It also provides an interface for the user to run the application, called application program interface (API). This enables the programs to run on the computer. Even if a particular computer is unique, an operating system can ensure that applications continue to run when hardware upgrades and updates occur.
It is not just Microsoft who has created Operating Systems, although they are the most popular. Other operating systems include Apple, Linux, 3Com and Sun Solaris etc.
Device Management - Input and output Management
Drivers in the Device management part of the software manage the pathway between the motherboard and the hard drive. The driver's function is to be the translator between the electrical signals of the hardware subsystems and the highlevel programming languages of the operating system and application programs. The majority of hardware is used only occasionally and the drivers do not often need to be run by the operating system permanently. The operating system will frequently assign high-priority blocks to drivers so that the hardware resource can be released and readied for further use as quickly as possible.
Drivers are separate from the operating system so that new functions can be added to the driver and to improve the performance of the hardware.
Managing all the resources of the computer system is a large part of the operating system's function.
Processor Management
The processor management makes sure that the applications receive enough of the processor's time to function properly. Also it makes sure that the processor is used as much as possible for real work in each cycle.
The operating system does this by scheduling the work done by the processor.
In a multi-tasking operating system, for example Windows XP. The processor management runs to give the appearance that the CPU is doing more than one thing at a time. This is not true. In order to give the appearance of lots of things happening at the same time, the operating system has to switch between different processes thousands of times a second. Here's how it happens:
• A process occupies a certain amount of RAM. It also makes use of registers, stacks and queues within the CPU and operating system memory space.
• When two processes are multi-tasking, the operating system allots a certain number of CPU execution cycles to one program.
• After that number of cycles, the operating system makes copies of all the registers, stacks and queues used by the processes, and notes the point at which the process paused in its execution.
• It then loads all the registers, stacks and queues used by the second process and allows it a certain number of CPU cycles.
• When those are complete, it makes copies of all the registers, stacks and queues used by the second program, and loads the first program.
User Interface
The User Interface (UI) brings structure to the interaction between a user and the computer. The user interface allows the user to use the computer more simply with the aid of a mouse or keyboard. This is an input User Interface
The (GUI) is what is displayed on the monitor. A GUI is the graphical user interface to a computer, and its elements include such things as: windows, icons, and buttons, cursors and scroll bars. This is an output user interface.
The user interfaces are vital for the computer to be used by a human.
Memory and File Management
Everything the computer does is at some time written to the RAM by the operating system. For the operating system to be able to do this, firstly memory boundaries must be set up for individual applications, which will be stored in the RAM.
When the allocated space in the RAM is full, and the processor is not using the information stored there it is then moved by the operating system to the hard disk in what is called Virtual Memory. Hard disk storage is only one of the memory types that must be managed by the operating system, and is the slowest compared to other storage types. The object of the operating system is to balance between what is and isn't needed it the RAM and prepare the RAM so the processor can use it trouble free.