The Unabridged Pentium 4 IA32 Processor Genealogy

Introduction to the Request Phase

Once ownership of the Request Phase signal group has been acquired (see “Pentium® 4 CPU Arbitration” on page 1149 and “Pentium® 4 Priority Agent Arbitration” on page 1165), the Request Agent uses the Request Phase signal group to broadcast the transaction request. This includes the address and transaction type, as well as additional information about the transaction. The Request Phase signal group consists of the signals introduced in Table 49-1 on page 1202.

Table 49-1. The Request Phase Signal Group

Signal(s)	Description
A[35:3]#	These signals are used to output the address as well as additional information about the transaction.
AP[1:0]#	The Address/Request parity bits.
REQ[4:0]#	The Request Type bus is used to output ...