Question

Differentiate between monolithic, layered and microkernel structure of OS.

Answer 1

Structure	Description	Advantages	Disadvantages
Monolithic	A monolithic operating system is a single, large program that includes all of the operating system's functionality, such as process management, memory management, and device drivers, in a single address space.	Efficient communication and resource sharing between components, high performance, easy to implement.	Difficult to modify or extend, errors in one part of the system can affect the entire system, less secure due to a lack of isolation between components.
Layered	A layered operating system consists of several layers, where each layer provides a specific set of services to the layer above it. The lowest layer interacts directly with the hardware, while the higher layers provide more abstract services to the user.	Modularity and flexibility, easier to modify or extend, more secure due to isolation between layers.	Reduced performance due to communication overhead between layers, complexity in managing dependencies between layers.
Microkernel	A microkernel operating system has a minimal kernel that provides only essential operating system services, such as process management and inter-process communication, while other services, such as device drivers and file systems, are implemented as user-level processes or modules.	Modularity and flexibility, easier to modify or extend, more secure due to isolation between services, higher reliability due to smaller kernel size.	Reduced performance due to communication overhead between kernel and user-level processes, complexity in managing communication between user-level processes.