Operating Systems and Windows Environment
Operating Systems and the Windows Environment tests OS functions, process and memory management, file systems, Windows desktop elements, shortcuts and command-line basics.
Core rules
An operating system manages processes, memory, files, devices and security, and provides a user interface. Batch, time-sharing, real-time, distributed and mobile OS are common types. A process moves through new, ready, running, waiting and terminated states. Scheduling algorithms include FCFS, SJF, priority and round robin. The OS allocates memory, handles virtual memory and paging, and manages files through directories and extensions. In Windows, the desktop contains icons, taskbar, Start menu and notification area. Common shortcuts include Ctrl+C copy, Ctrl+V paste, Ctrl+X cut, Ctrl+Z undo, Alt+Tab switch windows, Ctrl+Alt+Del security screen and F2 rename. File extensions such as .txt, .docx, .exe and .jpg tell Windows which program to use.
Worked example
Three processes arrive together with burst times 5, 3 and 8 ms. Under FCFS in the order P1, P2, P3, waiting times are 0, 5 and 8 ms; average waiting time = (0+5+8)/3 = 4.33 ms. The first process waits 0, the second waits for the first, and the third waits for the first two.
Traps
Do not call multiprogramming the same as multitasking. Internal commands are built into the command interpreter; external commands are separate files. Shift+Delete bypasses the Recycle Bin. A file extension does not guarantee safety. In FCFS, average waiting time depends on arrival order.