I/O interface

Input-Output interface
Input-output interface provides a method for transferring information between internal storage and external I/O devices. Peripherals, connected to computer need special communication links for interfacing with the central processing Unit. The purpose of the communication link is to resolve the differences that exist between the central computer and each peripheral.
The major differences are:
1-Peripherals are electromechanical and electromagnetic devices and their manner of operation is different from the operation of the CPU and memory, which are electronic devices. Therefore, a conversion of signal values may be required.
2- The data transfer rate of peripherals is usually slower than the transfer rate of the CPU, and consequently, a synchronization mechanism may be needed.
3- Data codes and formats in peripherals differ from the word format in the CPU and memory.
4- The operating modes of peripherals are different from each other and each must be controlled so as not to disturb the operation of other peripherals connected to the CPU.
I/O Bus and Interface Modules
The I/O bus consists of data lines, address lines, and control lines. The magnetic disk, printer, and terminal are employed in practically any general-purpose computer.
The magnetic tape is used in some computers for backup storage.
Each peripheral device has associated with it an interface unit.
Each interface decodes the address and control received from the
I/O bus, interprets them for the peripheral, and provides signals for
the peripheral controller.
As you can see the I/O bus from the processor is attached to all peripheral interfaces.