Operating Systems

Week of 2026-09-08 · Download .docx

Objectives

Configure and troubleshoot Windows using built-in tools including Task Manager, Event Viewer, Device Manager, msconfig, and sfc /scannow.
Use Linux command-line tools to navigate, manage files, set permissions with chmod, and install software with apt.
Compare file systems (NTFS, FAT32, exFAT, ext4) and partition tables (MBR vs. GPT) and select the appropriate format for common scenarios.
Explain OS process management, virtual memory, and the impact of page file usage on system performance.

Key terms

Operating System: Software layer between hardware and user applications that manages CPU scheduling, memory, file systems, I/O devices, and security.
Task Manager: Windows utility (Ctrl+Shift+Esc) showing live CPU, memory, disk, and network usage alongside per-process resource consumption.
Event Viewer: Windows logging tool (eventvwr.msc) recording System, Application, and Security events — the first diagnostic step after a crash or service failure.
NTFS: New Technology File System — Windows default file system supporting ACL permissions, EFS encryption, journaling, and files exceeding 4 GB.
FAT32: File Allocation Table (32-bit) — legacy file system limited to 4 GB per file and no permission or encryption support; used for compatibility.
exFAT: Extended FAT — cross-platform file system for removable media (USB, SD card) supporting files over 4 GB, natively readable by Windows and macOS.
GPT: GUID Partition Table — modern partition standard supporting drives over 2 TB and up to 128 partitions; required for UEFI boot.
Virtual Memory: OS technique using a page file (Windows) or swap space (Linux) on disk as overflow when physical RAM is exhausted.
Page File: Reserved disk area Windows uses as virtual RAM overflow when physical RAM is full. Access is 100–1,000× slower than RAM.
Zombie Process: A terminated process whose entry remains in the process table because the parent process has not read its exit status. Consumes no CPU but occupies a PID.
Daemon: A background system service process (Linux/macOS) that runs continuously without user interaction — examples: sshd, httpd, crond.
chmod: Linux command to change file permission bits (read/write/execute) for owner, group, and others using symbolic or numeric (octal) notation.
sfc /scannow: Windows System File Checker command that scans and automatically replaces corrupted or missing protected system files.

The concept

Operating systems are the invisible managers that coordinate all hardware and software activity. Without an OS, there is no practical way for a user or application to interact with hardware.

**What the OS Does**

The OS provides four critical services: (1) CPU scheduling — allocating processing time across multiple running processes; (2) memory management — tracking which RAM addresses each process uses and managing the page file; (3) file system management — organizing data into files and directories on storage devices; (4) device management — loading the correct drivers so the OS can communicate with hardware.

**Windows Administration**

Windows professionals work with several essential utilities. Task Manager (Ctrl+Shift+Esc) shows live performance data and can kill unresponsive processes. Event Viewer records all significant system events — it is the first tool to open after a Blue Screen of Death or mysterious service failure. Device Manager shows all installed hardware with driver status — a yellow exclamation mark indicates a driver problem. msconfig (System Configuration) controls startup programs and boot options including Safe Mode. The command sfc /scannow scans and repairs corrupted Windows system files.

Safe Mode starts Windows with only essential drivers and no third-party software — invaluable for diagnosing driver conflicts and removing malware that would otherwise hide in normal mode.

**Linux Command Line**

Linux is administered primarily through the command line. Essential commands: ls (list directory contents), cd (change directory), pwd (print working directory), chmod (change permissions), and apt (install/remove software on Debian/Ubuntu).

Linux permissions use three triplets: owner/group/others. Each triplet has read (r=4), write (w=2), and execute (x=1) bits. Numeric representation 755 means rwxr-xr-x — owner has full permissions, group and others have read+execute only.

**File Systems and Partitions**

Different file systems serve different purposes. NTFS is Windows' primary file system with ACL permissions, journaling, and no practical size limits. FAT32 is a legacy cross-platform format limited to 4 GB per file. exFAT is the modern cross-platform format for USB drives, removing FAT32's 4 GB limit. ext4 is Linux's standard file system.

