also a trend towards
multimedia outputs. Multimedia means the ability to produce output in a variety of media
including text, sound (including speech), graphics and video. A multimedia computer is one
that has a DVD-or CD-ROM, sound card, speakers, video card and good quality monitor in
addition to other hardware. This is now the norm for office computers.
Transmission Technology
It is possible to identify two types of transmission technologies. The first is that used for the
passing of data and signal among the different components of a computer such as from input
device to the processor and then to out put devices and the second is the transmission of
information among different computers and geographically dispersed users.
i. Transmission Technologies in Common Use
• Bus: hardware paths that transmit data inside the computer from one component to
another, e.g. from the memory to the processor.
• Wire: copper wire that transmits data. Comes in two forms: twisted pair (like a traditional
telephone wire) and coaxial cable (like a television aerial wire).
• Optical Fibre: a cable made up of thousands of strands of transparent glass fibres, each the
size of a human hair. These fibres transmit data in the form of pulses of light from a laser
rather than as an electric signal, as in wire. Optical fibres are generally more costly than
wires but can transmit greater amounts of data.
• Microwave: transmission of data as high frequency radio waves directly between earth-
based microwave dishes. Microwaves travel in a straight line, limiting the distance
between microwave dishes to around 30 miles (because the Earth's curve gets in the way).
• Satellite: transmission of data using microwaves from one earth site to another via an
orbiting satellite. Because satellites are high above the Earth, they can transmit across vast
distances. They are the most costly form of transmission technology but, as costs fall, they
are becoming more competitive with microwave even for short distance transmission.
ii. Other Transmission Technologies
• Packet Radio: the use of ordinary radio waves to transmit packets (small blocks of digital
data). These systems are cheap and suitable for covering large distances when relatively
small amounts of data need to be transmitted.
• Cellular Transmission: the use of the cellular/mobile phone network for data transmission.
These systems provide an easy form of mobile transmission in areas where a cell phone
network already exists.
• Infrared Transmission: the use of infrared light to transmit data. This method is used
within offices for portable devices, e.g. to transmit data from a portable computer to a
printer.
iii. Other Relevant Definitions
• Bps: bits per second. A measure of the speed at which data is transmitted. There is a set
of internationally agreed CCITT (Consultative Committee for International Telephone and
Telegraph) standards for bps rates. Standard V32, for instance, means transmission at
9,600 bps, and standard V34Plus means transmission at 33,600 bps.
• Bandwidth: a measure of the data-carrying capacity of a transmission channel.
• Signal: the way in which data is transmitted along the communication channels. There are
two forms of signal:
-Analogue Signal: a continuous wave, like that of the human voice.
-Digital Signal: a series of on-off pulses corresponding to the 1s and 0s of digital data.
Radio and telephone channels have traditionally only been able to carry analogue and
not digital data. However, this is changing with more and more transmission channels
able to carry digital data: computer buses, most new phone lines and new mobile
telephony, optical fibres and packet radio all fall into this category.
iv. Transmission Technology Trends
Transmission technologies are becoming smaller, cheaper and faster, with greater data-
carrying capacity. They are also allowing less interference or loss of signal ('attenuation').
There is increasing use of 'wireless' technologies, and there is increasingly globalised
connectivity being provided.
Telematics Technology
• Telematics: the linking ('convergence') of computer and telecommunications technology.
i. Telematics Technologies in Common Use
• Computer Network: two or more computers linked together so that data can pass between
them. There are two principle types of network:
-Local Area Network (LAN): a network covering computers in a single building. These
are sometimes based around a PBX: private branch exchange. This is a computerised
telephone switching system for the organisation that handles both voice and digital data.
Wide
Area Network (WAN): a network covering computers in more than one building,
typically in different cities or countries. There are thousands of different wide area
networks around the world. Many of these are linked to each other through the
'network of networks' known as the Internet. Whereas LANs normally use connections
bought and operated by the user organisation, WANs rely more connections provided
by telecommunications companies. These connections may be either the switched lines
available to the general public, or dedicated lines leased for sole use of the user
organisation.
