Input Output Interface in Computer Architecture:- Here we provided Input Output Interface in Computer Architecture.
Input Output Interface
Input-output interface provides a method for transferring information between internal storage and external I/0 devices. Peripherals connected to a computer need special communication links for interfacing them 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.
To resolve these differences, computer systems include special hardware components between the CPU and peripherals to supervise and synchronize all input and output transfers. These components are called interface units because they interface between the processor bus and the peripheral device. The word “Interface” is a general term for the point of contact between two parts of a system. In a digital computer system, the interface is referred to as a complementary set of signal connection points between two parts of a system. Therefore, “to interface” means to attach two or more components or systems, via their respective interface points for data exchanges between them. Two main types of interface are CPU interface that corresponds to the system bus and input-output interface that depends on the nature of the input-output device. To attach an input-output device to the CPU and input-output interface, the circuit is placed between the device and the system bus. This circuit is meant for matching the signal formats and timing characteristics of the CPU interface to those of the input-output device interface. The main function of input-output interface circuit are data conversion, synchronization and device selection. Data conversion refers to conversion between digital and analog signals, and conversion between serial and parallel data formats. Synchronation refers to matching of operating speeds of CPU and other peripherals. Device selection refers to the selection of I/O device by CPU in a queue manner. In addition, each device may have its own controller that supervises the operations of the particular mechanism in the peripheral.
Example of I/O Interface Unit