The Components of an Operating System

NETWORKING
1. Connects computers
  1. There will be communication between them
    1. When the user has a required subnet
2. Does not share:
  1. Memory
  2. Peripheral devices
  3. A clock
3. Does share:
  1. Data with two or more computing devices
4. Use TCP/IP networking protocols
  1. TCP uses IP, and IP uses TCP.
    1. TCP ensures that every packet/signal, reaches the correct destination.
      1. It will keep on sending the same packet until it reaches it's correct destinaion
    2. TCP: Trasmission Control Protocol
    3. IP: Internet Protocol
5. Masks on an IP network protocol determine how many subnets a user will want to have
  1. How many computers will be allowed access to connect to the main network
    1. Ex. There are 64 subnets in a Class A network that uses 6 bits for a subnet id
6. Area networks:
  1. Local Area Networks (LANs)
    1. Computers connected together with Ethernet cables
      1. Homes
      2. School
      3. Small office building
      4. Ethernet cables allow communication between computers
  2. Wide Area Networks (WANs)
    1. Cities
    2. Provinces
    3. Across the world
      1. The largest WAN is the Internet
    4. Spans a large geographical area
      1. WANs consist of two or moe LANs
7. Things to consider when networking:
  1. Routing Stratagies
    1. Performed for many kinds of networks
      1. Telephone network
      2. Electronic Data netwroks
      3. Transportation networks
    2. Selecting the best paths in a network
  2. Connection Stratagies
  3. Security
8. Access to shared resources allows:
  1. Computation speed up
  2. increased data availability
  3. Enhanced reliability
PROCESS MANAGEMENT
1. Uses resources provided by the OS, whether they are whole programs or fractions of a program, to work on given tasks.
  1. Tasks are received by the CPU
    1. Central Processing Unit
      1. Electronic chip within a computer that carries out instructions of a computer program
  2. Executes instructions one after the other in main memory and therefore the program runs.
  3. At times if one does not need the whole program code at once
    1. A fraction of it is loaded in the main memory
2. Is responsible for:
  1. Creation, loading, executing and deletion of processes
  2. Processes suspension and resumption
  3. Provides a mechanisms for :
    1. Process synchronization
    2. Process communication: to send data to each other
  4. Switching amongst multiple processes in main memory
  5. Controls shared data
    1. Keeps it consistent
3. The OS must:
  1. Set apart resources to processes
    1. This is to share and exchange information
  2. Protect the resources
    1. From being used by other processes
  3. Enable synchronization among processes
4. Other information:
  1. It is a unit of work in an operating system
  2. A process is not a program but instead one instant of a program in execution
  3. Deadlock situation:
    1. Three running processes will wait forever
MAIN MEMORY MANAGEMENT
1. A large array of words or bytes
  1. Each have their own address
    1. The CPU can access this space
2. a.k.a. Primary memory
3. There is accessible storage provided by the CPU
4. Tasks:
  1. Keeping track of memory
    1. Usage
    2. Who is using it
  2. When memory becomes available
    1. Will ask itself which process will be loaded in memory
5. Virtual Memory Management
  1. A computer’s memory is arranged in a hierarchical manner
    1. Starts from fastest registers
      1. CPU cache
      2. Random Access Memory
      3. Disk storage
  2. Responsible for:
    1. Which component of the computer’s memory is available
    2. Which memory will be allocated and dellocated
    3. How data will move between components
  3. Increases amount of memory available for each process
  4. When will the process will require more RAM?
    1. If using disks as memory
    2. If using slower storage as memory
6. Managing Virtual Addresses
  1. If multiple processes are in memory at the same time
    1. Must remain separate
  2. Having separate address space helps the processes
    1. Address is assigned to them
  3. This is tracked
    1. When the process is finished being used there is space for new processes
COMMAND INTERPRETER
1. What is it:
  1. User types in commands
    1. Interpreter carries them out
  2. It translates the commands/instructions
    1. So the OS may understand it and executes the command
  3. Commands can be given by:
    1. The user
    2. A program
