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1 definition found
 for bus master
From The Free On-line Dictionary of Computing (30 December 2018) :

  bus master
  bus mastering
  First Party DMA
  
      The device in a computer which is driving the
     address bus and bus control signals at some point in time.
     In a simple architecture only the (single) CPU can be bus
     master but this means that all communications between
     ("slave") I/O devices must involve the CPU.  More
     sophisticated architectures allow other capable devices (or
     multiple CPUs) to take turns at controling the bus.  This
     allows, for example, a network controller card to access a
     disk controller directly while the CPU performs other tasks
     which do not require the bus, e.g. fetching code from its
     cache.
  
     Note that any device can drive data onto the data bus when
     the CPU reads from that device, but only the bus master drives
     the address bus and control signals.
  
     Direct Memory Access is a simple form of bus mastering where
     the I/O device is set up by the CPU to read from or write to
     one or more contiguous blocks of memory and then signal to the
     CPU when it has done so.  Full bus mastering (or "First Party
     DMA", "bus mastering DMA") implies that the I/O device is
     capable of performing more complex sequences of operations
     without CPU intervention (e.g. servicing a complete NFS
     request).  This will normally mean that the I/O device
     contains its own processor or microcontroller.
  
     See also distributed kernel.
  
     (1996-08-26)
  

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