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一、概述随着微计算机技术的迅速发展,出现了许多将微计算机配接A/D变换器构成的数据采集系统。但是,这种一般的采集系统,由于受微计算机接收数据的速度的限制,速度比较慢,通常在每秒10—30千字节左右。对于更高速度的要求,例如,每秒几十万或上兆字节,只有采用DMA(直接存储器存取)技术才能实现。DMA是由其内部控制器代替CPU管理数据传送的,由于DMA完成每个数据传送的时间远比CPU控制下所需时间少,因而其传送速度远高于CPU控制下的传送速度。
First, an overview With the rapid development of micro-computer technology, there have been many micro-computer A / D converter with a data acquisition system. However, this general acquisition system, due to the speed of receiving data by a microcomputer, is slower and usually takes about 10-30 kilobytes per second. For higher speed requirements, for example, hundreds of thousands or megabytes per second, only DMA (Direct Memory Access) technology can be used. DMA is managed by its internal controller instead of the CPU to manage the data transfer. Since the DMA finishes each data transfer much less than the time required by the CPU, the transfer speed is much faster than the transfer rate under CPU control.