Software and Operating Systems
What the exam tests
Software is divided into system software (operating systems, utilities, device drivers) and application software. The exam tests operating-system functions, interface types, file and process management, and the distinction between proprietary, open-source and freeware licensing.
Core rules
- An operating system manages processes, memory, files, devices and users, and provides a user interface. It is system software, not an application such as a word processor.
- Multiprogramming keeps several processes in memory; multitasking switches the CPU rapidly; multiprocessing uses more than one CPU core.
- Virtual memory uses secondary storage as an extension of RAM. Pages not currently needed are swapped to disk, allowing larger programs to run but at the cost of slower access.
- A GUI uses windows, icons, menus and pointers; a command-line interface accepts typed commands and can be efficient for automation.
Worked example
A computer has 4 GB RAM and must run a 6 GB data-processing program. With virtual memory, the OS keeps active pages in RAM and swaps inactive pages to a page file on SSD. The program can run, but repeated page faults cause disk I/O and reduce speed. Reasoning: virtual memory solves capacity, not automatically performance; adding physical RAM reduces swapping.
Traps that cost marks
Do not call an antivirus program an operating system; it is a utility. Do not equate open source with zero cost. Do not say a GUI is always faster for expert users. In process questions, a process blocked for input is not running on the CPU. Avoid confusing formatting a disk with deleting files.
Exam focus
Expect function matching, licensing comparisons and scenario questions on virtual memory or interface choice.