Privileged and Non privileged mode of operating System using Previous year gate question Paper 1999

Privileged and Non privileged mode of operating System using Previous year gate question Paper 1999

Certainly! Let’s explore the concept of Privileged and Non-Privileged Modes in operating systems, referencing a relevant question from the GATE CSE 1999 exam.

Understanding CPU Modes

Modern CPUs operate in at least two distinct modes to ensure system stability and security:

1. Privileged Mode (Kernel Mode):

   • Access Level: Full access to all system resources.

   • Purpose: Executes critical system tasks like managing hardware, memory, and system calls.

   • Example Operations: Modifying system registers, handling interrupts, and performing I/O operations.

2. Non-Privileged Mode (User Mode):

   • Access Level: Restricted access to system resources.

   • Purpose: Runs user applications, preventing them from directly interfering with system operations.

   • Example Operations: Executing application code, performing standard computations.

This separation ensures that user applications cannot inadvertently or maliciously disrupt core system functions.

GATE CSE 1999 – Relevant Question

Question:

A multi-user, multi-processing operating system cannot be implemented on hardware that does not support:

A. Address translation
B. DMA for disk transfer
C. At least two modes of CPU execution (privileged and non-privileged)
D. Demand paging

Correct Answer: C. At least two modes of CPU execution (privileged and non-privileged)

Explanation:

Implementing a multi-user, multi-processing operating system necessitates a clear distinction between user-level and system-level operations. Without hardware support for at least two CPU execution modes, the operating system cannot enforce this separation, leading to potential security vulnerabilities and system instability.

Why Are These Modes Essential?

• Security: Prevents user applications from executing critical system instructions that could compromise the system.

• Stability: Ensures that errors in user applications do not affect the overall system operation.

• Controlled Access: Allows the operating system to manage resources efficiently and safely.

Further Reading

For a more in-depth understanding, consider exploring the following resource:

• Privileged and Non-Privileged Instructions in Operating Systems

Feel free to ask if you need more information or have other questions related to operating systems or GATE exam preparation!

Privileged and Non privileged mode of operating System using Previous year gate question Paper 1999

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