2. It is not part of the OS even if every OS provides the system programs
  1. Some people believe it is a part of the OS
3. It allows users to interact with the OS
  1. Windows
    1. DOS Command Window
  2. Unix/Linux
    1. CSHELL
    2. Bash
4. Shell or Command-line interpreter:
  1. Reads and interprets commands
    1. Shell is not part of the operating system
5. Users can submit commands for:
  1. Networking
  2. Protection
  3. I/O Handling
  4. Main Memory
  5. Process creation and management
  6. Secondary Storage Management
  7. File System Access
SECURITY/PROTECTION SYSTEMS
1. Various processes must be protected from multiple user’s activities
2. There are different types of parts to protect:
  1. Hardware resources
  2. Kernel code
    1. Loaded into a protected area of memory
      1. Prevent it from being overwritten by programs or other parts of the operating system
    2. Responsible for:
      1. Memory management
      2. Process and task management
      3. Disk management
  3. Processes
  4. Files
  5. Data
  6. Against malicious programs
  7. Against malware programs
    1. With firewalls
    2. Use anitvirus software
    3. Block spyware
3. Different types of OSs there is some level of security
  1. Mac OS X:
    1. Itself is designed to protect a users computer
      1. Mac: ClamXav antiviruse (used as a backup for security but not necessary)
  2. Windows:
    1. Windows Defender
    2. Microsoft Security Essentials
  3. Linux:
    1. ClamAV security software
    2. Snort security software
4. Security is based on:
  1. How the operating system provides access to a number of resources
  2. The services provided by the program running
5. This component must:
  1. Determine who is allowed access to certain files and who is not
    1. With some programs once running have an identity but do not need to request a login
    2. With request outside of the computer a login password must be given to authenticate the user
FILE MANAGEMENT
1. A file is a collection of related information
  1. Can represent programs and data
    1. Files can be stored on a disk (secondary storage)
      1. Long term storage
      2. Must be efficient and convenient
2. Examples of storage media:
  1. Magnetic tape
  2. Magnetic disk
  3. Optical disk
3. Has different properities:
  1. Speed
  2. Capacity
  3. Data transfer rate
  4. Access methods
4. File systems are organized into directories
  1. Directories contain files and other directions
    1. a.k.a. folders, catalogs, drawers
    2. Organized into a hierarchical filesystem
      1. 1. Directory
        2. Subdirectory
      2. Parent and Child are used to describe the relationship
5. Tasks:
  1. Create
  2. Manipulate
  3. Delete files
  4. Directories
I/O SYSTEM MANAGEMENT
1. Input/Output
2. Input only devices:
  1. Printers
  2. Hard disks
  3. Keyboards
  4. Mouses
  5. Drawing tablets
3. Output only devices:
  1. Printers
4. Both Input and Output devices:
  1. Hard disks
  2. Diskettes
  3. Writable CD-ROMs
  4. Modems
  5. Network Cards
5. Peculiarities
  1. The OS hides the peculiarities of the I/O devices from the user
    1. Only the device driver knows to whom it is assigned
      1. Ensure proper use of devices
      2. Prevents errors
6. Tasks
  1. Hides the details of hardware devices
  2. Manage main memory for the devices
    1. Using:
      1. Cache
      2. Buffer
      3. Spooling
  3. Maintain and provide device driver interfaces
7. Used by people or systems to communicate with a computer
  1. Any program, or device that transfers data
    1. To a computer
    2. From a computer
SECONDARY-STORAGE MANAGEMENT
1. Systems have different levels of storage:
  1. Primary
  2. Secondary
  3. Cache
    1. a collection of the same type stored in a hidden/inaccessible place
2. Main memory is
  1. Too small to keep all data and programs
    1. Main memory minimum: 32 megabytes
  2. Data is lost when power is shut off
    1. Secondary storage is used to backup main memory
3. Consists of:
  1. Tapes
  2. Disks
  3. Other media designed to hold information
4. Addresses:
  1. Each location in storage has its own address
  2. Address space:
    1. Set of all addresses available to a program
5. OS is responsible for:
  1. Free space management
  2. Storage allocation and defrag blocks
  3. Disk scheduling
By: Jessica Kramarczyk
1. NOTE: Assumptions are marked by a star in the bottom- right hand corner of nodes

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	Created by Jessica K over 6 years ago