Input Output Devices

Input Output
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 anotherinformation processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it.

The term can also be used as part of an action; to "perform I/O"is to perform an input or output operation. I/O devices are used by a person (or other system) to communicate with a computer. For instance, a keyboard or a mouse may be an input device for a computer,while monitors and 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.Input Output Both

Interface
An I/O interface is required whenever the I/O device is driven bythe processor. The interface must have necessary logic to interpret the device address generated by the processor. Handshaking should be implemented by the interface using appropriate commands (likeBUSY, READY, and WAIT), and the processor can communicate with an I/O device through the interface. If different data formats are being exchanged, the interface must be able to convert serial data toparallel form and vice-versa. There must be provision for generating interrupts and the corresponding type numbers for further processing by the processor if required.

Higher-level implementationHigher-level operating system and programming facilities employ separate, more abstract I/O concepts and primitives.

Addressing mode
There are many ways through which data can be read or stored inthe memory. Each method is an addressing mode, and has its own advantages and limitations.
Direct addressing
In this type of address of the data is a part of the instructions itself. When the...