Operating Systems

Week of 2026-09-01 · Download .docx

Objectives

Compare file system types including NTFS, FAT32, exFAT, and ext4 and explain their use cases.
Explain process and memory management concepts including virtual memory and thrashing.
Describe Unix/Linux fundamentals including file permissions and common shell commands.
Use Windows administration tools including Task Manager, Event Viewer, and regedit.

Key terms

NTFS: New Technology File System — Windows default; supports permissions, encryption, journaling, large files.
FAT32: Older file system with 4 GB maximum file size; widely compatible with all devices.
exFAT: Extended FAT — cross-platform flash drive format; no 4 GB file limit.
ext4: Fourth Extended File System — the standard Linux file system with journaling.
Journaling: File system feature that logs pending changes so they can be replayed after a crash.
Virtual memory: Disk space used as overflow RAM when physical RAM is exhausted; stored in pagefile.sys.
Thrashing: Severe performance collapse when the OS spends more time swapping pages than running programs.
GPT: GUID Partition Table — modern disk partition standard; supports >2 TB drives and UEFI boot.
Safe Mode: Windows diagnostic boot that loads only essential drivers, no third-party software.
chmod: Linux command that changes file and directory read/write/execute permissions.
apt: Advanced Package Tool — Debian/Ubuntu package manager for installing software.
Event Viewer: Windows tool that displays logged system, application, and security events.
regedit: Windows Registry Editor — provides direct access to the OS configuration database.
WOW64: Windows on Windows 64 — subsystem allowing 32-bit apps to run on 64-bit Windows.
msconfig: Windows System Configuration utility for managing startup programs and boot options.

The concept

The operating system (OS) is the software layer between hardware and user applications. It manages the CPU scheduler, memory allocator, file system, device drivers, and user interface. Every running program is a process — an isolated instance with its own virtual memory space. Within a process, threads share memory and are the smallest units the CPU scheduler dispatches.

Virtual memory allows the OS to support more processes than RAM alone could hold. When physical RAM fills, the OS moves inactive pages to a reserved disk area (pagefile.sys on Windows, swap on Linux). This works quietly until RAM is severely over-committed, causing thrashing — the disk I/O rate saturates and CPU spends all its time swapping rather than executing useful code. The cure is more RAM or closing programs.

File systems define how data is organized on a disk. NTFS is the Windows standard — it supports per-file permissions (ACLs), journaling to survive power loss, and files as large as 16 TB. FAT32 is universally readable but limited to 4 GB per file. exFAT removes that limit and is natively read/write on both Windows and macOS, making it the right format for shared flash drives. ext4 is Linux's default, offering journaling, extents, and backward compatibility.

Disk partitioning uses either MBR or GPT. GPT supports drives larger than 2 TB, up to 128 primary partitions, and is required for modern UEFI boot. A Full Format writes zeros and scans for bad sectors; Quick Format only reinitializes the file table without surface scanning.

Windows administration relies on a toolkit of built-in utilities. Task Manager shows real-time process CPU and RAM use and lets you end unresponsive programs. Event Viewer categorizes log entries by System, Application, and Security, with timestamps and error codes that identify crash causes. msconfig controls startup programs and boot options including Safe Mode entry. regedit provides raw access to the registry hive for advanced configuration. 64-bit Windows uses WOW64 to execute 32-bit applications transparently, but 16-bit applications are not supported at all on 64-bit Windows.

Linux file permissions use a nine-character string: three groups of rwx representing the owner, group, and others. The chmod command changes these bits. Linux package managers (apt for Debian/Ubuntu, dnf for Fedora) download, install, and resolve dependencies from curated repositories — eliminating the need to hunt for installer files.

Worked examples

Example 1: A student copies a 6 GB video file to a flash drive formatted as FAT32 and gets an error. You explain that FAT32 enforces a 4 GB per-file maximum. You reformat the drive as exFAT using Windows' Disk Management tool and confirm the copy succeeds. exFAT is natively readable on the MacBook the student also needs to use.

Example 2: A Windows laptop feels extremely slow. Task Manager shows CPU at 5% but disk at 100%. You check: the system has 4 GB RAM and 12 browser tabs plus several apps open. RAM is at 95%, forcing constant paging — thrashing. You identify that closing unused browser tabs drops disk activity immediately. Long term, adding RAM is the correct fix.

Common mistakes

Using FAT32 for drives that need to store files larger than 4 GB — always use exFAT or NTFS instead.
Opening regedit and editing keys without knowing what they do — a corrupt registry can prevent Windows from booting.
Confusing rwx permission triplets — remember: owner | group | others, each with read/write/execute in that order.
Assuming Safe Mode with Networking is the same as Safe Mode — only the Networking variant has internet access.
Skipping the pre-change snapshot before editing startup programs or the registry — always create a restore point first.

Self-check

Try each one before you look. A miss here costs nothing and tells you exactly what to reread.

1. Which file system is the correct choice for a flash drive used on both Windows and macOS with files larger than 4 GB?

2. What does thrashing indicate?

3. Which permission string means the owner has full access and everyone else has read-only?

4. Which Windows tool displays historical logged error events for diagnosing crashes?

5. A GPT partition table is required for which feature?

Canvas is the official record. This companion enhances the PGCC curriculum; it does not replace it. Last name and class year only. Students with a 504 plan or IEP: your accommodations apply.

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