GPT (GUID Partition Table) replaced the older MBR format to support drives over 2 TB and is required for UEFI boot. MBR is limited to 2 TB and 4 primary partitions.

**Process Management and Virtual Memory**

The OS scheduler continuously allocates CPU time slices to runnable processes. When all physical RAM is consumed, the OS creates a page file (Windows) or swap space (Linux) on the hard drive to extend addressable memory. Accessing the page file is 100–1,000× slower than RAM, causing the severe performance degradation called thrashing. Adding physical RAM is the most direct remedy.

Worked examples

Example 1: Troubleshooting a Windows system freeze: A student's laptop freezes after installing new software. Step 1: Boot into Safe Mode (msconfig → Boot → Safe boot) to determine if the issue is driver/startup-related. Step 2: If stable in Safe Mode, open Event Viewer → Windows Logs → System to find error events logged at the time of the freeze. Step 3: Open Device Manager to check for yellow exclamation marks indicating driver failures. Step 4: Run sfc /scannow from an elevated command prompt to rule out corrupted system files. Each step narrows the root cause systematically.

Example 2: Linux permission calculation: A script file shows permissions -rwxr-xr--. Calculate the numeric value: owner r(4)+w(2)+x(1)=7; group r(4)+x(1)=5; others r(4)=4. Numeric: 754. To make the file executable by everyone, run: chmod 755 filename (adds execute for group). To make it readable only by the owner, run: chmod 400 filename. The command chmod +x filename adds execute permission for all using symbolic notation.

Common mistakes

Using Task Manager when Event Viewer is needed. Task Manager shows current state; Event Viewer shows historical events that caused the problem. Crashes and service failures leave log entries in Event Viewer that Task Manager cannot reveal.
Formatting a 64 GB USB drive as FAT32. FAT32's 4 GB per-file limit means you cannot copy any file larger than 4 GB — including modern game installs and video files. Use exFAT for cross-platform removable media.
Thinking a 64-bit OS runs faster than a 32-bit OS. The difference is address space — a 64-bit OS can address more than 4 GB of RAM, which allows memory-intensive applications to run without hitting the 32-bit ceiling. Raw computation speed depends on architecture, not bit-width alone.
Confusing Safe Mode with a factory reset. Safe Mode starts Windows with minimal drivers and is fully reversible — it is a diagnostic tool. A factory reset deletes user data and reinstalls the OS. Safe Mode is always the first diagnostic step.
Misreading Linux permission strings. In rwxr-xr-x, the first character (- or d) indicates file vs. directory. The next nine characters are three triplets of rwx for owner, group, and others. Position 4 (the first character of group permissions) is the start of the group triplet, not a continuation of owner permissions.

Self-check

Try each question before reading the answer. Answers at the bottom of this page.

1. Which Windows tool shows historical error events logged during a system crash?

Task Manager
Event Viewer
msconfig
Device Manager

2. What is the maximum individual file size on a FAT32-formatted drive?

2 TB
4 GB
16 TB
Unlimited

3. What does the Linux command chmod 755 set?

Read-only for all users
Full permissions for owner; read+execute for group and others
Full permissions for everyone
No permissions for anyone

4. When Windows RAM is exhausted, the OS uses:

CPU cache as overflow
GPU VRAM as extra RAM
A page file on disk
ROM for temporary storage

5. GPT is required instead of MBR when:

The drive is less than 500 GB
The system uses UEFI firmware and/or the drive exceeds 2 TB
The OS is Windows 7 or older
The drive uses the exFAT file system

Self-check answers

1. B — Event Viewer records all significant system events including crashes, service failures, and security audit entries.
2. B — FAT32 uses 32-bit cluster addresses, limiting individual files to exactly 4 GB minus 1 byte.
3. B — 755 = rwxr-xr-x: owner has read(4)+write(2)+execute(1)=7; group and others have read(4)+execute(1)=5.
4. C — The OS creates a page file on disk as a RAM overflow area. Disk access is 100–1,000× slower than RAM, causing performance degradation.
5. B — GPT supports drives over 2 TB and is required for UEFI boot. MBR is limited to 2 TB and 4 primary partitions.

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