Operating Systems : The Processes

Operating systems basically is a layer between the complex hardware and the application(interface) that users are familiar with. Operating system is a basic fundamental unit  for multitasking or multi-operating.

For example, I am typing this blog, while listening to music. So my OS is currently tasking out two processes.

I have seen many people getting confusing  Operating system with kernel. Basically kernel is the heart of the OS, with utmost basic facilities. When we add more utilities to it, it becomes a OS.
For example Linux is a kernel , but when we add utilities like a text editor, compiler etc, it becomes an OS like Ubuntu.


Examples of different Operating Systems are:
1.Windows.
2.Linux
3.Android
4.Mac
and many more...

A process is technically defined as unit of activity characterized by execution of sequence of instructions,a current state and associated state of system resources.
To put in simpler words a process is anything that can be assigned to and executed on the processor.

Here,we must be very clear with the Process Program fiasco. A process is not a program, but just a instance of a program. When you code, that is a program but when you run it  on the processor its a process.

Hence, a process is a program under execution.

To differentiate or put in common terms, what you carry in your pendrive can be termed as a program, when you connect that pendrive and run your program, that's a process.



Every person we know,has certain characteristics like their name, age, gender etc. This characterization helps classification as well as serves the purpose of indentification.
Similarly a process also has certain attributes associated to it which makes it easy to identify, classify and keep a track of the processes.

This 'identification unit' associated with the process  is  called as the  'Process Control Block' or PCB.



Attributes of the PCB:

Identifier :A unique indentifier is associated with the process, to distinguish it from other processes,

State:Whether the process is Running or Blocked.

Priority:It tells the significance of the concerned process with respect to all the other processes running along.

 Program counter:It holds the address of the next instruction to be executed.

 Memory pointer:Includes pointers to program code.

Context data: This is the data present in the processor register, while the concerned process is being executed on the processor.

 I/O status info:It has all I/O device information, like I/O requests etc.

Accounting info:It has information such as processor time, clock time etc.



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