Operating Systems

The operating system (O/S) is the most important program that you will use on your computer. Every general-purpose computer must have an operating system to run other programs. Here are the main areas that the O/S is responsible for:

The O/S coordinates, schedules and executes all other program activities. It also must supervise the allocation and dealloaction of memory and the movement of data within the system's types of memory (registers, CPU cache, RAM, and auxiliary storage).
User Interface: The Graphical User Interface includes the windows, menus, buttons and so on that you use to interact with the computer.
Task Manager: Most O/S today are multitasking. This is the ability to execute multiple programs at the same time. When you have several programs running simultaneously the O/S allows you to easily switch back and forth.
File Manager: All the data stored on the various storage devices such as hard disk, CD-ROM, memory card and so on is managed by the O/S. Saving, opening, copying, deleting your files is all controlled by the O/S.
Device Manager:

The O/S controls all the peripheral devices (like printers and monitors and so on) by sending them commands in their own special hardware language. There are special "subprograms" in the O/S that know how to communicate with each device. These subprograms are called drivers. Each new hardward device added to the computer may require new drivers for that device to be installed.

Security Manager:

Access to the computer or to certain files may be limited and require passwords. The O/S controls access and maintains activity logs as well as providing backup and recovery procedures in the event of a system failure.

The operating system for Personal Computers has a lot of work to do but in large computer systems, it has even greater responsibilities and powers. It is like a traffic cop - it makes sure that different programs and users running at the same time do not clash with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.

Here are some additional features of operating systems that are worth learning about.

This is when two or more users can run programs at the same time. Some operating systems permit hundreds or even thousands of users at the same time.
Multiprocessing: When a computer has more than one microprocessor as part of the CPU it requries a special O/S to manage the multiple cores or microprocessors. New CPUs for desktop and server computers offer two and four cores in a single CPU. Predictions from Intel suggest that there will be hundreds of cores in a single CPU in the future.
Multitasking: The term that describes an operating system's ability to run more than one program at the same time.
Multithreading : Certain microprocessors and O/S allow different parts of a single program to run concurrently.
Real-time :

Real-time operating systems must respond to input instantly. O/S that control car engines, pacemakers, airplane control systems must operate in real-time otherwise it may lead to a critical failure of the complete system. General-purpose operating systems, such as Windows and Linux, are not real-time.

Embedded system:

This is a combination of hardware and O/S in special-purpose system in which the computer is completely encapsulated by or dedicated to the device or system it controls. Cell phones, ATMs, video game consoles are considered embedded systems.




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