Operating Systems Overview

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Operating Systems Overview

• Chapter 1

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Operating System Concept
Application Software
Operating System
Keyboard
Monitor
Hardware
CPU, Disk
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Computer System Layers
Application Software
Operating System
Users
User
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Windows 2000
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Windows 2000
Security Subsystem
Win 32 Apps
Win 32 Subsystem
Account Manager
Window Manager
Executive
Kernel
Graphic Device Drivers
Hardware Abstraction Layer
Hardware
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Hardware Abstraction Layer
Virtual Machine Interface
Hardware Abstraction Layer
Graphic Device Drivers
Portable over Intel CPUs
Hardware
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Kernel
Processes
Events
Mutants
Interrupts
Mutex
Power status
Threads
Kernel
Profile
Semaphores
HAL
Kernel runs at all times on the computer.
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Executive
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Executive
File systems, Cache management Device
Drivers Network Drivers
Creates, deletes uses threads and processes
Supervises use of all objects
Create, Open, Close, Delete, Query Name, Parse,
Security
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Executive
Recognize and adapt to changes in hardware
configuration
Run-time access validation
Virtual to physical mapping Paging Multiprocessor
Cache Coherence
Client process to OS service message passing
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Typical PC
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Latest PC
System Bus 533 MHz
P4
Cache
AGP Bus 8 Gbytes/sec
North Bridge
Video Card
Main Memory
South Bridge
Audio
PCI
133 MHz
IDE
USB 2.0
480 Mbps
Disks
RAID
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CPU Organization
Program Counter
OPCODE
Instruction Register
Program Status Word
Arithmetic Logic Unit
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Intel 80386 General Registers
Pointers
CS
Segment Registers
Accumulators
DS

Instruction Pointer
IP
EFLAGS
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What is an Operating System?

• Resource manager
• - manages and allocates resources (hardware -
  disk space, CPU time...)
• Program controller
• - controls the execution of user programs
• - controls operation of I/O devices

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What is an Operating System?

• An operating system is similar to a government
• It performs no useful function by itself
• It provides an environment within which other
  programs can do useful work

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Goals of Operating Systems

• User convenience
• - e.g. Graphic User Interfaces
• Efficiency of the computer
• - mainframe code execution
• - e.g. weather modelling and prediction

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Early Batch Systems
Mainframe

• Programs loaded in batches
• (multiple programs in memory)

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Early Batch Systems
Operating System
Operating System
User Program

• Multiprogramming batch with scheduling

• Simple batch

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Scheduling
Memory

• Job scheduling

• CPU scheduling

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Interactive System
Mainframe

• Dynamic interaction with users
• Needs short response times

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Time-Sharing System
Mainframe

• Dynamic allocation of resources

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Time-Sharing System

• Dynamic allocation of resources

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Time-Sharing System

• Dynamic allocation of resources

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Time-Sharing System

• Dynamic allocation of resources
• Virtual memory

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Desktop Systems

• Each user runs own operating system
• Low protection, independent use

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Networked Desktop Systems

• Each user runs own operating system
• More protection, shared resources

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Workstations
CPU 1
CPU 2
...
CPU n

• Multiprocessor Systems

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Multiprocessor Systems

• Increased throughput
• Economy of scale
• - share peripherals
• Increased reliability
• - graceful degradation, fault tolerant
• Parallel systems, tightly coupled systems

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Multiprocessor Systems

• Graceful Degradation
• the ability to continue providing service
  proportional to the level of surviving hardware
• Fault tolerant system
• systems designed for graceful degradation

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Multiprocessor Systems
CPU 3
CPU 1
CPU 2
Memory

• Symmetric Multiprocessing(SMP)

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Multiprocessor Systems
Master
CPU 3
CPU 1
CPU 2
Memory

• Asymmetric Multiprocessing

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Multiprocessor Systems

• Symmetric Multiprocessing
• each processor runs an identical copy of the
  operating system
• these copies communicate with one another as
  needed
• Asymmetric Processing
• each processor is assigned a specific task
• a master processor controls the system

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Networks

• Local Area Network
• exists within a room, a floor or a building
• Wide Area Network
• exists between buildings, cities or countries
• Metropolitan-area network
• links buildings in a city
• Small area network
• between equipment in a room

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Distributed Systems
PC 3
PC 1
PC 2
Network

• Local Area Network (LAN) in site
• Wide Area Network (WAN) between sites
• Loosely coupled systems

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Distributed Systems
PC 3
PC 1
PC 2
Network
Server

• Compute-server system
• File-server system

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Client-Server Systems

• Computer-server systems
• provide an interface to which clients can send
  requests to perform an action, then execute the
  action and send results to the client
• File-server systems
• provide a file-system interface where clients can
  create, update, read and delete files

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Peer to Peer Systems

• TCP/IP Peer to Peer Connection
• network between computers with equal status
• allows printer and internet access sharing

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Clustered Systems
PC 3
PC 1
PC 2
Server
LAN

• High availability

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Clustered Systems
PC 3
PC 1
PC 2

• Asymmetric Clustering

Hot standby
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Clustered Systems
PC 3
PC 1
PC 2

• Symmetric Clustering

Monitor one another
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Clustered Systems

• Parallel clusters
• (multiple hosts, shared data storage)
• Cluster software
• (Oracle Parallel Server)
• Storage Area Networks (SANs)
• Clustering over a WAN

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Real Time Systems

• Hard real-time
• Soft real-time

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Handheld Systems
Network

• Memory 512 kB - 8 MB
• Low power, slow processors

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Feature Migration
Mainframe Mini Desktop Handheld
MP
LAN
MP
LAN
MP
LAN
LAN
1950 1960 1970 1980 1990 2000 2010
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Future Trends

• Web-based computing
• Web portals, wireless networks
• Network features in software apps
• Embedded computing
• Cars, robots, VCRs, microwave ovens
• Fridges, climate control, security