CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

2.1. Identifying Major Operating System Functions

As you can read in the preceding chapter, the OS is responsible for two major functions: managing hardware devices and providing an environment in which applications can execute. One of the major applications that needs to execute is the user interface (UI), which lets the user control all other applications and their execution. In the case of Windows-based computers, this UI — the shell — is Windows Explorer. So together with hardware, this software that makes up the OS is responsible for getting things done. The hardware and software get tied together in the location where everything happens: memory.

2.1.1. Understanding memory management

Memory is the playing field where hardware and software mix. Memory management is the responsibility of the OS. The OS makes sure that the hardware and software components work within their own confines of memory. As memory resources are requested, the OS releases them either to the hardware device driver or to the application. The OS then takes steps to make sure that only the application accesses the memory areas allocated to that particular application. If an application attempts to access memory not allocated to it, the OS has to decide what to do with the application.

In all cases, attempts to access the memory space of other applications are denied. Usually, the denied application does not know what to do when this happens, so you get an application that "hangs" or terminates through ...