io接口的作用（The role of the IO interface）.docVIP

io接口的作用（The role of the IO interface） The function of the I/O interface The host and external exchange of information is called input / output (I/O). The host and external information exchange is carried out through input / output devices. General input / output devices are the product of mechanical or electromechanical combination, such as conventional peripheral keyboard, display, printer, scanner, disk, mouse, with respect to the central processor speed is much slower. In addition, different peripheral signal form and data format are also different. Therefore, the external equipment can not be directly connected with CPU, through the corresponding circuit to complete the speed matching between them, signal conversion, and completed some control function. Usually a buffer circuit between host and peripherals called I/O interface circuit, I/O interface (Interface), as shown in figure 7.1. For the host, the I/O interface provides working status and data of external devices; for external devices, I/O memory interface all the commands and data to the host peripherals, so that the coordination between the host and peripherals. For micro computer, the design of CPU microprocessor, is not part of design interface between it and peripherals, but the input / output interface circuit design of equipment into relatively independent parts, through the micro computer hardware peripherals and they will all types of CPU connected together to form a complete. So, the input / output system of a computer should include I/O interface, I/O equipment and related control software. Comprehensive processing capacity and system of a microcomputer system reliability, compatibility, performance and price ratio, even it can on one occasion use I/O system and have a close relationship. The input / output system is an important part of the computer system, any high performance computer, if there is no high quality input / output system matched with the work of high performance computers cannot