The Operating System | OS | Part 1
The Operating System | OS
The operating system, abbreviated OS, is the set of programs from a central computing device that sits at the interface between hardware and software applications.
Intermediate between software applications and hardware, operating system serves three distinct intentions: the operating system supports the programming of hardware devices, he coordinates and optimizes the use, it offers application software interfaces programming standard that simplifies the use of material and finally realizes various functions to ensure reliability (fault tolerance, fault isolation) and the security that comes including traceability (through mechanisms of identification / authentication) , confidentiality, integrity and availability.
An operating system can be used to coordinate the use of or processor (s) and allow some time for the execution of each process, to reserve space in memory for program needs and to organize the contents of hard drives or other mass storage into files and directories. It can also be used to create the digital image that contains the human-machine interfaces of various programs and send it to monitor and receive operations performed by the user via the keyboard, mouse or other peripheral and transmit them to different programs.
Operating systems are often sold with the computer apparatus. Various software tools are provided with the operating system. They allow the user to set configuration settings of the operating system, or to perform basic operations to manipulate files.
The first operating systems were created in the 1960s. In 2009 the two families of operating systems are most popular Unix and Windows, the Windows family has a virtual monopoly on personal computers, with more than 90% market share in this sector for 15 years.
Composition Of The Operating System
An operating system is composed of a wide range of programs. The exact composition depends on the target and uses the type of computing device (PC, server, supercomputer, or embedded system) which forms the system.
If the operating system is intended to be used on a personal computer or video game console, the GUI is elegant and ergonomic. If it is intended to be used on a server, it will include a wide range of protocols and drivers for network hardware, it will multi-task and provided with access controls. Instead, the number of drivers will be restricted to a minimum and the operating system is expected to be recorded on a ROM if it is for a PDA or mobile phone. An operating system designed to be massively multiprocessor supercomputers, that is to say, it can be used on a computer with hundreds or thousands of processors.
Programming Interface
The operating system performs many actions on demand software applications. The contact point between application software and operating system is called programming interface (Application Programming Interface API). This function can be made available in software libraries, or server software that responds to requests sent by the application software.
Using the same programming interface regardless of hardware, protocol or file system in question ensures portability of applications software: given a software application can run on different computers, regardless of their configuration, particularly that which either hardware, file system or protocol.
POSIX (the acronym for Portable Operating System Interface) is a standard for the programming interface of the operating system. Many operating systems conform to this standard, including members of the UNIX family.
The Scheduler
The scheduler is the program operating system that controls the timing of other programs. In a multitasking operating system scheduler ensures the simultaneous execution of several programs (competition).
The simultaneous execution of several programs is conducted as follows: the scheduler command execution to turn each program or the computer processors, each processor executes the instruction program for a fraction second, and then the scheduler performs a context switching, suspends the execution of the current program and passes to the next program.
Continued…
