There are various signals on the expansion bus that coordinate the arbitration of bus masters. Zorro II bus masters use some of the same logical signals, but their arbitration protocol is considerably different. PIC is DMA Owner (/OWN) This is asserted by the bus controller when a master is about to go on the bus and indicates that some master owns the bus. Zorro II bus masters drive this, and some Zorro III slaves may find a need to monitor it, or /BGACK, to determine who's the bus master. This is ordinarily not important to Zorro III PICs, and they may not drive this line. Slot Specific Bus Arbitration (/BRn, /BGn) These are the slot-specific /BRn and /BGn signals, where "n" refers to the expansion slot number. The bus request from each board is taken in by the bus controller and ultimately used to take over the system from the primary bus master, which is always the local master. Zorro III PICs toggle /BRn to register or unregister as a master with the bus controller. /BGn is asserted to one registered PIC at a time, on a cycle by cycle basis, to indicate to the PIC that it gets the bus for one full cycle. Bus Grant Acknowledge (/BGACK) Asserted by the bus controller when a master is about to go on the bus. As with /OWN, most Zorro III PICs ignore this signal, and none may drive it. Bus Want/Clear (/BCLR) This signal is asserted by the bus controller to indicate that a PIC wants to master the bus; Zorro III cards can use this to determine if any Zorro II bus requests are pending; Zorro III bus requests don't affect /BCLR.