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Computer Science IGCSEPDF 49
142 pagesrevision 46930
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● Single-User, Single-Tasking (MS-DOS)
● Single-User, Multitasking (Windows 11, macOS)
● Multi-User (UNIX)
● Real-Time OS (RTOS): Used in robotics, aircraft control.
● Distributed OS: Manages multiple networked systems.
● Embedded OS: Compact, efficient systems (ATMs, washing machines).
When powered on, the BIOS (Basic Input/Output System), stored in ROM, performs a POST
(Power-On Self-Test). The BIOS then loads the Bootstrap Loader, which locates and loads the
OS kernel into RAM. The OS initializes hardware and starts background processes.
C. Types of Operating Systems
Input/Output and Peripheral Management: Manages communication between CPU
and devices (keyboard, printer, drives) via device drivers.
File Management: Handles creation, naming, storage, retrieval, and deletion of files.
User Interface (HCI): Provides interaction between user and system.
○ GUI (Graphical User Interface): Uses windows, icons, menus, and pointers
(WIMP).
○ CLI (Command Line Interface): Text-based, requires command knowledge, less
memory-intensive.
Security Management: Controls authentication, passwords, and access rights.
Interrupt Handling: Responds to signals requesting CPU attention.
Error Handling: Detects and resolves hardware/software faults.
B. The Boot-Up Process
4.3 Utility Software