Operating Systems Fundamentals Flashcards
(35 cards)
What is an Operating System (OS)?
An OS controls hardware and software, working between the user and the computer
It manages hardware resources, processes, memory, files, and I/O devices.
Lets users and applications to interact with the computer system effectively.
What are the main objectives of an operating system?
Easy to use, works fast, and can improve over time.
Objectives: Resource management, user interface, security, and hardware abstraction.
Maximizes system performance and user productivity
What are the four key components of a computer system?
Hardware
Operating System
Application Programs
Users
OS controls hardware and provides services to applications.
Separates user-level interaction from hardware complexity.
What are the main stages in the evolution of operating systems?
Serial Processing: One job at a time, no OS help
Simple Batch Systems: Jobs run in batches, with little user interaction
Multiprogrammed Batch Systems: Several jobs in memory, CPU switches between them
Time-Sharing Systems: Many users share the system, each gets a short time to run
Each stage aimed to improve efficiency, usability, and multitasking.
What is serial processing in operating systems?
Jobs run one after another, with no overlap
No OS or automation, manual setup and execution.
Inefficient due to long setup times and idle CPU.
What is the primary feature of a batch processing system?
Jobs are grouped and run one after another, with a monitor guiding the order
The OS manages job scheduling, spooling, and sequential execution.
Increases throughput and reduces idle time compared to serial processing.
What is multiprogramming in an OS?
Several programs stay in memory at once so the CPU is always busy
The OS switches between programs to keep the CPU busy during I/O waits.
Improves CPU utilization and system efficiency.
What is time-sharing in an operating system?
CPU time is shared between users, so it feels like everything runs at once
The CPU is shared between users via time slices, enabling fast switching.
Users experience the system as responsive and concurrent.
What is process management in an operating system?
Managing how processes start, run, and stop
Involves creation, scheduling, and termination of processes.
Ensures fairness, efficiency, and isolation among processes.
What are the five states of a process in an OS?
New – Process is being created.
Ready – Process is waiting for CPU time.
Running – Process is being executed.
Waiting (Blocked) – Process is waiting for some resource, like I/O.
Terminated – Process has finished and is no longer running.
OS moves processes between these states based on execution and I/O needs.
What is a Process Control Block (PCB)?
Stores process info like state, program counter, and memory details
Contains process ID, state, registers, memory limits, scheduling info, etc.
Used during context switching and process management.
What is context switching in an OS?
Saving the state of a running process and loading the state of another
Involves storing the PCB of the current process and loading the PCB of the next.
Enables multitasking, but adds overhead.
What is the goal of CPU scheduling?
Choosing which processes to run to make the CPU and system work efficiently
Aims to maximize CPU utilization and throughput, and minimize waiting and response time.
Name three common CPU scheduling algorithms.
First Come, First Served (FCFS)
Shortest Job First (SJF)
Round Robin (RR)
What is the main drawback of FCFS scheduling?
It can lead to the convoy effect, where short tasks wait for long ones to finish
What is the advantage of SJF scheduling?
It reduces average wait time, but guessing the next CPU burst is hard
What is the key feature of Round Robin scheduling?
Each process gets a set time to run, improving how quickly the system responds
How does priority scheduling work?
Processes run based on priority, with higher-priority ones going first.
Can cause starvation if low-priority processes are indefinitely postponed.
What is a deadlock in an operating system?
A situation where processes are stuck waiting for each other to release resources
System becomes stuck unless external intervention occurs
How can deadlocks be prevented?
By making sure one of the key conditions for deadlock doesn’t happen
Prevents system-wide halt but may reduce efficiency.
What is the primary goal of memory management?
To manage and use the computer’s main memory efficiently
Includes tasks like paging, segmentation, swapping, and protection.
What is paging in memory management?
Memory is split into fixed-size pages to reduce fragmentation
OS maps pages to frames via page tables, avoiding fragmentation.
Efficient memory use; causes overhead in managing page tables.
What is virtual memory?
Uses disk space to make it seem like there’s more memory than actually available.
Inactive pages are swapped to disk (page file), allowing larger or more programs to run.
Enables multitasking; slower than RAM, may cause thrashing.
What is I/O management in an OS?
Controls devices and handles data transfer between them and the CPU
Handles buffering, caching, scheduling, and error handling for I/O.
