Computer
Systems
Nat 4/5 Computing Science
Operating Systems
Lesson Aims
 By
the end of this lesson:
 All pupils will be able to:



Describe what an operating system is
Describe what an application program is
Describe the functions of an operating system
Nat 4/5
Types of software
 There
are two main types of software:
 Applications

These are pieces of software that perform a
particular task such as word processing or
desktop publishing
 Systems

Software (Operating Systems)
These types of software control the running of
hardware and the running of other software
Nat 4/5
Applications Software
 Application
software are programs that are
designed to do a particular task.
 For example the Word Processor your
revision notes were written in is an
application program.
Even games are
application programs.
Nat 4/5
Operating Systems
 An
operating system is a piece of software
that controls the operation of the systems
hardware and the running of other
software.

Two of the more popular operating systems
used at present are
 Microsoft®
Windows
 Apple® OSX.
Nat 4/5
Why is it important?
 You


Which operating system do you write it for?
IOS® Android ® Windows ® ?
 Why
 If
are writing an app for a smartphone
do you need to bear this in mind?
I buy Office 2010 for windows – can I install
it on a Mac?
Nat 4/5
Operating Systems: Functions

All operating systems have certain common functions:
Provision of an Interface
• This is the means of interacting with the user. Most modern
operating systems provide a GUI (Graphical User Interface)
Input Output
• Controls the sending and receiving of data to and from
peripherals
Memory Management
•Controls the systems RAM, controlling which locations in RAM
programs are loaded into
File Management
• Controls where and how files are saved onto backing
storage.
Error Reporting
• Providing useful feedback to users when errors do occur.
Emulators
 An
emulator is a
utlility program
which allows a
computer to run a
different operating
system.
 This gets round the
problem of not
being able to run
software because
it has been written
for a different
operating system.
 An
example is
“Parallels Desktop”
which allows an
Apple computer to
run Windows
software
Nat 4/5
Summary


The Operating System (OS) of a computer is a
program which manages the hardware and
the running of other software on a computer
system.
The standard functions of an OS are:





Provision of a human/computer interface
Input/Output
File Management (backing Storage)
Memory management (RAM)
Error Reporting
Nat 4/5
Summary (2)


An application program is a piece of
software that performs a particular task
such as games, word processers.
An emulator is a utlility program which
allows a computer to run a different
operating system.