Unit 3 — 5-minute revision
- OS functions (6): process management, memory management, file management, device management, security, user interface
- OS types: batch, time-sharing, real-time, distributed, multiprogramming, multitasking
- Single-user: one user at a time (MS-DOS, Windows); Multi-user: many users together (UNIX, Linux)
- Real-time OS: fixed deadlines — railway reservation, air traffic control; Distributed OS: many machines act as one
- Windows: GUI-based, Microsoft, user-friendly, single/multi-user versions; Linux: open source, Linus Torvalds (1991), multi-user, secure, kernel + shell
- Kernel: core of OS, manages hardware; Shell: interface between user and kernel
- Booting: loading OS into RAM at startup — cold boot (power on), warm boot (restart)
- File system: organizes data on disk — FAT, NTFS (Windows), ext4 (Linux)
🔥 High-yield: Linux = open source, Linus Torvalds 1991; kernel = core of OS; single-user = MS-DOS, multi-user = UNIX/Linux; cold boot = switch on, warm boot = restart.
| Term | Full form |
|---|---|
| OS | Operating System |
| BIOS | Basic Input Output System |
| POST | Power On Self Test |
| FAT | File Allocation Table |
| NTFS | New Technology File System |
| MS-DOS | Microsoft Disk Operating System |
| GUI | Graphical User Interface |
| CUI | Character User Interface |
