OS Fundamentals

An operating system manages hardware resources and provides services for programs.

Key Functions

• Process Management — scheduling, multitasking
• Memory Management — allocation, virtual memory
• File System — organizing storage
• Security — access control

Syntax

COMPUTER-SCIENCE

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# Process states
New → Ready → Running → Terminated
                ↓
              Waiting → Ready

Process Scheduling Concept

PYTHON

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# Round Robin scheduling
def round_robin(processes, quantum):
    n = len(processes)
    remaining = [p[1] for p in processes]
    time = 0

    while True:
        done = True
        for i in range(n):
            if remaining[i] > 0:
                done = False
                if remaining[i] > quantum:
                    time += quantum
                    remaining[i] -= quantum
                else:
                    time += remaining[i]
                    remaining[i] = 0
                    print(f"{processes[i][0]} completed at t={time}")
        if done:
            break

processes = [("P1", 10), ("P2", 4), ("P3", 6)]
round_robin(processes, quantum=3)

Try It Yourself

Practice

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Exercise

What are the main functions of an OS?

Answer

Process management, memory management, file system management, security, and I/O management.

Quick Quiz

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What is multitasking?

Running one program

Running multiple programs simultaneously

Running a program faster

Running no programs

Multitasking allows multiple processes to share CPU time.

Retry Quiz

Interview Questions

What is a process vs a thread?

A process is an independent program with its own memory. A thread shares memory with other threads in the same process. Threads are lightweight.

Tutorial Complete

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