Operating Systems &
Computer Architecture
CT049-3-1-OS&CA
Ver: VE
Introduction to Computer
Architecture
Topics we will cover
• The System Concept
• Physical Systems
• Conceptual Systems
• IT System Architecture
• Distributed System Processing
• Example: Google
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Learning Outcomes
At the end of this section, YOU should be able to:
•
•
•
Understand the basics of architecture
Understand the basic architecture of a computer and an IT system
Understand the components of systems and how they are studied
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Key Terms
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What is a System?
A System is a group of inter-related components working together to produce an
outcome. A System may consist of physical or conceptual components.
•What do the following systems have in common?
1.
2.
3.
4.
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Plumbing system
Solar system
Home network system
Inventory control system
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Plumbing System
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Solar System
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Map
The Egyptians mapped out the components of this system to understand
cosmic events.
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Map
It is through the study of
Systems and their architecture
that we gain better insight and
understanding.
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Language (System as a Concept)
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Lunar Calendar (System as a Concept)
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Home Network System
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Inventory Control System
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Definition of a System
• “ A systems is a collection of components linked together and
organized in such a way as to be recognizable as a single unit.”
• Linked components of a system also define the boundary for the
system
• The environment is anything outside of the system
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Representation of a System
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Representation of a System E.g.
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System Decomposition
• Components
– May be irreducible or
– May be subsystems
• Decomposition
– The division of a system into its components and linkages
– Hierarchical
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System Architecture
“The fundamental properties, and the patterns of relationships,
connections, constraints, and linkages among the components and
between the system and its environment are known collectively as
the architecture of the system”
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Abstraction of Systems
• Abstraction: Information hiding
• The process of taking away or removing characteristics from
something in order to reduce it to a set of essential characteristics.
• In order to fully understand how Systems work, we must break them
down into simpler units… hence Abstraction.
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Organization Chart
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Business Application Architecture
How are the previous two
abstractions of a business
system
different
from
one
another? (Organization Chart VS
Business
Application
Architecture)
How are these abstractions
different from the real business
system?
(Organization Chart VS Business
Application Architecture)
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IT System Architectures
• Distributed processing systems
– Client-Server Computing
•
•
•
•
2-tier architecture
3-tier architecture
N-tier architecture
Web-Based Computing
– Peer-to-Peer Computing
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Client Server Computing
• A program on a client computer requests services from a program on
a server computer
• Examples:
– Email services, file services, print services, directory services, Web services,
database services, application services, remote access services
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Basic Client-Server Architecture
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Advantages of Client-Server Architecture
• Centralization of services permits
–
–
–
–
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easier administration of services by IT professionals
easier availability and location by users
consistency of resources, such as files and data, can be managed and assured
more efficient and cost-effective hardware procurement through purchasing a small
number of very powerful computers
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Clients and Servers
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Multi-tier Architectures
• Two-tier architecture
– Two computers are involved in a service.
– Example: Web-browser and Web server
model used in intranets and on the Internet
• Three-tier architecture
– Three computers are involved in a service
– Example: client computer, Web server,
database server
• N-tier architecture
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Three-tier Architecture
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Peer-to-Peer Computing
• Computers on a network are treated as equals
• Each computer can share resources with the other
computers on the network
• Disadvantages
– Difficult to establish centralized control of services
– Difficult to locate services
– Difficult to synchronize versions of files or software
– Difficult to secure network from unauthorized access and from
viruses
• Advantages
– Sharing files between personal computers
– Internet file sharing
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Hybrid Model of Computing
• Client-server technology used to locate systems and files
• Then systems can participate in peer-to-peer transactions
• Examples
– Instant messaging
– Skype
– Napster
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Google’s System Architecture
• Provide powerful, fast search capability for material on
the Internet
• Derive income from advertising that is targeted to
each user based on their searches
• Basic requirements
– Capable of responding to millions of simultaneous requests
from all over the world
– Perform a web crawl of the Internet retrieve and organize data
– Establish ranking of results with appropriately targeted
advertising
– High reliability of the system
– System is easily scalable and cost effective
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Google’s Data Center Architecture(Search)
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Google’s Hardware Architecture
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Ethics
“With great power comes great responsibility”
Ethics.: The Moral principles which govern a person’s or group’s behavior.
Understanding the Architecture of Systems brings about many
benefits, however if used in-appropriately will also cause harm.
History has shown how the careless use of knowledge and power
has brought about disservice to the human race.
So, a Fundamental question must be asked, is Computer Technology
in all it’s various applications beneficial or detrimental to humanity?
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Quick Review Questions
•
What are the most important ideas, keywords, and phrases that are stated in the definition of a system?
•
Explain the relationships among the following words: system, environment, boundary, interface.
•
Explain the following statement about systems: ‘‘Decomposition is inherently hierarchical.’’
•
Explain what is meant by the architecture of a system.
•
The human body is an example of an object that can be represented as a system. Consider the various
ways in which you could represent the human body as a system. Select a representation and identify the
components that constitute the system. Select one component and decompose it to the next subsystem
level. Now consider a completely different system representation of the human body and repeat this
exercise.
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Summary
When working with large concepts with defined boundaries, it is often easiest to think of them in terms of
systems. A system can be defined as a collection of components, linked together and organized in such a
way as to be recognizable as a single unit. The components themselves may also be recognized as
subsystems, to be further reduced into components, when appropriate. The area outside the boundaries of a
system is its environment.
The system affects and is affected by various elements of the environment. In many situations, the
environment supplies inputs to the system and receives outputs from the system. The patterns of
relationships, connections, constraints, and linkages among the components of a system and between a
system and its environment are known collectively as the architecture of the system. Information technology
systems are systems that support the strategy and operations of organizations.
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END
Q&A
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Next
Data Representation
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