Bus arbitration

• A device that initiates data transfers on the bus at any given time is called a bus master.

• In a computer system, there may be more than one bus master such as a DMA controller or a processor etc.

• These devices share the system bus and when a current master bus relinquishes another bus can acquire the control of the processor.

• Bus arbitration is a process by which next device becomes the bus controller by transferring bus mastership to another bus.

Bus arbitration schemes can be divided into four broad classes:

• Daisy chain arbitration.
• Centralized arbitration.
• Distributed arbitration by self-selection:
• Distributed arbitration by collision detection (e.g. Ethernet)