• Network Node: any device connected to a network, such as a computer, printer, etc.
• Modem: MOdulator DEModulator. As already described, computers use digital data
whereas traditional telephone lines cannot, because they were built to carry the continuous
wave form, analogue signals of the human voice. To transmit computer data over
traditional phone lines, you therefore require a modem. This is an electronic box or circuit
board card that sits between the digital signals that a computer can understand and the
analogue signals that the telephone lines can carry. Where traditional telephone lines are
supplanted by transmission systems that can cope with digital signals, modems are no
longer required.
• Network Interface Card (NIC): a circuit board card that is installed in the computer to
make the physical connection between a computer and a network that can accept digital
signals. The card has a socket at the back to which you link up the network cable.
• Fax: combined scanner and printer that converts text and images on paper into digital
form, transmits the data to another fax, which reconverts the digital data back to text and
images on paper. Fax thus combines input, output and transmission technology. It is
increasingly used in the form of a fax card inserted into a computer, for which the start and
finish are a digital rather than paper-based document.
• Interconnection devices: there are many devices that connect network components. They
include hubs that connect nodes to a LAN; bridges that interconnect LAN segments; and
routers that determine the optimum network route for data traffic.
ii. Telematics Technology Trends
There is increasing convergence of computers and telecommunications through increasing
connection of computers to ever-larger telecommunications networks (and through increasing
use of computers to run networks). At the beginning of the 1990s, the majority of computers
in the world were 'stand-alone'. Today, the majority of computers in the world are networked.
There is also an emergence of global standards defining how data is passed around networks.
Computer Classifications
Traditionally, on the basis of size, processing speed and cost, computers were classified into
four: Super, Mainframe, Mini ad Micro
- Supercomputers are very sophisticated and powerful computers that can perform very
complex computations extremely rapidly.
- Mainframes (also known as legacy systems) are largest category of computers
typically serving the needs of organizations with large-scale data processing activities
but whose use has declined since the 1980s.
- Minicomputers (sometimes called midranges) typically serve the needs of dozens or
hundreds of users. One might be sufficient for an organisational department. First used
in the 1970s.
- Microcomputer: a small computer that would fit onto a desktop. When first used, one
microcomputer served the needs of one person. They are therefore also known as
personal computers (PCs). However, as microcomputers have become ever more
powerful, they have become able to support the work of several individuals, leading to
the apparently contradictory existence of 'multi-user personal computers'. First used in
the 1980s.
Other computer sizes include
- Workstation: a powerful PC with a high-resolution monitor for use by a specialist
professional, such as a designer, engineer or scientist. It is seen as lying between the
midrange and microcomputer categories.
• Portable Computer: a PC that can be carried around, sometimes known as a laptop if it
can fit on your lap, or a notebook computer if it is the size of an A4 notebook. Smaller
still are palmtop computers. Handheld computers that use pen input and can recognise
handwriting are called personal digital assistants (PDAs).
Nowadays the distinction between microcomputers, minicomputers and mainframe is
becoming increasingly blurred, as microcomputers become available with the power, which
mainframe computers had only a few years ago, and the price for the same amount of
computing power drops all the time. The situation is further complicated by the rapid spread
of networks, which link computers, and enable microcomputers to be used as terminals linked
to mainframes. Nevertheless, one can roughly say that, moving down these categories, the
computers progressively become cheaper, smaller, easier to use, needful of a less specialised
environment (such as air-conditioning) but also less powerful.
6. SOFTWARE
Computers are directed to perform each operation by a set of instructions, which define the
operation to be performed, and the data or device needed to carry it out. The various types of
sequence of instructions, which are actually put into the computer to perform a given task are
collectively known as software (program)
Software is intangible: we can only see the hardware on which it is carried. To use an
analogy, our brain (a physical organ of the body) represents hardware but our ideas (which
can be communicated but never seen or touched) represent software.
