Distributed systems allow autonomous computers to communicate and cooperate over various communication lines. A distributed operating system provides transparency and facilitates sharing and access of remote resources. Real-time systems must process within defined time constraints or fail. They prioritize quick event response over user convenience. Real-time operating systems rely on policies like meeting scheduling deadlines.

1. Basics of Operating Systems
: Distributed and Real systems
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2. Basics of Operating Systems
: Distributed and Real systems
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3. Recap
In the last class, you have learnt about
• Multiprogramming
• Time Sharing
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4. Objectives
On completion of this period, you would be able to know
• Distributed Systems
• Real Time Systems
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5. Distributed Systems
• Distributed systems are loosely coupled systems
• A Distributed computer system is a collection of
autonomous computer systems
• Distributed systems communicate with one another
through various communication lines like high speed buses
or telephone lines
• The processors in a distributed system may vary in size
and function
– Example: small microprocessors, workstations , minicomputer and
large general purpose computers 5

6. Distributed Systems (contd..)

7. Distributed System
• Processors in distributed systems are referred by no. of
different names like, sites, nodes, computers, etc.
• Important reasons for building distributed systems are
– Resource sharing
– Computation speedup
– Reliability
– Communication
• The key objective of a distributed operating system is
transparency
• Ideally, component and resource distribution should be
hidden from users and applications programs unless they
explicitly demand
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8. Distributed System
• A distributed operating system governs the operations of a
distributed computer systems and provides a virtual
machine abstraction to its users
• Distributed operating system usually provides the means
for system-wide sharing of resources, such as
computational capacity, files and I/O devices
• Distributed operating system facilitates access to remote
resources, communication with remote process and
distribution of computation
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9. Real-Time System
• Real-time systems has well defined, fixed time constraints
• Processing must be done with in the defined constraints, or
the system will fail
• For example:
• It would not do for a robot arm to be instructed to halt after it had
smashed into the car it was building
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10. Real-Time System

11. Real-Time System
• Real-time system is used as a control device in a dedicated
application
• Sensors bring data to computers
• Computer analyze data and adjust controls to modify the
sensor inputs
• Example:
• Scientific experiments, medical imaging systems, industrial
control systems etc..
• Real-time system functions correctly only if it returns the
correct result within its time constraints
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12. Real-Time System
• A primary objective of real-time systems is to provide
quick event - response times, thus meet the scheduling
dead lines
• User convenience and resource utilization are of
secondary concern to real- time system designers
• Real-time operating systems usually rely on some
specific policies and techniques for doing their job
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13. Real-Time System
• Memory management in real-time systems is
comparatively less demanding then in other types of
multiprogramming systems
• The primary reason for this is that many process
permanently reside in memory in order to provide quick
response time
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14. Real-Time System
• File management is usually found only in larger installation
of real-time systems
• In fact, some embedded real-time systems, such as an
onboard automotive controller, may not even have any
secondary storage
• These include protection and access control
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15. Summary
• A primary objective of real-time systems is to provide
quick event - response times, and thus meet the
scheduling dead lines
• User convenience and resource utilization are of
secondary concern to real- time system designers
• A distributed computer system is a collection of
autonomous computer systems capable of
communication and cooperation via their hardware and
software interconnections
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16. Frequently Asked Questions
1. Explain about Real Time Operating System
2. Explain about Distributed Operating System
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17. Quiz
1. File management is usually found only in larger
installation of real-time systems
Yes
No
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18. Quiz
2. A distributed computer system is a collection of
autonomous computer systems capable of
communication and cooperation via their hardware and
software interconnections
Yes
No
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19. Other subject materials
• Web designing
• Micro processors
• C++ tutorials
• java
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