I/O systems are important part of operating systems.The two main jobs of computer are I/O system and processing. In many cases, the main job is I/O and processing is merely incidental. After we browse an internet page or edit a file, our immediate interest is to scan or enter some information; to not calculate a solution. The role of the software in pc I/O is to manage and management I/O operations and I/O devices.
I/O systems Overview –
The control of devices connect to the computer is a major concern of operating-system designers. Because I/O devices vary so widely in their function and speed, varied methods are need to control them. These methods from I/O system of the kernel; which seperates the rest of the kernel from the complexities of managing I/O devices.
I/O-device technology exhibits two conflicting trends. On the one hand, we tend to see increasing standardization of code and hardware interfaces. On the opposite hand, we tend to see associate more and more broad type of I/O devices.
I/O systems and I/O Hardware –
Computers operate a great many kinds of devices. Most fit into general categories of storage devices(disks, tapes), transmission devices and human-interface devices. Ohter devices are more specialized, such as those involved in via a joystick and foot pedals. The computer sends output commands that cause motors to move rudders and flaps and fuels to engines.
A device communicates with a computer system by sending signals over a cable or even though the air. The device communicates with the machine via a connection point, or port– for example, a serial port. If devices share a common set of wires, the connection is called as a bus. A bus is a set of wires and rigidly define protocol that specifies a set of messages that can be sent on wires. When device A has a cable that plugs into device B, and device B has a cable that plugs into device C, and device C plugs into a port on the computer, this arrangement is called as Daisy chain. A daisy chain ususally operates as a bus.
