The Unabridged Pentium 4 IA32 Processor Genealogy

BNR# Behavior During Runtime

Figure 48-8 on page 1200 illustrates BNR# behavior during run-time.

1. The Priority Agent had acquired ownership of the Request Phase signal group in the clock prior to clock 1 and initiated a transaction request. It deasserted BPRI# as it did so to yield ownership to physical processor 0 (BREQ0# was asserted). The indicator is in the Free state and BNR# is being sampled by all Request Agents two clocks after ADS# is sampled asserted.

2. On clock one, physical processor 0 samples BPRI# deasserted, indicating that it will be the next owner of the Request Phase signal group.

3. Physical processor 0 initiates a transaction request at the start of clock two (its indicator is in the Free state, giving it permission to do so).

4. At the ...