The Components of an Operating System

The Components of an Operating System

1. NETWORKING

   • Connects computers
     • There will be communication between them
       • When the user has a required subnet
   • Does not share:
     • Memory
     • Peripheral devices
     • A clock
   • Does share:
     • Data with two or more computing devices
   • Use TCP/IP networking protocols
     • TCP uses IP, and IP uses TCP.
       • TCP ensures that every packet/signal, reaches the correct destination.
         • It will keep on sending the same packet until it reaches it's correct destinaion
       • TCP: Trasmission Control Protocol
       • IP: Internet Protocol
   • Masks on an IP network protocol determine how many subnets a user will want to have
     • How many computers will be allowed access to connect to the main network
       • Ex. There are 64 subnets in a Class A network that uses 6 bits for a subnet id
   • Area networks:
     • Local Area Networks (LANs)
       • Computers connected together with Ethernet cables
         • Homes
         • School
         • Small office building
         • Ethernet cables allow communication between computers
     • Wide Area Networks (WANs)
       • Cities
       • Provinces
       • Across the world
         • The largest WAN is the Internet
       • Spans a large geographical area
         • WANs consist of two or moe LANs
   • Things to consider when networking:
     • Routing Stratagies
       • Performed for many kinds of networks
         • Telephone network
         • Electronic Data netwroks
         • Transportation networks
       • Selecting the best paths in a network
     • Connection Stratagies
     • Security
   • Access to shared resources allows:
     • Computation speed up
     • increased data availability
     • Enhanced reliability

2. PROCESS MANAGEMENT

   • Uses resources provided by the OS, whether they are whole programs or fractions of a program, to work on given tasks.
     • Tasks are received by the CPU
       • Central Processing Unit
         • Electronic chip within a computer that carries out instructions of a computer program
     • Executes instructions one after the other in main memory and therefore the program runs.
     • At times if one does not need the whole program code at once
       • A fraction of it is loaded in the main memory
   • Is responsible for:
     • Creation, loading, executing and deletion of processes
     • Processes suspension and resumption
     • Provides a mechanisms for :
       • Process synchronization
       • Process communication: to send data to each other
     • Switching amongst multiple processes in main memory
     • Controls shared data
       • Keeps it consistent
   • The OS must:
     • Set apart resources to processes
       • This is to share and exchange information
     • Protect the resources
       • From being used by other processes
     • Enable synchronization among processes
   • Other information:
     • It is a unit of work in an operating system
     • A process is not a program but instead one instant of a program in execution
     • Deadlock situation:
       • Three running processes will wait forever

3. MAIN MEMORY MANAGEMENT

   • A large array of words or bytes
     • Each have their own address
       • The CPU can access this space
   • a.k.a. Primary memory
   • There is accessible storage provided by the CPU
   • Tasks:
     • Keeping track of memory
       • Usage
       • Who is using it
     • When memory becomes available
       • Will ask itself which process will be loaded in memory
   • Virtual Memory Management
     • A computer’s memory is arranged in a hierarchical manner
       • Starts from fastest registers
         • CPU cache
         • Random Access Memory
         • Disk storage
     • Responsible for:
       • Which component of the computer’s memory is available
       • Which memory will be allocated and dellocated
       • How data will move between components
     • Increases amount of memory available for each process
     • When will the process will require more RAM?
       • If using disks as memory
       • If using slower storage as memory
   • Managing Virtual Addresses
     • If multiple processes are in memory at the same time
       • Must remain separate
     • Having separate address space helps the processes
       • Address is assigned to them
     • This is tracked
       • When the process is finished being used there is space for new processes

