Computer Science MCQS

remain unchanged

If a scheduler assigns a static priority to a process, it means that the priority of that process will not change throughout its lifetime. It remains fixed and is not affected by any other factors like CPU usage, I/O wait time, or other process-related metrics.

This is in contrast to dynamic priority scheduling, where a process's priority can change based on various criteria.

All of the mentioned

All of the options listed - Windows CE, RTLinux, and VxWorks - are considered real-time operating systems (RTOS). Each is designed to handle time-critical tasks with strict deadlines, making them suitable for applications like industrial control, robotics, and aerospace.

Windows CE: A versatile RTOS developed by Microsoft for embedded systems.

RTLinux: A real-time extension for the Linux kernel.

VxWorks: A widely used commercial RTOS known for its reliability and performance.

Interrupt latency should be minimal for real-time operating systems.

Interrupt latency is the time elapsed between an interrupt occurring and the start of its service routine. In real-time systems, where timely responses are critical, minimizing interrupt latency is crucial to ensure that events are handled promptly. A long interrupt latency can lead to missed deadlines and system failures.

Therefore, real-time operating systems employ techniques like priority-based interrupt handling and efficient interrupt service routines to reduce interrupt latency as much as possible.

less

A hard real-time operating system (RTOS) has less jitter than a soft real-time operating system.

Jitter refers to the variation in response time from one instance to another.

A hard RTOS is designed for systems where missing deadlines can have catastrophic consequences, such as in medical equipment or flight control systems. To ensure this, they have strict timing requirements and minimal jitter.

In contrast, soft RTOS can tolerate some variation in response time without severe consequences.

Therefore, hard RTOS have a much lower tolerance for jitter compared to soft RTOS.

a task must be serviced by its deadline period

In a real-time operating system (RTOS), the critical characteristic is that tasks have strict deadlines that must be met. If a task is not completed within its specified deadline, it is considered a failure. This is unlike general-purpose operating systems where meeting deadlines is not a strict requirement.

Device drivers present a uniform device-access interface to the I/O subsystem.

They act as a bridge between the operating system and hardware devices, providing a standardized way for applications to interact with different types of devices. This abstraction layer simplifies the development of applications and makes the I/O subsystem more manageable.

frame table is a data structure used by the operating system to keep track of physical memory frames. It contains information about the status of each frame, such as whether it's free or allocated to a process, and if allocated, which page is currently stored in it. This information is crucial for memory management and page replacement algorithms.

b) changes

Transient code is temporary code that is loaded into memory only when needed and then removed. As a result, the size of the operating system changes during program execution. It increases when the transient code is loaded and decreases when it is removed.

every address generated by the CPU is being checked against the relocation and limit registers

This is the correct answer.

Relocation register: Holds the base address of a process's memory space.

Limit register: Specifies the maximum size of a process's memory space.

Whenever a process generates an address, the CPU checks it against these registers. If the address is within the process's allowed memory range, it's valid. Otherwise, it's considered an invalid access and is prevented. This mechanism protects the operating system and other processes from being corrupted by a rogue process.

This protection is essential for maintaining system integrity and security.