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There are two things that can contribute to higher performance data acquisition under Windows.  First, the bandwidth between data acquisition hardware and the PC can provide higher performance.  This page illustrates that issue.  Each of the categories here use one or another form of data bus that can transfer one byte (or more) from D/A hardware to the PC at a time.  Second, the actual hardware utilizes built-in controllers to acquire data without immediate software intervention.  Usually, data that are acquired are stored in memory in the D/A system, at a speeds that directly support the actual data acquisition rate, then are transferred to the PC at some other speed, often lower than the acquisition rate.

Some bus based D/A systems support data streaming, where acquired data are copied directly to PC memory or disk, using DMA (Direct Memory Access).  These sort of systems offer rather high performance, while reducing the amount of data that the D/A system must provide for data buffering.  However, systems that utilize DMA must "plug in" directly to an internal bus, most often ISA or PCI.  This can limit the physical size of the system, thus limiting its capabilities to an extent that might be seen in systems that connect to an external bus, such as USB or IEEE-488.

There are external busses that have been designed that have even higher performance than USB, and IEEE-488. An example is IEEE-1384.  However, D/A hardware for this bus, and other high-performance external buses, have not yet been developed for general use.   As information on such such systems becomes available, I will add it to this site.



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Last modified: 11/25/09
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