Software, O/S & Interfaces
F451 - AS Computing
Hardware and Software
• Definition Hardware
– The physical components
that make up a computer
system. Includes all
input, output, storage
devices
• Definition Software
– The computer programs
that tell the computer
what to do.
Layers of software
• Application Software
– General purpose
– Special purpose
– Bespoke
• System software
– Operating system
software
– Utility programs
– Library programs
– Compilers, assemblers
and interpreters
Library
programs
Systems & Application Software
• Systems Software controls the operation
of the hardware/runs the
computer/manages the applications
• Applications Software makes the
computer do something useful carries out
tasks
Applications Software
• The term applications software refers to
all the programs used for a wide variety of
purposes
• There are three categories:
– general purpose
– special purpose
– bespoke (custom).
General purpose software
• The term general purpose software refers to
applications with a number of common uses:
– word processing packages
– spreadsheet packages
– database packages
– presentation packages
Special purpose software
• Special purpose software is designed to
carry out a specific task
• It is commonly used by organisations,
businesses
–Stock control
–Payroll systems
–Accounting
Bespoke (custom) software
• The term bespoke software refers to
software that is tailor-made rather than
bought off-the-shelf.
• It may be created in-house or using
programmers from a software house.
System Software
• The term system software refers to the
software that is needed to set up and run
the computer.
• This software is often invisible to the user.
• There are four types of system software:
– operating system software
– utility programs
– library programs
– compilers, assemblers and interpreters.
Operating System Software
• The operating system software (OS) is a
suite of programs that controls the
hardware and software.
• It acts as an interface between the user
and the computer.
Role of Operating Systems
• Used to control the hardware of the system and
resource management through software like
hardware drivers/system software
• Used to provide a platform on which applications
can run
• Deals with issues that the software may have
with eg storage of files
• Provides a user interface
• Allows communication between user & hardware
• Has many utility programs used to carry out
housekeeping on system
Utility Programs
• Utility programs are software written to
carry out housekeeping tasks on the
computer.
• Examples include:
– spell-checkers
– wizards
– compression software
Compression Software
• Reduces size of files
• Useful when large files are being
sent via email
• The compression means they are
sent more quickly
• They are decompressed using a
decompression algorithm
File Handlers
• Manages data storage/organises
data storage
• Allows files to be accessed
• Allows for deletion/sorting of files
Hardware Drivers
• Contain the instructions to the OS for
using a peripheral e.g.. a printer
• Allows control of peripheral by OS
• Written in a low level language (assembly)
Backup Utility
• Automatically
makes copy of
files at regular
intervals
• Can be set to run
a full or
incremental
backup
Library Programs
• They are similar to utility programs,
although they are essential to the user.
• The library program may work alongside
many different applications.
• An example could be the science
department of a university whose users
may need mathematical library programs
to carry out tasks on scientific data.
Compilers, assemblers and interpreters
• Compilers, assemblers and interpreters.
• A program is a series of instructions.
• Compilers, assemblers and interpreters
are used to turn these instructions into
machine code that the computer can
carry out the instructions.
Different Methods of O/S
•
•
•
•
Batch Processing
Real Time Processing
Single User
Multi User
Batch Processing
• Commonly used in:
–Payrolls
–Banks
–Billings
–Financial Sector
Batch Processing
• Often run during night time/weekends
• No need for human to be present
• Run in computer downtime when workers
have gone home
• No need for instant response to inputs
• Processes large amounts of data in one go
Real Time Processing
• Data is processed instantly
• System responds instantly to changes
in input
• Automatic Pilots on Airplanes
– Computer controlled systems
User Interface
• The method where the user tells the
device what to do and the device
responds.
–Computer
–Mobile Phone
–ATM
–Car
Menu Driven Interface
• Easy to use
• Require little technical
knowledge
• Limited to the options
available
Graphical User
` Interface
Advantages
• Commonly used
• Easy to learn
• Intuitive
Disadvantages
• Require more processing power and
system resources
4 Features of a Graphical User
Interface
Windows
Icons
Menu
Pointers
Designing a User Interface
• Factors to consider include
– Use of sound
• Warnings to user
– Colours Used
• Easy on the eye
• Experience of User
– CLI can be difficult to master
• Platform
– GUI requires more processing power
Designing a User Interface
• Must consider environment when
designing an interface – e.g. an office
environment or a factory have different
level of noise, light.