Computer Systems 6.1&6.2

Notes from 6.1 and 6.2

What is the primary role of the Operating System (OS)?

To act as an intermediary between the user/applications and the computer hardware.

Name three core functions of an Operating System.

Memory Management, Peripheral Management, Multitasking, Security, and User Interface.

What is the Kernel in an Operating System?

The core component that has complete control over the system and operates with the highest level of privileges in Kernel Space.

What is the main characteristic of a Monolithic Kernel?

All essential services (drivers, file system, etc.) run together in one large block within Kernel Space.

What is the key advantage of a Monolithic Kernel?

Better performance due to low communication overhead.

Why is a Microkernel generally considered more stable than a Monolithic kernel?

Services like device drivers run in User Space, isolating them so a crash in one service doesn't crash the entire kernel.

What is the main drawback of the Microkernel design?

Performance overhead because user space services must use system calls to communicate with the core kernel.

Which kernel design architecture attempts to balance speed and stability by placing only key services in the kernel?

The Hybrid Kernel.

What is the definition of a Process in an operating system?

An instance of a computer program being executed, including its code, data, and resources.

In the process life cycle, what does the Ready state mean?

The process is loaded into RAM and is waiting to be assigned to the CPU for execution.

What causes a process to transition into the Waiting (or Blocked) state?

It is waiting for an I/O event to be completed (e.g., disk read, printer output).

What data structure is maintained by the OS to store all management information for a single process?

The Process Control Block (PCB).

Name two crucial pieces of information stored in the Process Control Block (PCB).

Process State, Program Counter (PC), or CPU Register values.

What is a quantum (or time slice) in process scheduling?

A fixed amount of CPU time given to a process before it is switched out.

What is the operational mechanism used to switch the CPU from one process to another?

A Context Switch.

Why is saving the data of a suspended process into its PCB important during a Context Switch?

It ensures the process can resume exactly where it left off without losing any data.