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MOTHER TERESA INSTITUTE OF SCIENCE AND TECHNOLOGY
SATHUPALLY-507303
KHAMMAM(DT)
Presented By:
M.MANOHAR
IIIrd CSE
[07C61A0559]
[email protected]
M.SARITHA
IIIrd CSE
[07C61A0560]
[email protected]
Agenda
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Abstract
Introduction
A Simple Operating System
Difference Between Simple Operating System and Real Time
Embedded Operating System
Task Swapping Methods
Task Synchronization
Using Mutexes
Using semaphores
Disaster management system using microcontroller 89c51
Limitations of Real Time Embedded System
Market Survey For Real Time Embedded Systems
Development environment and Facilities
Conclusion
Abstract
 RTO’S i.e. real time operating systems is a class of
operating systems intended for real time application.
The main characteristic of a real time embedded
operating system is its defined response time to
external stimuli
 The presentation explains the working of a simple
operating system and then shows the differentiation
between the simple and operating system and a real
time operating system
Interrupt
Introduction
Controller
Command
Limit Switch
 Real time operating systems is a
Maximum
Response Time.
Belt Drive
class of operating systems intended
for real time application.The main characteristic of a real
time embedded operating system is its defined response
time to external stimuli. For example if a peripheral
generates an interrupt, a real time operating system will
acknowledge and start to service it within a maximum
defined time.
A Simple Operating System
USER
TASKS
SESSION MANGEMENT
FILE-MANGEMENT
PHYSICAL I/O
REAL TIME
HARD
WARE
KERNEL
LOGICAL I/O
Difference Between Simple Operating System and Real
Time Embedded Operating System
 A real time system is very small in size whereas the
desktop operating system is huge.
 A real time system is very small in size whereas the
desktop operating system is huge. Even 8-16 MB
memory is considered to be luxury for RTO whereas
for a desktop system 300 – 500 MB space is less. RTO’S
are not acquired with facilities of huge libraries,
management plug and play features whereas desktop
operating systems.
Task Swapping Methods
 Time slice

Time slice can be used where time critical operations are not
essential.
 Pre-emption
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The alterna
tive to time slicing is to use pre-emption where a currently
running task can be stopped and switched out - pre empted –
by a higher priority active task.
 Co – operative multitasking

This is a mechanism behind Windows 3.1 and while not in use
to real time application for reasons which will become
apparent it has been included for reference.
Task Synchronization
 The tasks in RTO’s need to interact with each other i.e.
they must be synchronized and communicate with
each other.
 This can be very much illustrated by a simpler example
 Suppose that two roads are running parallel.
 Hence there is no communication between the cars as
they do not meet each other and run parallel.
Using Mutexes
 In the discussion above we summarized that the
situation in following points
1)Problem occurs only when a resource is shared among
task.
2) Synchronization needs to be done only during resource
acquisition and release.
Using semaphores
 A semaphore is another mechanism similar to that of
mutexes which can be used to achieve synchronization
of task and resources.
 For example, suppose that there is a single platform
and there are too many trains who want to acquire the
platform at the same time.
P1
P2
P3
P4
Disaster management system
using microcontroller 89c51
 Well this is a project which can be very much useful to
people in the poor villages of India. This system
enables wireless communication between a village and
a city in India or else in any other country.
 Suppose if a disaster tends to happen in a village only
with the use of a switch the disaster management
people in the city can come to know that a disaster like
a drought, flood, earthquake etc.
Limitations of Real Time
Embedded System
 Limited operating systems support for programming.
 Limited secondary memory.
 Limited random access memory.
 Limited processing power.
 Interaction with hardware.
 Absence of standard input/output devices.
Market Survey For Real Time
Embedded Systems
 Hardware

A potential customer for a Real time embedded system is rarely in
the position to choose the hardware (i.e. target processor) on which
these systems will run on. Therefore, Real time embedded systems
availability.
 Design

These systems can be designed as a monolithic (one piece of
software with many interacting modules), layered or client-server
structure.
 Standards

A Real time system needs to interact with application components
and its environment through well-defined interfaces.
Development environment and
Facilities
 1) Tasking model.
 2) Inter-process communication mechanism.
 3) Memory protection.
 4) Scheduling policy
Conclusion
 Thus, a real time embedded system is an enabling
technology that will be a part of both micro and macro
systems.
 So by developing up such a system it will be a great
boon to mankind and may help in changing people’s
fortune from day to day by making their work more
easy and efficient and in some hazardous
circumstances even help in saving peoples life.
Questions?