4. COMMAND INTERPRETER

   • What is it:
     • User types in commands
       • Interpreter carries them out
     • It translates the commands/instructions
       • So the OS may understand it and executes the command
     • Commands can be given by:
       • The user
       • A program
   • It is not part of the OS even if every OS provides the system programs
     • Some people believe it is a part of the OS
   • It allows users to interact with the OS
     • Windows
       • DOS Command Window
     • Unix/Linux
       • CSHELL
       • Bash
   • Shell or Command-line interpreter:
     • Reads and interprets commands
       • Shell is not part of the operating system
   • Users can submit commands for:
     • Networking
     • Protection
     • I/O Handling
     • Main Memory
     • Process creation and management
     • Secondary Storage Management
     • File System Access

5. SECURITY/PROTECTION SYSTEMS

   • Various processes must be protected from multiple user’s activities
   • There are different types of parts to protect:
     • Hardware resources
     • Kernel code
       • Loaded into a protected area of memory
         • Prevent it from being overwritten by programs or other parts of the operating system
       • Responsible for:
         • Memory management
         • Process and task management
         • Disk management
     • Processes
     • Files
     • Data
     • Against malicious programs
     • Against malware programs
       • With firewalls
       • Use anitvirus software
       • Block spyware
   • Different types of OSs there is some level of security
     • Mac OS X:
       • Itself is designed to protect a users computer
         • Mac: ClamXav antiviruse (used as a backup for security but not necessary)
     • Windows:
       • Windows Defender
       • Microsoft Security Essentials
     • Linux:
       • ClamAV security software
       • Snort security software
   • Security is based on:
     • How the operating system provides access to a number of resources
     • The services provided by the program running
   • This component must:
     • Determine who is allowed access to certain files and who is not
       • With some programs once running have an identity but do not need to request a login
       • With request outside of the computer a login password must be given to authenticate the user

6. FILE MANAGEMENT

   • A file is a collection of related information
     • Can represent programs and data
       • Files can be stored on a disk (secondary storage)
         • Long term storage
         • Must be efficient and convenient
   • Examples of storage media:
     • Magnetic tape
     • Magnetic disk
     • Optical disk
   • Has different properities:
     • Speed
     • Capacity
     • Data transfer rate
     • Access methods
   • File systems are organized into directories
     • Directories contain files and other directions
       • a.k.a. folders, catalogs, drawers
       • Organized into a hierarchical filesystem
         • 1. Directory
           • 2. Subdirectory
         • Parent and Child are used to describe the relationship
   • Tasks:
     • Create
     • Manipulate
     • Delete files
     • Directories

7. I/O SYSTEM MANAGEMENT

   • Input/Output
   • Input only devices:
     • Printers
     • Hard disks
     • Keyboards
     • Mouses
     • Drawing tablets
   • Output only devices:
     • Printers
   • Both Input and Output devices:
     • Hard disks
     • Diskettes
     • Writable CD-ROMs
     • Modems
     • Network Cards
   • Peculiarities
     • The OS hides the peculiarities of the I/O devices from the user
       • Only the device driver knows to whom it is assigned
         • Ensure proper use of devices
         • Prevents errors
   • Tasks
     • Hides the details of hardware devices
     • Manage main memory for the devices
       • Using:
         • Cache
         • Buffer
         • Spooling
     • Maintain and provide device driver interfaces
   • Used by people or systems to communicate with a computer
     • Any program, or device that transfers data
       • To a computer
       • From a computer

8. SECONDARY-STORAGE MANAGEMENT

   • Systems have different levels of storage:
     • Primary
     • Secondary
     • Cache
       • a collection of the same type stored in a hidden/inaccessible place
   • Main memory is
     • Too small to keep all data and programs
       • Main memory minimum: 32 megabytes
     • Data is lost when power is shut off
       • Secondary storage is used to backup main memory
   • Consists of:
     • Tapes
     • Disks
     • Other media designed to hold information
   • Addresses:
     • Each location in storage has its own address
     • Address space:
       • Set of all addresses available to a program
   • OS is responsible for:
     • Free space management
     • Storage allocation and defrag blocks
     • Disk scheduling

9. By: Jessica Kramarczyk

   • NOTE: Assumptions are marked by a star in the bottom- right hand corner of nodes

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