Dual Mode Operation in Operating System

A processor can support two modes of execution:

1. Kernel / Protected / Supervisor / System/Monitor / Privileged mode.
2. User mode / Non-privileged mode

Operating system runs in Kernel mode and user programs run in user mode. Mode bit is used to decide the mode of operating system. If mode bit is 0, it operates in kernel mode. Otherwise it operates in user mode when mode bit is 1.

KERNEL AND ITS TYPES

Kernel is the central component of a computer operating systems. The job performed by the Kernel is to manage the communication between software and the hardware.

Types of Kernel

Monolithic Kernel

• It runs every basic system service like process and memory management, interrupt handling, file system etc. in Kernel space.

Micro Kernel

In micro Kernel architecture, only the most important service are inside Kernel and rest of the OS services are present inside system application program.

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