Operating System: Difference between revisions
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Before a computer can do much, it'll need some software to provide basic system services. This is basically what an operating system (or OS for short) does; it manages devices and memory, keeps applications from stepping on each other's toes, and provides an [[Application Programming Interface]] (sometimes many APIs) for applications to use.
In the early days of computing (and even now, on special applications like microcontrollers), computers didn't have OSes; you programmed them directly in [[Binary Bits and Bytes]], and on some ''really'' old machines (including ENIAC, the first practical electronic computer, and IBM's old card-counting machines), you didn't have program memory at
As PCs got cheaper and more powerful, full operating systems started being written for them, with richer APIs, actual memory protection and "demand paging" (which allowed applications to use "virtual" memory that actually lived in a file on disk). Pretty much all PC OSes now include this as a matter of course.
Most operating systems work as four separate layers of software running in the computer. The lowest layer, the one that interacts directly with the hardware, is known as the ''kernel'', the core of the operating system, which handles stuff like memory management, program input and output, communication with your hardware, and might have other additional
See also:
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