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An operating system is an interface between a computer user and computer hardware. An OS is software that performs all basic functions such as file memory, memory management, process management, handling i / p and o / p, and controls all external devices such as disks, drives, and printers. Controls the execution of all. Types of programs.
Popular Operating Devices:
- Linux OS
- Windows os
Importance of OS:
- memory management
- process management
- device management
- File management
- System performance control
- Job accounts
- AIDS detection error
- Coordination between other software and users
Operating system type
- Batch operating system
- Time-sharing operating system
- Distributed operating system
- Network operating system
- Real time operating system
- This is low level programming and is the heart of the OS.
- The kernel is the interface between the shell and the hardware and it always performs low-level tasks.
- Eg., Memory management, device management.
- Kernel mode is also called privileged mode or supervising mode or system mode.
It is the interface between the user and the operating system.
KERNAL and USER MODE
We want to use dual mode operation because here we have both kernel mode and user mode. For proper execution in OS, there must be a method which is user mode and OS mode. Whenever a computer user executes any code of the application, it is called user mode. Whenever a computer executes a code on behalf of a kernel application. http: //www.kernal mode architecture.
The hardware starts on kernel mode and the user loads the OS after application and then starts.
- Program execution
- I / O Operations
- File system manipulation
- Fault detection
- Resource allocation
CPU SCHEDULING ALGORITHMS
The purpose of CPU scheduling algorithms is to make the system faster, efficient.
- FCFS (FIRST COME FIRST SERVE)
- STF (SHORTEST JOB FIRST)
- round robin