Unit 05
⚙️ System Software
Computer Operating
Systems
The Operating System is the invisible backbone of every computer — managing processes, memory, files and devices so applications can run. Explore how modern OSes evolved, how they schedule and control processes using state diagrams, how they organise files and storage, and how they manage physical and virtual memory. Covers competency levels 5.1–5.4 from the NIE ICT syllabus.
🖥️ Definition & Evolution of OS
🔧 Main Functions of OS
📂 OS Classification Types
📁 File Types & Attributes
🗂️ Directory & File Systems
🔐 File Security & Passwords
💾 Storage Allocation Methods
🔄 Disk Defragmentation
⚡ Process Definition
🔁 Process States (7-State)
📋 Process Control Block
🔀 Context Switching
📅 Process Schedulers
🧠 Memory Management (MMU)
🌐 Virtual Memory & Paging
🖨️ Device Drivers & Spooling
📚 Competency Levels — Unit 05
COMPETENCY 5.1 · 4 PERIODS
Introduction to OS
Definition, evolution, and main functions: providing interfaces, process management, resource management, security. Classification: single/multi user, multi-task, multi-threading, real-time, time-sharing.
COMPETENCY 5.2 · 6 PERIODS
File & Directory Management
File types and attributes, file hierarchy and FAT file systems, file security via passwords and access privileges. Storage allocation: contiguous, linked and indexed. Defragmentation and disk formatting.
COMPETENCY 5.3 · 6 PERIODS
Process Management
Process definition, interrupts and interrupt handling, process states and transitions (7-state diagram), process control block (PCB), context switching. Long, short and medium-term schedulers. Multiprogramming vs. time-sharing. Turnaround, response, throughput and waiting time.
COMPETENCY 5.4 · 6 PERIODS
Resource Management
Memory Management Unit (MMU), physical and virtual memory, paging and mapping. I/O device management: device drivers and spooling. Installing appropriate device drivers when connecting peripherals.
⚡ Process State Transition — Quick Reference
New
Admitted
──▶
Ready
Dispatcher
──▶
Running
I/O or Event
──▶
Waiting
I/O Complete
──▶
Terminated
New → Ready: process admitted by OS
Ready → Running: CPU assigned by dispatcher
Running → Ready: preempted / time slice expired
Running → Waiting: waiting for I/O or event
Waiting → Ready: I/O or event completed
Running → Terminated: process finishes execution
📊 OS Classification — Quick Reference
| OS Type | Description | Example |
|---|---|---|
| Single User — Single Task | One user, one program at a time | MS-DOS |
| Single User — Multi Task | One user, multiple programs simultaneously | Windows, macOS |
| Multi User — Multi Task | Multiple users and programs at same time | Linux, UNIX |
| Multi-Threading | Multiple threads of a process run concurrently | Windows, Linux |
| Real-Time OS (RTOS) | Guaranteed response within strict time constraints | VxWorks, FreeRTOS |
| Time Sharing | CPU time divided among users/processes rapidly | UNIX time-sharing |
📥 Unit 05 — Available Downloads
📄
Full Notes — Operating Systems
PDF · 4.3 MB · 60 pages
📄
Operating Systems - Note
PDF · 0.9 MB · 8 pages
📄
File Systems
PDF · 1.1 MB · 12 pages
📄
(Operating Systems) Process Management
PDF · 1.0 MB · 10 pages
📄
Operating Systems - Short Notes
PDF · 0.8 MB · 8 pages
📊
Slide Deck — Operating Systems
PPTX · 5.9 MB · 46 slides
📄
Revision Summary Card
PDF · 0.5 MB · 2 pages