Notes

it should start in kernel mode to load the bootloader safely into the RAM and then the kernel has security checks on the entire system and the computer starts

A command interpreter allows the user to interact with a program using commands in the form of text lines. It was frequently used until the 1970’s. However, in modern times many command interpreters are replaced by graphical user interfaces and menu-driven interfaces.


Context Switching involves storing the context or state of a process so that it can be reloaded when required and execution can be resumed from the same point as earlier. This is a feature of a multitasking operating system and allows a single CPU to be shared by multiple processes.

A critical section is a segment of code which can be accessed by a signal process at a specific point of time. The section consists of shared data resources that required to be accessed by other processes.

The entry to the critical section is handled by the wait() function, and it is represented as P().
The exit from a critical section is controlled by the signal() function, represented as V().
In the critical section, only a single process can be executed. Other processes, waiting to execute their critical section, need to wait until the current process completes its execution.

Process Synchronization is the task of coordinating the execution of processes in a way that no two processes can have access to the same shared data and resources.

It is specially needed in a multi-process system when multiple processes are running together, and more than one processes try to gain access to the same shared resource or data at the same time.