因此在快速的内存和相对慢速的外存（比如硬盘）之间的输入/输出（I/O）通讯就成了制约算法性能的主要瓶颈。

The resulting input/output communication (or I/O) between fast internal memory and slower external memory (such as disks) can be a major performance bottleneck.

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还可以根据用户需要，加大硬盘以扩展存储周期，或增加其他外存设备。

Users can also needs to step up the expansion of hard drive storage cycle, or to increase equipment Core other.

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当查出有移动的物体，图象就会被记录在硬盘驱动器上。外存储器是否可连接也是取决于容量。

The image is recorded on HDD when it detects moving objects. External storage is also connectable depend on the capacity.

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