An operating system (OS) acts as an intermediary between users and computer hardware, managing resources and providing user interfaces. It is essential for executing user programs efficiently, and its functionalities vary across devices from personal computers to mobile devices and embedded systems. The OS is a critical component of computing systems, facilitating usability and efficient resource management.

1. Operating System 02
OS as an Extended Machine
Prof Neeraj Bhargava
Vaibhav Khanna
Department of Computer Science
School of Engineering and Systems Sciences
Maharshi Dayanand Saraswati University Ajmer

2. What is an Operating System?
• A program that acts as an intermediary
between a user of a computer and the
computer hardware
• Operating system goals:
– Execute user programs and make solving user
problems easier
– Make the computer system convenient to use
– Use the computer hardware in an efficient
manner

3. Operating Systems
• All devices have an operating system
• Software which manages the hardware
• Creates the interface between the
hardware and the user
• Functions performed by the
operating systems:
– Managing the hardware resources of the
computer
– Providing the user-interface components
– Providing a platform for software developers
to write applications
• Most popular are Microsoft Windows,
Apple Mac OS, and Linux

4. What Operating Systems Do
• Depends on the point of view
• Users want convenience, ease of use and good
performance
– Don’t care about resource utilization
• But shared computer such as mainframe or
minicomputer must keep all users happy
– Operating system is a resource allocator and control
program making efficient use of HW and managing
execution of user programs
• Users of dedicate systems such as workstations have
dedicated resources but frequently use shared
resources from servers

5. What Operating Systems Do
• Mobile devices like smartphones and tables
are resource poor, optimized for usability
and battery life
– Mobile user interfaces such as touch screens,
voice recognition
• Some computers have little or no user
interface, such as embedded computers in
devices and automobiles
– Run primarily without user intervention

6. Defining Operating Systems
• Term OS covers many roles
– Because of myriad designs and uses of OSes
– Present in toasters through ships, spacecraft,
game machines, TVs and industrial control
systems
– Born when fixed use computers for military
became more general purpose and needed
resource management and program control

7. Operating System Definition (Cont.)
• No universally accepted definition
• “Everything a vendor ships when you order an operating system” is a good
approximation ….. But this varies wildly
• “The one program running at all times on the computer” is the kernel, part
of the operating system
• Everything else is either
– a system program (ships with the operating system, but not part of the
kernel) , or
– an application program, all programs not associated with the operating
system
• Today’s OSes for general purpose and mobile computing also include
middleware – a set of software frameworks that provide addition services
to application developers such as databases, multimedia, graphics

8. OS as an Extended Machine
• An operating system is the most important program in a computer
system. This is one program that runs all the time, as long as the
computer is operational and exits only when the computer is shut
down.
• The fundamental goal of computer systems is to execute user
programs and to make solving user problems easier. Hardware of a
computer is equipped with extremely capable resources – memory,
CPU, I/O devices etc.
• All these hardware units interact with each other in a well-defined
manner. Also various programs require certain common operations,
such as those controlling the I/O devices.
• The common functions of controlling and allocating resources are
then brought together into one piece of software: the operating
system.

9. Goal of OS
• Operating systems exist because they are
supposed to make it easier to compute with them
than without them.
• Efficient operation of the computer system is a
secondary goal of an operating system. This goal
is particularly important for large, shared multi-
user systems.
• Operating systems are the programs that make
computers operational, hence the name
Operating (the )system.

10. Operating System as an Extended
Machine

11. Assignment
• 2. Define Operating System and discuss the role of Operating
System as an Extended Machine.