OPERATING SYSTEMS
Exam Power Notes • Quick Revision Guide
Description: Concise exam-focused notes covering processes, threads, CPU scheduling,
memory management, deadlocks, file systems, system calls, Q&A and MCQs.
Keywords: Operating Systems, OS Notes, OS Exam, Process Management, CPU Scheduling,
Memory Management, Deadlock, Paging, Virtual Memory, File System, Threads, Exam Preparation
1. What is an Operating System?
An Operating System (OS) is system software that manages computer hardware and
provides services and an environment for application programs.
Main responsibilities: process management, memory management, file management,
device management, security and resource allocation.
2. Process & Program
A program is a passive set of instructions. A process is a program in execution.
Common process states: New, Ready, Running, Waiting/Blocked, Terminated.
3. Threads
A thread is a unit of execution within a process. Threads can share process resources
while maintaining their own execution state.
4. CPU Scheduling
CPU scheduling selects a ready process for CPU execution.
FCFS = First-Come, First-Served; SJF = Shortest Job First;
Priority Scheduling selects according to priority; Round Robin uses a time quantum.
5. Memory Management
Paging divides logical memory into fixed-size pages and physical memory into frames.
Virtual memory allows programs to use an address space larger than physical RAM.
Exam Power Notes • Quick Revision Guide
Description: Concise exam-focused notes covering processes, threads, CPU scheduling,
memory management, deadlocks, file systems, system calls, Q&A and MCQs.
Keywords: Operating Systems, OS Notes, OS Exam, Process Management, CPU Scheduling,
Memory Management, Deadlock, Paging, Virtual Memory, File System, Threads, Exam Preparation
1. What is an Operating System?
An Operating System (OS) is system software that manages computer hardware and
provides services and an environment for application programs.
Main responsibilities: process management, memory management, file management,
device management, security and resource allocation.
2. Process & Program
A program is a passive set of instructions. A process is a program in execution.
Common process states: New, Ready, Running, Waiting/Blocked, Terminated.
3. Threads
A thread is a unit of execution within a process. Threads can share process resources
while maintaining their own execution state.
4. CPU Scheduling
CPU scheduling selects a ready process for CPU execution.
FCFS = First-Come, First-Served; SJF = Shortest Job First;
Priority Scheduling selects according to priority; Round Robin uses a time quantum.
5. Memory Management
Paging divides logical memory into fixed-size pages and physical memory into frames.
Virtual memory allows programs to use an address space larger than physical RAM.
