Operating System MCQs

Important computer science MCQS, Operating system MCQS for lecturer Computer, Computer Instructor TGT Computer etc

 The information about all files is kept in __

A. a) operating system
B. b) separate directory structure
C. c) swap space
D. d) none of the mentioned
Correct answer is: B. b) separate directory structure
b) separate directory structure

The information about all files is kept in a separate directory structure. This structure organizes files and directories hierarchically, making it easy to locate and manage files.

If the sum of the working – set sizes increases, exceeding the total number of available frames __

A. a) the operating system selects a process to suspend
B. b) the system crashes
C. c) then the process crashes
D. d) the memory overflows
Correct answer is: A. a) the operating system selects a process to suspend
the operating system selects a process to suspend

This is correct.

Working set is the set of memory pages actively used by a process. If the total size of all active processes' working sets exceeds the available physical memory, the operating system faces a memory shortage.

To prevent system slowdown or crashes due to excessive page swapping (thrashing), the operating system typically suspends one or more processes. This frees up their memory frames, reducing the overall memory demand and allowing the remaining processes to continue operating efficiently.

The priority of a process will __ if the scheduler assigns it a static priority.

A. a) depends on the operating system
B. b) change
C. c) remain unchanged
D. d) none of the mentioned
Correct answer is: C. c) remain unchanged
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.

Which one of the following is a real time operating system?

A. a) Windows CE
B. b) RTLinux
C. c) VxWorks
D. d) All of the mentioned
Correct answer is: D. d) All of the mentioned
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.

 For real time operating systems, interrupt latency should be __

A. a) zero
B. b) minimal
C. c) maximum
D. d) dependent on the scheduling
Correct answer is: B. b) minimal
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.

 Hard real time operating system has __ jitter than a soft real time operating system.

A. a) equal
B. b) more
C. c) less
D. d) none of the mentioned
Correct answer is: C. c) less
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.

 In real time operating system __

A. a) process scheduling can be done only once
B. b) all processes have the same priority
C. c) kernel is not required
D. d) a task must be serviced by its deadline period
Correct answer is: D. d) a task must be serviced by its deadline period
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.

The _ presents a uniform device-access interface to the I/O subsystem, much as system calls provide a standard interface between the application and the operating system.

A. a) Device drivers
B. b) I/O systems
C. c) Devices
D. d) Buses
Correct answer is: A. a) Device drivers
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.

The operating system maintains a __ table that keeps track of how many frames have been allocated, how many are there, and how many are available.

A. a) memory
B. b) mapping
C. c) page
D. d) frame
Correct answer is: D. d) frame
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.

Using transient code, _ the size of the operating system during program execution.

A. a) maintains
B. b) changes
C. c) increases
D. d) decreases
Correct answer is: B. b) changes
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.

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