Busmastering

Bus mastering, also bus mastering (English: bus mastering ) means that the processor of a computer system temporarily take control of the bus to an adapter card, called the bus master making it. This bus master addressed independently in the sequence memory and I / O areas for the purpose of data transfer. The bus master is operating as a kind of bridge or as a stand-alone CPU. While such a secondary processor dominates the peripheral bus, the CPU is able to perform other work in the system, provided that the necessary resources are in Access. Most of the bus to the memory is gone still partly usable, and there's a time-sharing. This is particularly noticeable on modern multi-tasking operating systems, a very positive in the responsiveness noticeable, the busmaster activity is often coupled to an interrupt signal to the operating system. The adapter case has the meaning given tasks asynchronously to use for other tasks.

There are, for example, a PCI bus master and AGP bus master. Typical examples are network adapters, disk controllers, sound cards, video frame grabber and video cards that can have a bus master capability. The data transfers find this place both between the card and memory, but also between the card and card. Rather exotic representatives are crypto hardware or co-processors, called transputer boards.

The state, the CPU takes on DMA transfers, is broadly comparable with that of a bus master, so that you too often, but rather misleading, DMA bus master transfer talks.