
3-15
BUS OVERVIEW
If the memory access is within the 0-to-(4GByte -1) address space, ASZ[1:0]# must be 00B. If
the memory access is within the 4Gbyte-to-(64GByte -1) address space, ASZ[1:0]# must be
01B. All observing bus agents that support the 4Gbyte (32 bit) address space must respond to
the transaction only when ASZ[1:0]# equals 00B. All observing bus agents that support the
64GByte (36- bit) address space must respond to the transaction when ASZ[1:0]# equals 00B or
01B.
The LEN[1:0]# signals determine the length of the transfer. The Pentium Pro processor will not
issue a request for a 16 byte data transfer.
In the clock that ADS# is asserted, the Aa[35:3]# signals provide a 36-bit, active-low
address as part of the request. The Pentium Pro processor physical address space is 2
36
bytes
or 64-Gigabytes (64 Gbyte). Address bits 2, 1, and 0 are mapped into byte enable signals
for 0 to 8 byte transfers.
The address signals are protected by the AP[1:0]# pins. AP1# covers A[35:24]#, AP0# covers
A[23:3]#. AP[1:0]# must be valid for two clocks beginning when ADS# is asserted. A parity
error detected on AP[1:0]# is indicated in the Error Phase. A parity signal on the Pentium Pro
processor bus is correct if there are an even number of electrically low signals in the set consist-
ing of the covered signals plus the parity signal. Parity is computed using voltage levels, regard-
less of whether the covered signals are active high or active low.
The Request Parity pin RP# covers the request pins REQ[4:0]# and the address strobe, ADS#.
RP# must be valid for two clocks beginning when ADS# is asserted. A parity error detected on
RP# is indicated in the Error Phase.
In the clock after ADS# is asserted, the A[35:3]# pins supply cache attribute information, a
deferred ID, the byte enables and other information regarding the transaction. Specifically,
the following signals are supported: ATTR[7:0]#, DID[7:0]#, BE[7:0]#, and EXF[4:0]#. The
description for these signals follows.
Table 3-6. Address Space Size
ASZ[1:0]#
Memory Address Space
Observing Agents
0
0
32-bit
32 & 36 bit agents
0
1
36-bit
36 bit agents only
1
0
Reserved
None
1
1
Reserved
None
Table 3-7. Length of Data Transfer
LEN[1:0]#
Length
BE[7:0]#
0
0
0-8-bytes
Specify granularity
0
1
16-bytes
All active
1
0
32-bytes
All active
1
1
Reserved
Содержание Pentium Pro Family
Страница 17: ...1 Component Introduction ...
Страница 26: ...2 Pentium Pro Processor Architecture Overview ...
Страница 27: ......
Страница 36: ...3 Bus Overview ...
Страница 62: ...4 Bus Protocol ...
Страница 105: ...5 Bus Transactions and Operations ...
Страница 126: ...6 Range Registers ...
Страница 131: ...7 Cache Protocol ...
Страница 135: ...8 Data Integrity ...
Страница 148: ...9 Configuration ...
Страница 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Страница 172: ...11 Electrical Specifications ...
Страница 201: ...12 GTL Interface Specification ...
Страница 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Страница 233: ...14 Thermal Specifications ...
Страница 239: ...15 Mechanical Specifications ...
Страница 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Страница 252: ...16 Tools ...
Страница 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Страница 264: ...17 OverDrive Processor Socket Specification ...
Страница 290: ...A Signals Reference ...
Страница 320: ...Index ...
Страница 328: ......