It is worth reinforcing the point that hardware is nothing without software. All the
supposedly 'hardware' items detailed in the section above require software to make them
work. Some are highly software-intensive, such as speech synthesis in which the hardware
elements are relatively simple. In the early years of computing, software took a back seat to
hardware. Now software is recognised as being a more important component of IT than
hardware as, for example, the global prominence of US company Microsoft attests.
There are three broad types of software, each of which is discussed below:
• System Software: which controls the basic internal operations of the computer system.
• System Development Software: the programming languages that are used to build other
software.
• Application Software: which does useful work by carrying out a particular task or
application. This can be divided into:
-General purpose application software (often called office automation (OA)
applications) which can be used in any part of an organisation.
-Application-specific software, which is used by specific organisational users for
specific purposes.
System Software
i. System Software in Common Use
• Operating System (OS) Software: controls the basic operations of the computer. This
includes:
- managing the interface between computer and user (that is the connecting link between
the computer and the human);
- controlling input, output and storage; and
- managing files in the memory and on disk.
- error reporting: detect and report any system or command errors
We can therefore think of the operating system as sitting between the human user and the
computer hardware, as indicated in Figure 4.
Figure 3: Role of the Operating System
Human User
Computer Hardware Operating System
When application software is being used on the computer, the operating system assists it. In
these cases, we can think of the OS as sitting between the application software and the
computer hardware, as indicated in Figure 5.
Figure 4: Role of the Operating System with Application Software
Human User
Computer Hardware Operating System Application Software
ii. Other System Software Technologies
• Utility Programs: perform specialist system management tasks such as detecting and
removing computer viruses, reporting on the performance of the computer system, or
scanning a disk for damaged or unused areas.
• Communications System Software: controls the sharing of resources and communication of
data between computers on a network. The main component is the network operating
system (NOS). Some ordinary operating systems now have a NOS embedded within them.
iii. Other Relevant Definitions
• Single user operating system software: allow only one user to utilize the resources of a
single-user computer system. A typical example is DOS (Disk Operating System).
• Multitasking: the ability of operating systems to run more than one task at the same time.
For example, they allow you to enter data into a database at the same time as printing a
document from your word processing package. This makes it easy to move data from one
application to another, e.g. to take a graph created by your spreadsheet and put it into a
report document being created by your word processor.
• User-friendliness: a measure of how easy any software program is to learn and to use
• Graphical User Interface (GUI): traditionally, operating systems were used by typing in
commands from the keyboard. Modern operating systems provide a GUI that is operated
using a mouse. GUIs are sometimes referred to as WIMP interfaces because they consist of
Windows, Icons, Menus and Pointers. The significance of this technology in the adoption
of new information systems can often be lost, but GUIs have spearheaded use of IT in
many areas because they reduce the skill and time barriers so significantly.
• Other Interface Modes: GUIs involve two interface modes – menus, and manipulation of
on-screen objects such as icons – which are both easy to learn and use, but relatively slow
and inflexible. They are therefore particularly useful for new users. Other interface modes
that may be used in systems (and other) software include:
-Question prompts: a question presented by the computer to which the user provides the
answer. For example, the question 'Save Changes Before Quitting? Yes/No'. These
help to guide users and are quick and easy to learn and use, but they are inflexible.
-Forms/dialogue boxes: a preset layout on screen with blanks that are filled in. For
example, a box requesting the name of a file to be saved. These are fairly quick and
easy to learn and use. They are inflexible, but deliberately so since they help guide the
users through certain processes more than any other mode.
-Direct commands: control of the system by directly typing in a command. For example,
pressing the keys 'Ctrl' and 'S' simultaneously to save a file. These take time to learn
and can be forgotten. However, they are the quickest mode to use and can be very
flexible, so experienced users like them.
