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Operating Systems Basics
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1
Question
What is an operating system (OS)?
Answer
System software that manages hardware and provides services for applications
2
Question
What is one primary role of an OS besides running programs?
Answer
To manage resources (CPU, memory, I/O) fairly and efficiently
3
Question
Name three common examples of operating systems.
Answer
Windows, Linux, macOS
4
Question
What does the OS do in multitasking environments?
Answer
Allows multiple programs to run in their own space and communicate
5
Question
What is a system call?
Answer
A programmatic request by a process to the kernel for a service
6
Question
What is the kernel’s main purpose?
Answer
Bridge between software and hardware; manages resources
7
Question
Which kernel structure runs most services in kernel space and is fast but hard to maintain?
Answer
Monolithic structure
8
Question
What is a micro-kernel?
Answer
A kernel that runs only essential services in kernel space; other services run in user space
9
Question
What is a real-time OS (RTOS) designed to guarantee?
Answer
Timely task completion with predictable scheduling
10
Question
Differentiate hard RTOS from soft RTOS.
Answer
Hard RTOS has strict deadlines; soft RTOS allows some flexibility
11
Question
What is the difference between a process and a thread?
Answer
Process is an executing program with its own memory; a thread is a path of execution within a process sharing memory
12
Question
What is a Process Control Block (PCB)?
Answer
A data structure holding process information (PID, state, CPU info, etc.)
13
Question
Which scheduling metric measures total time from submission to completion?
Answer
Turnaround time
14
Question
What is the formula for turnaround time?
Answer
Turnaround Time = Waiting Time + CPU Time + I/O Time
15
Question
What does CPU utilization aim to maximize in scheduling?
Answer
Keep the CPU as busy as possible
16
Question
In FCFS scheduling, what is a major drawback?
Answer
Convoy effect (long first job can delay others)
17
Question
What is the key idea of Shortest Job First (SJF) non-preemptive scheduling?
Answer
Always run the process with the smallest burst time next
18
Question
What issue can arise with SJF scheduling?
Answer
Starvation of long processes
19
Question
What is a system call example used to open files?
Answer
open()
20
Question
What does the fork() system call do in many OSs?
Answer
Creates a new process by duplicating the calling process
21
Question
What is the role of memory management in an OS?
Answer
Allocate and deallocate memory to processes; manage paging/virtual memory
22
Question
What is the purpose of I/O device management?
Answer
Coordinate use of input/output devices and drivers
23
Question
What is the concept of virtual memory?
Answer
A technique to use disk space as an extension of RAM
24
Question
What is the difference between user-level threads and kernel-level threads?
Answer
ULT are managed by user space; KLT are scheduled by the kernel
25
Question
What is a hybrid-many-to-many threading model?
Answer
Multiple user threads mapped to multiple kernel threads
26
Question
What is booting in the context of OS?
Answer
Starting a computer and loading the OS into memory
27
Question
What is a dual-boot setup?
Answer
Installing two OSes on the same machine with a boot manager to choose at startup
28
Question
What is the role of system software like the OS?
Answer
Provide a platform for applications and manage hardware resources
29
Question
What is the purpose of file system management?
Answer
Create, read, write, and organize files with permissions
30
Question
What does I/O management handle in OS functions?
Answer
Coordinating device communication, buffering, and queues