Q.1 What is the primary characteristic of a Real-Time Operating System (RTOS)?
High throughput
Guaranteed response time
Low power consumption
Ease of programming
Explanation - RTOS focuses on deterministic behavior, ensuring tasks meet deadlines with predictable response times.
Correct answer is: Guaranteed response time
Q.2 Which of the following is an example of a hard real-time system?
Video streaming
Airbag system in cars
Email client
Word processor
Explanation - Airbag deployment must occur within strict deadlines, making it a hard real-time application.
Correct answer is: Airbag system in cars
Q.3 In a soft real-time system, missing a deadline results in:
System crash
Reduced quality of service
Task starvation
System reboot
Explanation - Soft real-time systems tolerate occasional deadline misses, but it impacts quality rather than correctness.
Correct answer is: Reduced quality of service
Q.4 Which scheduling algorithm is most commonly used in RTOS?
Round Robin
Earliest Deadline First (EDF)
Shortest Job First
Priority Scheduling
Explanation - EDF is widely used as it schedules tasks based on the earliest deadlines, ensuring timeliness.
Correct answer is: Earliest Deadline First (EDF)
Q.5 What does 'deterministic behavior' mean in RTOS?
Tasks run randomly
Execution time is predictable
CPU utilization is always high
Memory is unlimited
Explanation - Determinism means the system produces predictable results in terms of timing and execution.
Correct answer is: Execution time is predictable
Q.6 Which type of scheduling guarantees deadlines in hard real-time systems?
Best Effort
Non-preemptive scheduling
Preemptive priority scheduling
First-Come-First-Served
Explanation - Preemptive scheduling allows higher priority tasks to interrupt lower ones, ensuring deadlines are met.
Correct answer is: Preemptive priority scheduling
Q.7 Which of the following is NOT a requirement of RTOS?
Predictability
Reliability
Determinism
High throughput
Explanation - Throughput is important in general-purpose OS, but RTOS emphasizes predictability and reliability.
Correct answer is: High throughput
Q.8 Which of the following is an example of a soft real-time system?
Nuclear reactor control
Medical life-support system
Online video conferencing
Aircraft autopilot
Explanation - Occasional delay in video conferencing only reduces quality but does not cause catastrophic failure.
Correct answer is: Online video conferencing
Q.9 Which RTOS feature ensures that high-priority tasks get CPU access before lower-priority tasks?
Priority Inversion
Priority Inheritance
Preemptive Scheduling
Round Robin
Explanation - Preemptive scheduling interrupts lower-priority tasks to allow higher-priority ones to execute.
Correct answer is: Preemptive Scheduling
Q.10 What is priority inversion in RTOS?
Higher priority task preempts lower one
Lower priority task holds a resource needed by a higher one
Tasks switch priorities dynamically
Deadlines are missed due to CPU overload
Explanation - Priority inversion happens when a high-priority task waits because a low-priority task holds a required resource.
Correct answer is: Lower priority task holds a resource needed by a higher one
Q.11 What is used to solve priority inversion?
Priority Queues
Priority Inheritance
Round Robin Scheduling
Time Slicing
Explanation - In priority inheritance, the lower-priority task temporarily inherits the higher priority to finish quickly.
Correct answer is: Priority Inheritance
Q.12 What is the main difference between general-purpose OS and RTOS?
RTOS is slower
RTOS is deterministic
General OS consumes less memory
General OS always uses preemptive scheduling
Explanation - Unlike general-purpose OS, RTOS ensures predictable response times.
Correct answer is: RTOS is deterministic
Q.13 Which of these is NOT a real-time scheduling algorithm?
Rate Monotonic Scheduling
Earliest Deadline First
Least Laxity First
First-Come-First-Served
Explanation - FCFS is used in general-purpose OS, not suitable for real-time requirements.
Correct answer is: First-Come-First-Served
Q.14 Rate Monotonic Scheduling (RMS) assigns priorities based on:
Deadline proximity
Task frequency
CPU usage
Memory requirements
Explanation - In RMS, tasks with shorter periods (higher frequency) get higher priority.
Correct answer is: Task frequency
Q.15 Which of these devices is most likely to use an RTOS?
Smartwatch
Word Processor
Web Browser
Text Editor
Explanation - Embedded devices like smartwatches require real-time task handling, hence RTOS.
Correct answer is: Smartwatch
Q.16 In RTOS, context switching should be:
Slow
Predictable and fast
Random
Avoided at all costs
Explanation - RTOS needs efficient context switching to maintain task deadlines.
Correct answer is: Predictable and fast
Q.17 What does 'latency' in RTOS refer to?
Delay before a task starts execution
Time to complete a task
CPU idle time
Memory access time
Explanation - Latency is the response time between event occurrence and task execution.
Correct answer is: Delay before a task starts execution
Q.18 What is the main drawback of Earliest Deadline First (EDF) scheduling?
Not optimal
Complex to implement
Not preemptive
Consumes more CPU
Explanation - EDF provides optimal scheduling but requires complex dynamic priority management.
Correct answer is: Complex to implement
Q.19 Which RTOS concept prevents low-priority tasks from blocking high-priority tasks indefinitely?
Priority Inversion
Priority Inheritance
Deadlock Prevention
Aging
Explanation - Priority inheritance ensures higher priority tasks eventually get required resources.
Correct answer is: Priority Inheritance
Q.20 Which component of RTOS is responsible for task switching?
Scheduler
Semaphore
Monitor
Dispatcher
Explanation - The scheduler decides which task runs and handles context switching.
Correct answer is: Scheduler
Q.21 Which type of kernel is most commonly used in RTOS?
Monolithic Kernel
Microkernel
Hybrid Kernel
Exokernel
Explanation - Microkernels are preferred in RTOS due to their small size and modular design.
Correct answer is: Microkernel
Q.22 What ensures synchronization between tasks in RTOS?
Paging
Semaphores
Virtual Memory
Deadlocks
Explanation - Semaphores help synchronize tasks and manage shared resources in RTOS.
Correct answer is: Semaphores
Q.23 What is the purpose of a watchdog timer in RTOS?
To measure CPU usage
To reset system on failure
To increase task priority
To schedule tasks
Explanation - Watchdog timers detect failures or hangs and reset the system to ensure reliability.
Correct answer is: To reset system on failure
Q.24 In real-time systems, 'jitter' refers to:
Average execution time
Variability in response time
CPU idle cycles
Task starvation
Explanation - Jitter is the deviation in task response time from its expected value.
Correct answer is: Variability in response time
Q.25 Which of these is NOT an RTOS?
VxWorks
FreeRTOS
Windows XP
QNX
Explanation - Windows XP is a general-purpose OS, not designed for real-time tasks.
Correct answer is: Windows XP