Originally Posted by
swanscn
I am trying to understand the significance of a multi-tasking OS for IPAD or IPhone for that matter. Also, I am attempting to understand the meaning of the the term multi-tasking in this sense. Because to me this seems to be a preemptive multitasking or a task switching system. The reason I state this is to me true multi-tasking means more than one application is actually processing , as opposed to be running. The difference is huge and I do not know how that would be accomplished within this hardware architecture. A system can be preemptive while giving the illusion of multi-tasking, this would be accomplished by dispatching a background task while the user is reading a web page (for example),
Assuming you have a single core machine, Windows uses pre-emptive multi tasking where only one process may run at a time.
when the user wishes to navigate to a new page this task is dispatched and the running background task is preempted. Is this what is occurring?
The request for I/O would be passed to the operating system, since there's no point having a process in busy-wait (IE it can't render the page until it arrives) the operating system will see if another process is available to run, and if so start it. When the fetch is finished the web browser would be restarted with the data it requested. The stops and starts are completely invisible to the processes themselves.