4-14
BUS PROTOCOL
Since agent 1 observed active BPRI# in T12, it guarantees no new request generation beginning
T13. In T13, the priority agent deasserts BPRI#. In T15, three clocks from the previous request
and at least two clocks from BPRI# deassertion agent 1, the current symmetric owner issues
request 1a.
4.1.4.8.
BNR# SAMPLING
This section illustrates how BNR# is sampled by all agents, and how the stall protocol is imple-
mented. Figure 4-9 illustrates BNR# sampling as it begins after the processor is brought out of
reset. Figure 4-10 illustrates how BNR# is sampled once the stall protocol state machine
reaches the free state. Section 4.1.3.2., “Request Stall Protocol” may be useful as reference
when reading this section.
RESET# is asserted in T1, and observed by all agents in T2. In T3 or T4, BNR# must be deas-
serted and the request stall state is initialized to the stalled state.
In T5, RESET# is driven inactive, and in T6, RESET# is sampled inactive. Any agent that re-
quires more time to initialize its bus unit logic after reset is allowed to delay transaction gener-
ation by asserting BNR# in T7. In T7, the clock after RESET# is sampled inactive, BNR# is
driven to a valid level. In T8, two clocks after RESET# is sampled inactive, BNR# is sampled
active, causing the processor to remain in the stalled state in T9.
Because the processor is in the stalled state, BNR# is sampled every 2 clocks. BNR# is sampled
asserted again in T10, so the state remains stalled. In T12, BNR# is sampled inactive. In T13,
the request stall state transitions to the throttled state. One transaction can be issued to the bus
in the throttled state, so ADS# is driven active in T13. In the throttled state, BNR# continues to
be sampled every other clock.
Figure 4-9. BNR# Sampling After RESET#
CLK
RESET#
BINIT#
ADS#
BNR#
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Summary of Contents for Pentium Pro Family
Page 17: ...1 Component Introduction ...
Page 26: ...2 Pentium Pro Processor Architecture Overview ...
Page 27: ......
Page 36: ...3 Bus Overview ...
Page 62: ...4 Bus Protocol ...
Page 105: ...5 Bus Transactions and Operations ...
Page 126: ...6 Range Registers ...
Page 131: ...7 Cache Protocol ...
Page 135: ...8 Data Integrity ...
Page 148: ...9 Configuration ...
Page 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Page 172: ...11 Electrical Specifications ...
Page 201: ...12 GTL Interface Specification ...
Page 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Page 233: ...14 Thermal Specifications ...
Page 239: ...15 Mechanical Specifications ...
Page 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Page 252: ...16 Tools ...
Page 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Page 264: ...17 OverDrive Processor Socket Specification ...
Page 290: ...A Signals Reference ...
Page 320: ...Index ...
Page 328: ......