Sunday, 5 November 2017

Input Output Management : Overview In Operating System

¾    The two main jobs of a computer are I/O and processing. In many cases, the main job is I/0, and the processing is merely incidental.
¾    For instance, when we browse a Web page or edit a file, our immediate interest is to read or enter some information, not to compute an answer.
¾    The role of the operating system in computer I/O is to manage and control I/O operations and I/O devices.
¾    Although related topics appear in other chapters, here we bring together the pieces to paint a complete picture of I/O.
¾    The control of devices connected to the computer is a major concern of operating-system designers.
¾    Because I/O devices vary so widely in their function and speed (consider a mouse, a hard disk, and a CD-ROM jukebox), varied methods are needed to control them.
¾    These methods form the I/O subsystem of the kernel which separates the rest of the kernel from the complexities of managing I/O devices.
¾    I/O-device technology exhibits two conflicting trends. On the one hand, we see increasing standardization of software and hardware interfaces.
¾    This trend helps us to incorporate improved device generations into existing computers and operating systems.
¾    On the other hand, we see an increasingly broad variety of I/O devices.
¾    Some new devices are so unlike previous devices that it is a challenge to incorporate them into our computers and operating systems.
¾    This challenge is met by a combination of hardware and software techniques.
¾    The basic I/O hardware elements, such as ports, buses, and device controllers, accommodate a wide variety of I/O devices.
¾    To encapsulate the details and oddities of different devices, the kernel of an operating system is structured to use device-driver modules.
¾    The device drivers present a uniform device – access interface to the I/O subsystem, much as system calls provide a standard interface between the application and the operating system.


  1. The Operating System Concepts by Silberschatz, Galvin, Gagne, 8th Edition

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