Operating Systems · Topic 1 of 15
Operating System Types and File Systems
Compare Windows, macOS, Linux, ChromeOS and mobile operating systems, their file systems, and the limits that end of life and compatibility create.
- 5 min
- Windows, macOS, iOS and iPadOS are proprietary. Linux is open source.
- NTFS is the Windows file system and supports permissions and encryption.
- FAT32 limits a single file to 4 GB. exFAT removes that limit for removable drives.
What it is
An operating system (OS) is the software that manages the hardware, runs applications and gives the user an interface. A technician must recognise the main families, know which file system each one uses, and understand when an OS is too old to support.
How it works
Each OS is built for a purpose, a hardware platform and a licensing model.
The main families
| OS | Typical use | Licensing | Notes |
|---|---|---|---|
| Windows | Business and home desktops, laptops, servers | Proprietary (Microsoft) | Largest application and driver support |
| macOS | Apple desktops and laptops | Proprietary (Apple) | Runs on Apple hardware only |
| Linux | Servers, developer machines, embedded devices | Open source | Many versions called distributions (distros), such as Ubuntu and Fedora |
| ChromeOS | Low cost laptops, schools | Proprietary, built on open source parts | Browser centred, apps are web or Android based |
| iOS and iPadOS | iPhone and iPad | Proprietary (Apple) | Apps come mainly from the App Store |
| Android | Phones, tablets and many other devices | Based on open source code | Vendors add their own changes |
A proprietary OS is owned and licensed by one company. An open source OS publishes its source code, so anyone may study it, change it and share it under the licence terms.
Workstation and mobile roles
A workstation OS is used on desktops and laptops for office work, development and design. A mobile OS is designed for touch screens, battery life, cellular and wireless radios, and app stores. A server OS is tuned to provide services to many clients, though the exam focuses on client systems.
File systems
A file system decides how data is stored on a drive, and it limits file sizes, security features and compatibility.
| File system | Used by | Key points |
|---|---|---|
| NTFS (New Technology File System) | Windows | Permissions, encryption, compression, journaling, very large files |
| FAT32 (File Allocation Table 32) | Old drives, small flash drives | Works almost everywhere, but a single file cannot exceed 4 GB |
| exFAT (extended FAT) | Flash drives, memory cards | Large files, works on Windows and macOS, no permissions |
| ext4 (fourth extended file system) | Linux | Journaling, common Linux default |
| APFS (Apple File System) | Current macOS, iOS, iPadOS | Built for flash storage, supports encryption and snapshots |
| HFS+ (Hierarchical File System Plus) | Older macOS | Replaced by APFS |
| CDFS (Compact Disc File System) | Optical discs | Read only disc format |
A journaling file system records changes before it applies them, so it recovers more cleanly after a crash.
Two more file systems appear in server settings. ReFS (Resilient File System) is a Microsoft file system for Windows Server and Pro for Workstations. It is built to detect and repair corruption and to handle very large volumes, but client Windows does not use it as the boot drive.
XFS is a high performance journaling file system for Linux. It is common on Red Hat family servers.
Architecture
A 32 bit OS can address only about 4 GB of memory, while a 64 bit OS can use far more. A 64 bit OS can usually run 32 bit applications, but a 32 bit OS cannot run 64 bit applications. Some devices use ARM (Advanced RISC Machine) processors instead of x86 processors, and software generally has to be built for the processor type, or run through an emulation layer.
Vendor life cycle limitations
Every OS version has a support life cycle. When it reaches end of life (EOL), the vendor stops issuing security patches and fixes. Running an EOL system is a security risk and often blocks support from software vendors.
Update limitations also apply. A device can lose updates when its hardware is too old, as with many phones that stop receiving new Android or iOS versions. In a business, an EOL OS may also fail a compliance check.
Compatibility concerns
Applications are written for a specific OS and version. A program built for Windows will not run natively on macOS, and a Linux package will not install on Windows. Document formats, drivers and peripherals can also differ.
When a question mentions a drive shared between Windows and macOS, think exFAT. When it mentions file permissions on Windows, think NTFS.
What to remember for the exam
- Windows, macOS, iOS and iPadOS are proprietary. Linux is open source.
- NTFS is the Windows file system and supports permissions and encryption.
- FAT32 limits a single file to 4 GB. exFAT removes that limit for removable drives.
- ext4 is the common Linux file system. APFS is the current Apple file system.
- A 32 bit OS can address about 4 GB of memory.
- End of life means no more security patches.
- A distro is a packaged version of Linux.
- Apps must match the OS, version and processor type.
Common mistakes
Choosing FAT32 for large files. A video larger than 4 GB will not copy to a FAT32 drive. exFAT or NTFS is the correct choice.
Assuming NTFS works everywhere. macOS can read NTFS drives by default but cannot write to them without extra software, so it is a poor choice for sharing.
Treating Android and iOS as the same. Android is built on open source code and allows more vendor variation. iOS is closed and controlled by Apple.
Ignoring EOL. An OS still works after end of life, but it no longer gets security fixes. The right answer is usually to plan an upgrade.
Check yourself
Which file system suits a flash drive used on both Windows and macOS with files over 4 GB?
exFAT, because it supports large files and works on both systems.
What does end of life mean for an operating system?
The vendor stops providing security patches and fixes, so the system becomes a risk.
Which file system do current Apple devices use?
APFS (Apple File System), which replaced HFS+.
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