====== 2.2.2.2.1 Operating System (OS) ======
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An [[dido:public:ra:xapend:xapend.a_glossary:o:os]], in its most general sense, is software that allows a user to run other [[dido:public:ra:xapend:xapend.a_glossary:a:application|applications]] in a computing device, as well as [[dido:public:ra:xapend:xapend.a_glossary:v:vm|Virtual Machine]] applications, which emulate another computer. While it is possible for a software application to [[dido:public:ra:xapend:xapend.a_glossary:i:interface|interface]] directly with hardware, it is not advisable from a [[dido:public:ra:xapend:xapend.a_glossary:p:portability|portability]] or lifecycle perspective. Software applications that access hardware resources or other computer components directly pose a security risk.

Operating systems provide a common, well documented, and tested set of libraries, which abstract the idiosyncrasies of the host computer away from its applications. 

An OS primarily manages a computer's hardware resources, including:
  * Input devices such as a keyboard, mouse, track pad, touch screens, camera, microphone, scanners, or sensors
  * Output devices such as display monitors, speakers, printers, or faxes
  * [[dido:public:ra:xapend:xapend.a_glossary:n:netdev|Network devices]] such as modems, router, wired and wireless [[dido:public:ra:xapend:xapend.a_glossary:i:ip|Internet Protocol]] network connections, and [[dido:public:ra:xapend:xapend.a_glossary:b:bluetooth|Bluetooth]]
  * [[dido:public:ra:xapend:xapend.a_glossary:s:storagedevice|Storage devices]] such as internal and external disks
  * Memory devices

The OS also manages a computer's:
  * CPU
  * Processes
  * Privileges
  * Cache
  * Energy, i.e., power management

===== Standards =====
==== Technical Standards ====
  * [[dido:public:ra:xapend:xapend.b_stds:tech:ieee:1003.1]] (**NOTE:** See [[dido:public:ra:xapend:xapend.a_glossary:u:unix]])
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iso:lsb]]
  * [[dido:public:ra:xapend:xapend.b_stds:defact:linuxf:linux_std_base]]

==== de facto Standards ====
  * [[dido:public:ra:xapend:xapend.b_stds:defact:apple:darwin]]
  * [[dido:public:ra:xapend:xapend.b_stds:defact:apple:ios]]
  * [[dido:public:ra:xapend:xapend.b_stds:defact:apple:macos]]
  * [[dido:public:ra:xapend:xapend.b_stds:defact:google:android]]
  * [[dido:public:ra:xapend:xapend.b_stds:defact:microsoft:windowsapi]]

===== Tools =====
  * None at this time

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