22516 Operating System Unit 1 Notes PDF

                              An operating system (OS) is a vital component of a computer system that acts as an intermediary between users and the computer hardware. It provides a user interface and controls the computer hardware so that software can function.

Key Functions of an Operating System:

1. Processor Management: The OS manages the CPU, deciding which processes get to use it, for how long, and when.
2. Memory Management: The OS is responsible for managing the computer’s memory, which includes the system’s RAM and cache memory.
3. Device Management: The OS manages device communication via their respective drivers. Devices can include hard drives, printers, displays, etc.
4. Storage Management: The OS handles the storage and retrieval of data on storage mediums like hard drives or SSDs.
5. Application Interface: OS provides an interface for applications to access system resources and services.
6. User Interface: This can be command-line based or graphical. This is the interface through which users interact with the computer.
7. File System Management: The OS manages files on different storage devices (like hard drives, SSDs), allowing for creation, deletion, reading, and writing.
8. Security and Access Control: The OS ensures unauthorized users do not access the system and protects against malware and other security threats.

Types of Operating Systems:

1. Batch Operating System: Executes a series of jobs all at once.
2. Multiprogramming Operating System: Manages multiple jobs by having one job use the CPU while others are waiting for I/O operations to complete.
3. Multitasking Operating System: Allows multiple tasks to run simultaneously on the machine.
4. Multithreading Operating System: Allows different parts of a single program (threads) to run concurrently.
5. Real-time Operating System (RTOS): Used for real-time applications where data processing must be done within certain time constraints.
6. Distributed Operating System: Runs on multiple machines with the aim of achieving a common goal.
7. Embedded Operating System: Designed for special-purpose applications and used in appliances, cars, and other non-computer devices.

Popular Operating Systems:

1. Microsoft Windows: A series of OSes from Microsoft, predominantly used on personal computers.
2. Unix/Linux: Unix is an OS that began in the 1960s and has influenced many others. Linux is a Unix-like OS that's open source.
3. Mac OS: Developed by Apple Inc. for their Macintosh line of computers.
4. Android: A mobile OS based on the Linux kernel, primarily designed for touchscreen devices.
5. iOS: Developed by Apple for its mobile devices like the iPhone and iPad.

Conclusion:

In essence, an operating system acts as a bridge between the user and the computer hardware. It provides a set of services that simplify the creation and execution of application programs and effectively manages the hardware resources of a computer.