Natural
language: a command typed in that is close to human conversation. For
example, 'List all files saved last Tuesday'. This takes little time to learn, is easy to use
and quite flexible. It can be particularly powerful for new users.
iv. System Software Trends
System software is becoming increasingly easy to use. For example, studies have shown that
it takes less than half as long to learn to use a GUI operating system compared with a text-
based OS. There has been an emergence of dominant standards: of one or two operating
systems that are found on the vast majority of computers. Finally, there has been the (slow)
emergence of non-English system interfaces.
System Development Software
i. System Development Software in Common Use
These are the programming languages that allow you to create the instructions that make up a
computer program. There are five main types, or generations, of programming language,
summarised in Table 4.
Table 3: Programming Language Generations
Name Widely Used
From
Example
Languages
Example of Language
Instruction
Machine language
(1st generation)
1940s Micro-code 5A 202
Assembler language
(2nd)
1950s ASSEMBLY,
PLAN,
AUTOCODOR
ADD B
High-level language
(3rd)
1960s COBOL, BASIC,
FORTRAN, C
INPUT "ENTER
CUSTOMER NAME";
NAME$
Fourth-generation
language (4th)
1980s FOCUS, Natural,
Power builder,
Access
LIST BY CUSTOMER
AVERAGE (INVOICE
TOTAL)
FifthGeneration1990sPROLOG
ii. Other System Development Software
• Web Authoring Tools: software development tools that help produce documents for the
World Wide Web.
• Computer-Aided Software Engineering (CASE): a software environment that aims to
automate as much as possible of the process of software development, from initial analysis
of problems through to creation of the final software program.
iii. Other Relevant Definitions
• Object-Oriented Programming Languages: software development tools that allow easy
manipulation of combined data/process items called 'objects'. This aims to make it easier
to write and re-write software by storing 'libraries' of reusable, generic objects. Examples
are C++, Java
• Visual Programming Languages: languages that allow the development of software
through use of a GUI rather than by just typing in programming instructions.
• Approaches to software development: in all there are four different ways in which software
is developed or obtained:
-Software package: buying a ready-made program 'off-the-shelf'.
-Customisation: modifying an existing software package to suit a particular user's needs.
-Custom-built: creating an entirely new piece of software from scratch.
-Re-engineering: modifying an existing custom-built piece of software.
iv. System Development Software Trends
With system development software, there is an increasing ability to rely on statements of what
is to be done, leaving the issue of 'how it is to be done' to the language. This can already be
seen in the changing instructions listed above in Table 4, and is referred to as the change from
procedural to non-procedural languages. This is allowing increasing end-user development
of systems with a change from complex and unnatural to easy and natural programming
languages or systems.
The time and effort required for system development is also decreasing because the process of
development is becoming increasingly automated, and because there is an increasing ability to
reuse software that has already been written. The overall amount of system development
within public sector organisations is decreasing because of the commoditisation of software,
that is, the increasing use of packages rather than custom-built software.
Finally, there is increasing hardware independence. Whereas machine language and
assembler are specific to one particular processor, the higher generation languages can be
used across a whole variety of computers.
General Purpose Application Software
i. General Application Software in Common Use
• Word Processing Software: supports the creation, storage and manipulation of documents
on the computer, including text and images. The single most widely used application of
computers.
• Database Management Software: supports the storage, organisation and selective retrieval
of data. Database management systems (DBMS) are often supplied with a fourth-
generation programming language (such as SQL: Structured Query Language) that assists
with the production of reports or retrieval queries.
• Spreadsheet: supports the manipulation of numerical data, including calculation, analysis
and graphical output. Spreadsheets are based on an on-screen matrix of 'cells' into which
numerical (or other) data can be typed. They are used particularly for financial and
statistical work.
• Electronic Mail (email) Software: transmits and receives messages or files between one
computer to another. Email requires the computer to be connected to a network.
• Web Browsing Software: used for accessing documents and other products and services on
the Web and the Internet
ii. Other General Purpose Application Software
• Desktop Publishing (DTP) Software: a more powerful and sophisticated version of word
processing software. It has recently been somewhat compromised by the increasing power
of word processing programs.
