Sun Microelectronics
90
UltraSPARC User’s Manual
Figure 7-13 shows the timing when the ownership changes between two
UltraSPARCs. In this case, Port
0
does not assert a request after its current one.
Figure 7-13 Arbitration: Change Of Ownership
Figure 7-14 shows the timing when the ownership changes between two
UltraSPARCs. In this case, Port
0
drives its first request and keeps Req<0> assert-
ed, attempting to drive back-to-back requests. The presence of Req<1> forces an
arbitration cycle, however, and Port
1
becomes CURRENT DRIVER as a result.
Figure 7-14 Arbitration: CURRENT DRIVER Loses Ownership While Asserting Request
Figure 7-15 on page 91 shows the timing when the SC takes ownership after an
UltraSPARC has driven a request packet. Since Port
0
is the receiver of the request,
SC drives Addr_Valid<0> during the first cycle of its request.
000 11
LAST PORT DRIVER
Req<0>
Req<1>
SYSADDR
Addr_Valid<0>
Addr_Valid<1>
Cycle 0 Cycle 1
Cycle 0 Cycle 1
000 01LAST PORT DRIVER
Req<0>
Req<1>
SYSADDR
Addr_Valid<0>
Addr_Valid<1>
Cycle 0 Cycle 1
Cycle 0
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