Dual Mode Operations in OS - User Mode, System Mode & Kernel Transitions

Explore the essentials of dual mode operations, including an in-depth look at user mode, system mode, and how transitions occur from user to kernel mode. This presentation is perfect for anyone interested in operating system fundamentals, with clear explanations and visual aids to help demystify complex topics. Learn the importance of these modes in ensuring system security, efficiency, and stability.

1. Dual Mode Operations in OS: User Mode, System Mode & Kernel Transitions

2. DUAL MODE OPERATIONS

3. USER MODE When the computer system run user application like creating a text document or using an application program. Then the system is in user mode. When the user application requests for a service from the operating system or an interrupt occurs, then there will be a transition from user to kernel mode to fulfill the requests.

4. SYSTEM MODE When system boots then hardware starts in System mode and when operating system is loaded then it start user application in user mode. To provide protection to the hardware, we have privileged instructions which execute only in System mode. If user attempt to run privileged instruction in user mode, then it will treat instruction as illegal and traps to OS.

5. TRANSITION FROM USER TO KERNEL MODE Typically, there are 2 points of switching from user to kernel mode: When calling a System Call When an exception comes To switch from user mode to kernel mode, mode-bit should be 0 and To switch from kernel mode to user mode, mode-bit should be 1.

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