A-level Computing 2009/AQA/Problem Solving, Programming, Operating Systems, Databases and Networking/Operating Systems/Provision of a virtual machine





The Virtual Machine is presented by the Operating System to the user, hiding all the complexities of the hardware behind layers of OS software. The final layers of the operating system are the user Interface and the Application programming interface, which calls on the services of the Operating System. Here are the layers of the OS which hide all complexities from the user, from the Hardware to the final layers of the User Interface and the API:


 * Hardware
 * Kernel - the bridge between the Hardware components and the Applications
 * Device drivers
 * Processor management
 * Memory management
 * File management
 * I/O management
 * User Interface/API

Application Programming Interface
Not all machines should be expected to have exactly the same setup. The Application Programming Interface (API) makes it possible for the same piece of program to be used on different computers. It is the layer of the software that allows the application programs to call on the services of the OS.