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Introduction to Operating System

  • An operating system is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware.

Functionalities:

Resource Management:

  • When parallel accessing happens in the OS means when multiple users are accessing the system the OS works as Resource Manager, Its responsibility is to provide hardware to the user.
  • It decreases the load in the system.

Process Management:

  • It includes various tasks like scheduling, termination of the process.
  • OS manages various tasks at a time. Here CPU Scheduling happens means all the tasks would be done by the many algorithms that use for scheduling.

Storage Management:

  • The file system mechanism used for the management of the storage. NIFS, CFS, CIFS, NFS, etc. are some file systems.
  • All the data stores in various tracks of Hard disks that all managed by the storage manager. It included Hard Disk.

Memory Management:

  • Refers to the management of primary memory.
  • The operating system has to keep track, how much memory has been used and by whom. It has to decide which process needs memory space and how much.
  • OS also has to allocate and deallocate the memory space.

Security/ Privacy Management:

  • Privacy is also provided by the Operating system by means of passwords so that unauthorized applications can’t access programs or data.
  • For example, Windows uses Kerberos authentication to prevent unauthorized access to data.

Types of Operating System

1. Batch Operating System

  • This type of operating system does not interact with the computer directly.
  • There is an operator which takes similar jobs having the same requirement and group them into batches.
  • It is the responsibility of the operator to sort jobs with similar needs.
  • Examples of Batch based Operating System: Payroll System

2. Time Sharing Operating System

  • Each task is given some time to execute so that all the tasks work smoothly.
  • Each user gets the time of CPU as they use a single system.
  • After this time interval is over OS switches over to the next task.
  • Examples of Time-Sharing OSs are: Unix, etc.

3. Distributed Operating System

  • The Distributed Operating system is not installed on a single machine, it is divided into parts, and these parts are loaded on different machines.
  • A part of the distributed Operating system is installed on each machine to make their communication possible.
  • Examples of Distributed Operating System are- LOCUS, etc.

4. Network Operating System

  • These systems run on a server and provide the capability to manage data, users, groups, security, applications, and other networking functions.
  • These types of operating systems allow shared access of files, printers, security, applications, and other networking functions over a small private network.
  • Examples of Network Operating System are: Linux.

5. Real-Time Operating System

  • These types of OSs serve real-time systems.
  • The time interval required to process and respond to inputs is very small. This time interval is called response time.

Types of Memory

RAM

  • It is also called read-write memory or the main memory or the primary memory.
  • The programs and data that the CPU requires during the execution of a program are stored in this memory.
  • It is a volatile memory as the data is lost when the power is turned off.
  • Types:
  • SRAM:
    • Used for cache.
  • DRAM:
    • Used for main memory.

ROM

  • Stores crucial information essential to operate the system, like the program essential to boot the computer.
  • It is not volatile.
  • Always retains its data.
  • Used in embedded systems or where the programming needs no change.
  • Used in calculators and peripheral devices.
  • Types: PROM, EPROM, EEPROM

Difference between 32-bit and 64-bit Operating System

  • A 32-bit system can access 2^32 different memory addresses, i.e 4 GB of RAM or physical memory ideally, it can access more than 4 GB of RAM also.

  • A 64-bit system can access 2^64 different memory addresses, i.e actually 18-Quintillion bytes of RAM. In short, any amount of memory greater than 4 GB can be easily handled by it.

Some Terminologies

  • Multiprogramming : Multiprogramming is known as keeping multiple programs in the main memory at the same time ready for execution.
  • Multiprocessing : A computer using more than one CPU at a time.
  • Multitasking : Multitasking is nothing but multiprogramming with a Round-robin scheduling algorithm.
  • Multithreading: It is an extension of multitasking.