Operating Systems and Software
Core concepts
Understand the OS as a resource manager: process and thread scheduling, memory management (virtual memory, paging), file systems (NTFS, ext4, APFS), device drivers, and the user/kernel boundary. Know the difference between 32-bit and 64-bit addressing and its memory limits. Distinguish system software (OS, drivers, utilities) from application software. Understand installation types (clean install, upgrade, imaging), licensing models (perpetual, subscription, open source), and patch management. Know basic command-line concepts for Windows and Linux, such as file navigation, permissions, and process listing.
Traps in questions
A frequent trap is confusing multitasking (multiple processes) with multithreading (multiple threads within a process) and multiprocessing (multiple CPUs). Another is assuming a 32-bit OS can use more than about 4 GB of RAM - it cannot. Questions may blur virtual memory with physical RAM; virtual memory extends addressable space using disk. Do not confuse a driver with firmware. Also, an upgrade preserves settings and files while a clean install does not, and licensing terms differ between OEM, retail, and volume licenses.
Worked example / rule of thumb
A 64-bit application fails to install on a workstation. Rule of thumb: check OS architecture before blaming the installer. If the OS is 32-bit, a 64-bit application cannot run regardless of CPU capability; the fix is reinstalling a 64-bit OS, provided the CPU supports it. This architecture-first check resolves many 'application won't install' questions.
Exam focus
Expect questions on file system compatibility, permission models, patch management, and choosing the right install method for a stated goal.