Changes

* Hardware Abstraction, which allows programs to make use of hardware without having to know about the specifics of any given hardware device. It is responsible for displaying the graphics on screen and outputting sound to the speakers, controlling input from the mouse and keyboard, and allowing [[hardware]] to work properly.  Usually this is implemented in the [[BIOS]] or a separate HAL (Hardware Abstraction Layer).

* Hardware Abstraction, which allows programs to make use of hardware without having to know about the specifics of any given hardware device. It is responsible for displaying the graphics on screen and outputting sound to the speakers, controlling input from the mouse and keyboard, and allowing [[hardware]] to work properly.  Usually this is implemented in the [[BIOS]] or a separate HAL (Hardware Abstraction Layer).

* Load programs from secondary stores into memory and execute them.

* Load programs from secondary stores into memory and execute them.

* File Systems, which handle storing and retrieving files stored on hard disks, USB drives, magnetic tapes, and CDROM/DVDROMs.

* [[File System]]s, which handle storing and retrieving files stored on hard disks, USB drives, magnetic tapes, and CDROM/DVDROMs.

* Security.  Prevent unauthorized access to system resources.

* Security.  Prevent unauthorized access to system resources.

* Multiprocessing. Allow multiple programs to run simultaneously and share system resources.

* Multiprocessing. Allow multiple programs to run simultaneously and share system resources.