Intel 1.70 GHz RH80532NC029256 Data Sheet

84 Datasheet

 

298517-006 

The A[35:3]# (Address) signals define a 2

36

-byte physical memory address space. When ADS# is active, 

these signals transmit the address of a transaction; when ADS# is inactive, these signals transmit 
transaction information. These signals must be connected to the appropriate pins/balls of both agents on 
the system bus. The A[35:24]# signals are protected with the AP1# parity signal, and the A[23:3]# 
signals are protected with the AP0# parity signal. 

On the active-to-inactive transition of RESET#, each processor bus agent samples A[35:3]# signals to 
determine its power-on configuration. See P6 Family of Processors Developer’s Manual for details. 

If the A20M# (Address-20 Mask) input signal is asserted, the processor masks physical address bit 20 
(A20#) before looking up a line in any internal cache and before driving a read/write transaction on the 
bus. Asserting A20M# emulates the 8086 processor's address wrap-around at the 1-Mbyte boundary. 
Assertion of A20M# is only supported in Real mode.  

The ADS# (Address Strobe) signal is asserted to indicate the validity of a transaction address on the 
A[35:3]# signals. Both bus agents observe the ADS# activation to begin parity checking, protocol 
checking, address decode, internal snoop or deferred reply ID match operations associated with the new 
transaction. This signal must be connected to the appropriate pins/balls on both agents on the system bus. 

The AERR# (Address Parity Error) signal is observed and driven by both system bus agents, and if used, 
must be connected to the appropriate pins/balls of both agents on the system bus. AERR# observation is 
optionally enabled during power-on configuration; if enabled, a valid assertion of AERR# aborts the 
current transaction. 

If AERR# observation is disabled during power-on configuration, a central agent may handle an 
assertion of AERR# as appropriate to the error handling architecture of the system.  

The AP[1:0]# (Address Parity) signals are driven by the request initiator along with ADS#, A[35:3]#, 
REQ[4:0]# and RP#. AP1# covers A[35:24]#. AP0# covers A[23:3]#. A correct parity signal is high if 
an even number of covered signals is low and low if an odd number of covered signals are low. This 
allows parity to be high when all the covered signals are high. AP[1:0]# should be connected to the 
appropriate pins/balls on both agents on the system bus.