Sun Microelectronics
91
7. UltraSPARC External Interfaces
Figure 7-15
Arbitration: SC Arbitrates and Sends a Packet to Port
0
Figure 7-16 shows the timing when the SC relinquishes ownership after is has
driven a request packet. Port
0
asserts its request and is allowed to drive its pack-
et(s) after one dead cycle.
Figure 7-16
Arbitration: SC Gives Up Ownership to Port
0
In Figure 7-17, Port
1
encounters a quiescent bus when asserts its request. It is al-
lowed to drive its packet(s) after one arbitration cycle.
Figure 7-17
Arbitration: Bus Quiescent—Port
1
Becomes C
URRENT
D
RIVER
0
0
0
0
0
SC drives
SYSADDR &
Addr_Valid<0>
Undriven
Addr_Valid<0>
SYSADDR &
Port
0
drives
L
AST
P
ORT
D
RIVER
Req<0>
SC Request
SYSADDR
Addr_Valid<0>
Addr_Valid<0>
Cycle 0
Cycle 1
Cycle 0
Cycle 1
0
0
0
0
0
Port
0
owner
Drives
Drives
SC owner,
L
AST
P
ORT
D
RIVER
Req<0>
SC Request
SYSADDR
Addr_Valid<0>
Addr_Valid<0>
Addr_Valid<0>
Cycle 0
Cycle 1
Cycle 0
Cycle 1
0
0
0
1
1
Request
Asserted
Arbitration
Occurs
First Cycle
of Packet
L
AST
P
ORT
D
RIVER
Req<0>
Req<1>
SYSADDR
Cycle 0
Cycle 1
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