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5.1.概述上一章已介绍了基本的I/O接口技术和部件,也就是说用户可以根据外部设备的要求选择并行或串行接口方式。下一个问题就是处理MPU和外部设备之间的数据交换,也就是选择对数据进行调度的方式。通过I/O口对外设进行操作,通常是与MPU无关的。但是在传送数据过程中,应使1/O操作与所执行的程序同步起来。依据对数据交换进行控制和同步的方法,将输入/输出操作分为三种基本类型,即:
5.1. Overview The basic I / O interface techniques and components have been introduced in the last chapter, meaning that the user can choose the parallel or serial interface method depending on the requirements of the external device. The next issue is to deal with data exchange between the MPU and external devices, which is the way to choose to schedule the data. Operation of peripherals via I / O ports is usually independent of MPU. However, during data transfer, you should synchronize the 1 / O operation with the program being executed. According to the data exchange control and synchronization method, the input / output operations are divided into three basic types, namely: