--- title: "What is an OS; its functions" subject: "Operating System" chapter: 1 key: "semester_6/operating_system:os-functions-definition" source: https://www.bctengineer.com/q/semester_6/operating_system/os-functions-definition site: BCT Engineering --- # What is an OS; its functions Operating System · Chapter 1: Introduction to Operating System - Asked in: 2075 Baisakh, 4 marks; 2072 Asoj, 1+4 marks (asked 2 times) - Video: [What is an Operating System? Goals & Functions of Operating System | Concept Simplified by Animation](https://www.youtube.com/watch?v=ACsLvXuaKxw) — making IT simple - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/operating_system/os-functions-definition - Whole chapter: https://www.bctengineer.com/md/semester_6/operating_system/chapter-1 ## Question What is an operating system? Explain the functions of an operating system. ## Short answer An operating system is system software that manages computer hardware and provides an environment for users and applications. Its functions include process management, memory management, file management, device management, secondary storage management, protection and security, user interface, error handling, resource allocation, and networking. ## Answer An **operating system (OS)** is system software that manages the computer hardware and provides a convenient, efficient environment in which users and application programs can run. It acts as an interface between the user and the hardware and as the manager of all resources (CPU, memory, files, I/O devices). #### Functions of an operating system 1. **Process management**: creates and deletes processes, schedules the CPU, suspends and resumes processes, and provides process synchronization and communication. 2. **Memory management**: keeps track of which memory parts are in use and by whom, allocates and de-allocates memory, and handles swapping and virtual memory. 3. **File management**: creates, deletes, reads, writes and protects files and directories, and maps files onto secondary storage. 4. **Device (I/O) management**: hides hardware details through device drivers, buffering, caching and spooling, and schedules I/O requests. 5. **Secondary-storage management**: free-space management, disk allocation and disk scheduling. 6. **Protection and security**: controls access of programs and users to resources, authenticates users and guards against unauthorised use. 7. **User interface / command interpretation**: provides a shell (CLI) or a GUI so the user can give commands. 8. **Error detection and handling**: detects errors in the CPU, memory, I/O devices or user programs and takes suitable action. 9. **Resource allocation and accounting**: decides who gets which resource and records usage for billing and statistics. 10. **Networking**: lets machines communicate and share resources. Overall, the OS works as an **extended machine** (it hides the ugly hardware and gives simple abstractions such as files and processes) and as a **resource manager** (it shares the hardware fairly and safely among competing programs). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which statement best defines an operating system? A. System software that manages hardware resources and gives users and programs a convenient environment B. An application that only provides a graphical desktop C. Hardware that connects the CPU to memory and I/O D. A compiler that translates programs into machine code Answer: A. The OS is system software that acts as an interface between user and hardware and manages all resources. (Key point: Definition of OS) 2. Which task belongs to memory management? A. Scheduling disk head movement B. Keeping track of which memory parts are in use and by whom, and allocating and freeing them C. Authenticating users at login D. Creating and deleting directories Answer: B. Memory management tracks usage, allocates/de-allocates memory and handles swapping and virtual memory. (Key point: Memory management) 3. How does the OS hide hardware details of I/O devices from programs? A. By compiling every program for each device B. By giving each program direct access to controller registers C. Through device drivers, buffering, caching and spooling D. By storing all data in main memory only Answer: C. Device management uses drivers, buffering, caching and spooling and schedules I/O requests. (Key point: Device management) 4. In which two roles does the OS work overall? A. Compiler and linker B. Editor and debugger C. Assembler and loader D. Extended machine and resource manager Answer: D. It hides ugly hardware behind abstractions (extended machine) and shares resources fairly and safely (resource manager). (Key point: Dual role of OS) ## Related in Operating System - [OS abstraction, extended machine, system call](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Aos-abstraction-system-call) — Operating System, chapter 1 - [Functions of OS and microkernel](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Aos-functions-microkernel) — Operating System, chapter 1 - [OS as virtual machine; functions](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Aos-virtual-machine-functions) — Operating System, chapter 1 - [OS definition and types of OS](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Aos-definition-types) — Operating System, chapter 1 - [Layered vs monolithic OS structure](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Alayered-vs-monolithic) — Operating System, chapter 1 - [Pipe, shell; OS as resource manager](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Apipe-shell-resource-manager) — Operating System, chapter 1 ## Related in other subjects - [Features of a typical operating system](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Afeatures-of-operating-system) — Microprocessor, chapter 6, asked 3× - [Operating system layers](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Aos-layers) — Distributed System, chapter 3 - [Real-time system and real-time OS components](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Areal-time-os) — Software Engineering, chapter 4 - [Digital switching system and its functions](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Adigital-switching-functions) — Telecommunications, chapter 4