Basic DMA Concepts and Terminology

DMA is a method of transferring data between a device and main memory without intervention by the CPU. Instead of the CPU copying the data from one location to the other, the CPU initiates the copy operation and then is free to service other requests. Depending on the type of DMA device, either the device or a separate DMA controller actually copies the data. Devices such as network adapters are typically designed to support DMA, which improves both device and system performance.

Windows supports two types of DMA devices: bus-master devices and system devices, which are sometimes called “slave” devices.

Modern buses such as PCI Express typically support bus-master devices, which are now the most common type of ...

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