234、Input, output interface provides a method for transferring information between internal storage and external I/O 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) Peripheral 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.In addition, each device may have its own controller that supervises the operations of the particular mechanism in the peripheral.Each peripheral device has associated with 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.It also synchronizes the data flow and supervises the transfer between peripheral and processor.(4)、Which of the following statements is true?