Operating System Types, Filesystems, Life Cycles, and Compatibility
Unit 1: Operating Systems and Installation. Lesson 1 of 41 in APlus Academy Core 2.
Core 2 opens with the map: which operating systems exist, which filesystems they use, and why a file or program from one may not work on another. These are recall questions with a few rules behind them.
Workstation operating systems
- Windows: the business desktop standard. Editions from Home to Enterprise, NTFS drives, domain or workgroup membership, and the tools this course spends four units on.
- Linux: an open-source kernel packaged into distributions. Ubuntu and Debian install software with apt; Fedora and Red Hat use dnf. Case-sensitive filesystems, a root superuser, and administration from the command line.
- macOS: Apple's desktop OS, only on Apple hardware, built on a Unix core with the APFS filesystem, the App Store, Time Machine backups, and FileVault encryption.
- Chrome OS: Google's browser-centered system on Chromebooks; apps are web apps and Android apps, data lives in the cloud, and management is through the Google Admin console. Cheap to buy and to manage, poor for heavy local software.
Mobile operating systems
- iOS on iPhones and iPadOS on iPads: closed platform, one app store, updates pushed to every supported device at once; sideloading needs enterprise profiles.
- Android: Google's open platform used by many manufacturers; alternative app sources are possible, which raises the malware risk, and updates arrive at different times per vendor.
Filesystems
A filesystem is how an OS organizes a disk. Choose one by what has to read the disk.
- NTFS: Windows system and data drives. Permissions per file and folder, encryption (EFS), compression, journaling (survives crashes), volumes and files far beyond terabytes.
- ReFS (Resilient File System): Windows Server and Pro for Workstations. Integrity checking and self-repair for huge data volumes; not a boot filesystem for ordinary editions.
- FAT32: the old universal format. Any device reads it, but a single file cannot exceed 4 GB, and Windows formats it only up to 32 GB.
- exFAT: FAT without the 4 GB limit; the right choice for a large flash drive or SD card that must move between Windows, macOS, and Linux. No permissions, no journaling.
- ext4: the default on most Linux distributions; journaling, large files; Windows cannot read it natively.
- XFS: a Linux filesystem for very large files and volumes; the default on Red Hat.
- APFS (Apple File System): macOS and iOS; snapshots, built-in encryption, instant cloning, tuned for SSDs; replaced HFS+.
Vendor life cycles
Every OS version has a product life cycle ending at end-of-life (EOL), after which no security updates ship. Running an EOL system is a vulnerability the security domain names by that word. Update limitations also exist inside the life cycle: an old CPU or a missing TPM blocks an upgrade, a Home edition lacks features an update needs, and vendors stop supporting older phones long before they stop working. Windows 10 reached end of support in October 2025.
The exam calls these vendor life-cycle limitations: an operating system past end-of-life, or one that no longer receives updates on that hardware, is a limitation the technician must plan around.
Compatibility concerns
- Programs and drivers are built for a specific OS and architecture; 64-bit Windows runs 32-bit programs, but a 32-bit OS cannot run 64-bit programs, and no Windows program runs on macOS without a compatibility layer or a virtual machine.
- Files cross between systems only on a filesystem both can read: exFAT or FAT32 for a shared drive, or a network share, or the cloud.
- Document formats, line endings, and case sensitivity (Linux treats File.txt and file.txt as different) trip up mixed environments.
- Hardware needs a driver for the OS in use; an old printer may have a Windows driver and no macOS driver.
Compatibility concerns between operating systems come up whenever files, applications, or drives move between Windows, macOS, and Linux.
Operating System Types, Filesystems, Life Cycles, and Compatibility, explained slowly
Operating systems as languages
Think of each operating system as a language and each filesystem as an alphabet. A program is written in one language; a disk is written in one alphabet. Windows speaks Windows and reads NTFS, FAT32, and exFAT. Linux speaks Linux and reads ext4, XFS, and the FAT family, and can be taught NTFS. macOS speaks macOS and reads APFS, HFS+, FAT32, and exFAT, and can read NTFS but not write it without help. Compatibility questions are always "does this side speak that language or read that alphabet?"
Where each OS lives
OS hardware strengths management Windows any PC business software, games, domains Active Directory, Group Policy, Intune Linux any PC, servers, embedded free, servers, developers, appliances command line, configuration management macOS Apple Macs only design, media, Apple ecosystem Apple Business Manager, MDM Chrome OS Chromebooks cheap, simple, cloud-first, schools Google Admin console iOS/iPadOS iPhone, iPad closed, consistent updates MDM, Apple Business Manager Android many phone and tablet makers open, flexible, sideloading possible MDM; updates vary by maker
Filesystems, what to pick
filesystem made for file size limit permissions journaling read by NTFS Windows huge yes yes Windows; macOS read-only; Linux with drivers ReFS Windows Server, Pro for Workstations huge yes integrity streams Windows only FAT32 universal, old 4 GB no no everything exFAT big removable media huge no no Windows, macOS, Linux, cameras, consoles ext4 Linux huge yes yes Linux XFS Linux, big data huge yes yes Linux APFS Apple huge yes copy-on-write macOS, iOS
Decision rules: formatting a USB stick that will move between a Mac and a PC with video files over 4 GB means exFAT; a Windows system drive means NTFS; a camera card usually wants FAT32 or exFAT per the camera; a Linux root means ext4 (or XFS on Red Hat).
Life cycles, drawn
release --- mainstream support (features and fixes) --- extended support (security only) --- end of life (nothing) Windows 10: released 2015, ended October 2025. Phones: typically 3 to 7 years of updates depending on the maker.
"Update limitations" are the reasons a device stops getting the next version before EOL: the CPU is not on the list, there is no TPM, the storage is too small, the edition does not qualify, or the vendor decided the model is done. The security domain calls an EOL system a vulnerability and the answer is replacement or isolation.
Compatibility, worked
- A user brings a Linux-formatted external drive to a Windows PC: nothing appears in File Explorer, and Disk Management shows a healthy partition with no letter and an unknown filesystem. Windows cannot read ext4. Reformat to exFAT (after copying the data on a Linux machine), or install a third-party ext4 driver.
- A company buys 64-bit-only accounting software, and three old machines run 32-bit Windows 10. The software will not install. Those machines need a clean install of 64-bit Windows (if the CPU supports it) or replacement; a 32-bit OS cannot run 64-bit programs.
- A designer's macOS application has no Windows version. Options: a virtual machine running macOS is not licensed on non-Apple hardware, so the answer is a Mac, a web version, or an equivalent Windows application.
- A file named Report.TXT and report.txt coexist on a Linux server; a Windows client sees one overwrite the other. Case sensitivity differs; rename.
How the exam asks it
- "Which filesystem should a technician use for a 64 GB flash drive that must hold 8 GB files and work on Windows and macOS?" exFAT.
- "Which filesystem supports file permissions and encryption on Windows?" NTFS.
- "Which OS is designed around a browser and cloud storage?" Chrome OS.
- "A system that no longer receives security patches is described as?" End-of-life.
- "Which Linux filesystem is the default on most distributions?" ext4.
- "Which Apple filesystem replaced HFS+?" APFS.
What to memorize
- The OS table: who makes it, where it runs, apt versus dnf, App Store, Admin console.
- The filesystem table, especially FAT32's 4 GB limit, exFAT for cross-platform media, NTFS features, ReFS resilience, APFS for Apple.
- EOL and update limitations. 64-bit runs 32-bit, not the reverse. Shared media needs a shared filesystem.