• Graphics Software: allows the create and manipulation of graphics and drawings. Like
DTP, this has been squeezed by the increasing graphical capabilities of word processing
and spreadsheet programs. One continuing use is presentation graphics software that can
produce slides or overhead projections.
• Statistical Packages: Statistical packages are software for data analysis and report writing
purposes. Features include: interactive facilities for storage and retrieval of data from
various sources, data entry and modification services, elementary and advanced statistics,
report writing, graphics, and online tutorial and help facilities. Examples include: SAS,
SPSS, Micro Stat, PSTAT, MiniTab, Statistica.
• Project Management Software: supports the planning, monitoring and control of projects.
iii. General Purpose Application Software Trends
This software is becoming increasingly easy to use, especially following the introduction of
GUIs. It has increasing functionality (i.e. the ability to do more and more things on the
computer), and there is increasing integration, particularly of communications software with
other software applications. The cost of packages is static or decreasing in real terms. As in
other IT areas, there has been the emergence of dominant standards: of one or two packages
in each category that are found on the vast majority of computers.
Application-Specific Software
i. Application-Specific Software in Common Use
• Basic Data System (BDS): captures, processes and stores the data that is fundamental to
the formal operation of the organisation. The most common form is the transaction
processing system (TPS) which records the day-to-day, repetitive operational transactions
of the organisation, such as those involving the payment or receipt of money.
• Management Information System (MIS): provides reports that assist with the managerial
monitoring and control of organisational functions, resources or other responsibilities. For
example, software to assist monitoring of expenditure from departmental budgets.
• Decision Support System (DSS): provides analytical modelling capabilities to assist with
managerial planning and the making of decisions in ill-structured situations. For example,
software to assist the financial appraisal of potential new projects.
ii. Other Application-Specific Software
• Executive Information System (EIS): provides the information and other functions
necessary for strategic decision making. For example, software to assist long-term human
and financial resource planning.
• Group Decision Support System (GDSS): provides data-gathering, analysis and reporting
functions to help a group of people make a decision in an ill-structured situation. For
example, software to assist negotiations between management and unions.
• Expert System (ES): encodes human expertise as facts, relationships and rules and applies
these to problem solving. For example, software to advise which type of social security
payment, if any, an applicant is eligible for. Expert systems are part of a wider group of
decision-prescribing systems that take decisions themselves or suggest the optimum
decision to users. Expert systems are also part of a wider body of computer applications
called artificial intelligence (AI). As its name suggests, AI seeks to recreate the process of
the human mind using machines and it also includes natural language processing, speech
recognition and synthesis, machine translation, computer vision, and robotics.
• Specialist Support Systems: these assist the work of particular professional specialists. For
example, professional designers may use computer-aided design (CAD) packages.
• Geographic Information System (GIS): stores and manipulates data relating to places on
the earth's surface. For example, a system that maps the existence and exploitation of
natural resources in a country.
• Functional Information System: combines the functions of more than one information
system to support the specific activities of one functional organisational area at different
management levels. For example, an accounting information system might combine a
transaction processing system to capture accounting data with a management information
system and a decision support system to provide support to different types of management
accounting decision. Most MIS and DSS receive their data from a TPS or other basic data
system. Indeed, some MIS and DSS are created just by adding a different interface onto an
existing basic data system.
• Cross-Functional Information System: integrates various different functional information
systems. For instance, information systems covering the main functions of the
organisation can be linked up with each other and with external information. They may
then form the main inputs to an executive information system, which is a type of cross-
functional information system.
• Inter-organizational information systems (IOS): these are systems that are used to facilitate
business transaction and information interchange among different organizations. An earlier
example is Electronic Data Interchange (EDI) but most recent eCommerce and eBusiness
systems have this feature
iii. Application-Specific Software Trends:
These software has an increasing capacity to support and/or automate human capabilities.
They have seen an increasing addition of user-friendly interfaces, and of communications
capabilities. Another trend is the shift from silos of function and organization specific
information systems to integrated information systems that integrate not only different units
of an organization but also an organization’s partners.
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