A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time applications that process data as it comes in, typically without buffer delays. Processing time requirements (including any OS delay) are measured in tenths of seconds or shorter increments of time.

1. Real time Operating System
Start with the Name of Allah , Who is Most Merciful & Beneficial
Lecturer: Engr Shamillah Nasreen
Group Member:
KhuramShahzad
Malik Adnanul Haq

2. INTRODUCTION
A Real time Operating System:
• Must have well defined, fixed time Constraints, Otherwise
System will fail.
– Which is specially designed for Embedded System.
– RTOS is also called Brain of Real time system.
e.g. Medical Imagining System, Weapon System.
Real time Operating System

3. What is Real time?
• The ability of the
operating system to provide a required level of service in a
bounded response time.
– Example:
Airbag has to be opened within a fixed time immediately
after the crashing in order to protect from any injuries.
Real time Operating System

4. Types of RTOS?
• Hard real time Operating System
• Soft real time Operating System
❖ Hard real time:
Guarantees that tasks must be completed:-
– within the specified timeframe,
– But they must also be completed correctly.
– e.g. air traffic control , vehicle subsystems control, medical systems.
• Nuclear power plant control

5. Types of RTOS?
❖ Soft real time: Meets the deadline usually.
Critical Tasks are completed:
– as fast as possible without having to be completed within a
specified timeframe.
– Provides priority of real-time tasks over non real-time tasks.
– Also known as “best effort” systems.
– Example – multimedia streaming, computer games
Real time Operating System

6. Graphical Representation

7. Difference Between RTOS & GPOS
• The basic difference of using a GPOS
or
an RTOS lies in the nature of the
system
i.e whether the system is “time
critical”
or not.
• Normal operations that we do in a
computer are not time critical & nothing
is going to happen if it takes a few more
seconds to open a file.
e.g. Missiles, ABS is cars, timing is very
critical.

8. Advantages RTOS
• Maximum consumption
• Task shifting
• Focus on application
• Used in embedded system
• Error free
• 24-7 system
• Memory allocation
Real time Operating System

9. Disadvantages RTOS
• Use heavy system recourses
• Low multitasking
• Complex algorithm
• Device driver and interrupt signals
• Thread priority
Real time Operating System

10. FUNCTION OF RTOS?
• Task management
• Scheduling
• Resource Allocation
• Interrupt Handling
Real time Operating System

11. Task Management in RTOS
• In Real Time Applications, any Process which takes a specified
execution time
and occupies predefined amount of memory is called as a Task.
• Task management is the process of managing tasks through its life
cycle
❖ Typical Task Operation
– Creating and deleting tasks,
– Controlling task scheduling, and
– Obtaining task information.
Real time Operating System

12. Task Management in RTOS
Task Management Life Cycle

13. Scheduling in RTOS
• Task management provides the following
information about tasks:
– No of tasks
– Resource Requirements
– Release Time
– Execution time
RTOS Scheduler uses scheduling
algorithms to organize them.
• Algorithm
– Round Robby, Priority Scheduling etc.
Real time Operating System

14. Resource Allocation
• We Know that RTOS(Embedded System):-
– have Limited amount of Resource in terms of memory & CPU
power.
• It is essential to allocate the available
resources efficiently
• The same algorithms used for scheduling
are again used for resource allocation.
– Round Robby, Priority Scheduling etc.
Real time Operating System

15. Interrupt Handling
• Interrupt is any external control signal
which disturbs the normal execution of a
system.
• Interrupts cause
– The processor to suspend all other operations whatever it is
doing & instead execute the code
–

16. INTER-TASK COMMUNICATION
INCLUDES:
a. Shared Memory: For simple sharing of data.
b. Signals: For exception handling.
c. Message Queues and Pipes: For inter-task message passing.
d. Sockets and RPC: For network transparent inter-task
communication.
e. Semaphores: For basic mutual exclusion and synchronization.
Real time Operating System

17. Popular RTOS
• VxWorks
• LynxOS
• RTLinux
• Windows CE
• These are some of the popular RTOS
used in the industry.
• VxWorks is the most widely used RTOS.
Real time Operating System

18. Vx Works
• VxWorks is a real-time operating system (RTOS)
• The popular RTOS used in the industry.
• VxWorks is used to control network and communication
devices, test and measurement equipment, computer
peripherals, automotive systems.

19. APPLICATIONS FOR RTOS:
• Navigation systems
• Deep sea instrumentation
• Traffic control system
• Radio and optical telescope
• Radar systems
• Network switching control systems
• Satellite monitoring systems
• track-and-trace spy satellites
• Robotics
Real time Operating System