Input Output management in operating system I O

ﺍﻟﻤﺤﺎﺿﺮﺓ ﺍﻟﺜﺎﻣﻨﺔ Input Output management in operating system

I/ O management in operating system - In computing input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world possibly a human, or another information processing system. - Inputs are the signals or data received by the system - outputs are the signals or data sent from it.

Examples for I/O a keyboard or a mouse may be an input device for a computer, while monitor sand printers are considered output devices for a computer. - Devices for communication between computers, such as modems and network cards, typically serve for both input and output

Goals for I/O • Users should access all devices in a uniform manner. • Devices should be named in a uniform manner. • The OS, without the intervention of the user program, should handle recoverable errors. • The OS must maintain security of the devices. • The OS should optimize the performance of the I/O system.

Types of the I/O Divided input and output devices into two group were entitled 1 - (Block Devices) group 2 - and is entitled (Character Devices ): -

Types of the I/O 1 - (Block Devices) group: The first category is a hardware information can be stored in a fixed size blocks and each block has a private address, and the ability to perform read and write operations, research and transition. The drive is one of the most common devices entitled.

Types of the I/O 2 - Character Devices ): The second category is called non-mapped devices. They send and receive signals from smooth. They also can not store data in addition to the inability to perform any of the operations of reading or writing, research or transition. The printers and devices is one of the most common entitled

Levels of software input and output devices User Level I / O Software Device Independent Operating System Software Device Drivers Interrupt Handlers Hard Ware

Levels of software input and output devices Interrupt Handlers: Counties are considered a de facto and can not be avoided, and should always be hidden away from the user. So for Every by only a small part of the operating system. The best way to hide is to make the driver who starts the process of input / output depends pending completion of the process of input / output

Levels of software input and output devices Device Drivers - This program is part of the operating system that is guided by the command console, it also retains a number of records within the console titles - Primary function of this program is receiving applications from software input in the upper layer software, and then the implementation of these applications in coordination with the console

Levels of software input and output devices Device Independent Operating System Software: The software layer top layer of management software unit, so that its functions are integrated in the program with layer management unit. The main tasks of this layer in the following: A) is a layer of overlap between the user layer and layer management unit. B) Designation of the physical components Device Naming. C) Reservation of the cache memory in the unit Buffering. D) book storage capacity in units of input and output. E) Identify the errors.

Levels of software input and output devices Software User Level I / O User Level /twa It is the last layer of the working classes, which provides services for the user to use the input and output devices different in the computer, so that the user dials the service programs of this layer, which in turned this request to the layered software up and so to be performed the service Level I / O Software