(A Level) Operating system: process management, scheduling and memory management

Learning objectives

Explain how an operating system gets the most work out of the processor, memory and input/output devices, and how its user interface spares the user the details of the hardware

Explain multitasking and what a process is, and describe the running, ready and blocked states and the event that causes each transition between them

Explain the need for scheduling, and describe and compare the first come first served, shortest job first, shortest remaining time and round robin routines, calculating waiting and turnaround times

Explain what the kernel does when an interrupt arrives, and how interrupts, including the timer interrupt, let the low-level scheduler move the processor from one process to another

Distinguish paging from segmentation, describe how a page is chosen for replacement after a page fault, and explain what causes disk thrashing