Intel 845 Manual De Usuario
Functional Description
R
Intel
®
82845 MCH for SDR Datasheet 115
Table 16. Data Rate Control Bits
AGPCNTL
.FWCE
AGPCMD.
FWPE
AGPCMD.
DRATE
[bit 2]
AGPCMD.
DRATE
[bit 1]
AGPCMD.
DRATE
[bit 0]
MCH =>AGP Master Write
Protocol
0 0 X X X
1x
1 1 0 0 1
1x
1 1 0 1 0
2x
strobing
1 1 1 0 0
4x
strobing
5.3.6
AGP FRAME# Transactions on AGP
The MCH accepts and generates AGP FRAME# transactions on the AGP bus. The MCH
guarantees that AGP FRAME# accesses to system memory are kept coherent with the processor
caches by generating snoops to the host bus. LOCK#, SERR#, and PERR# signals are not
supported.
guarantees that AGP FRAME# accesses to system memory are kept coherent with the processor
caches by generating snoops to the host bus. LOCK#, SERR#, and PERR# signals are not
supported.
MCH Initiator and Target Operations
Table 17 summarizes MCH target operation for AGP FRAME# initiators. The cycles can be either
destined to system memory or the hub interface.
destined to system memory or the hub interface.
Table 17. PCI Commands Supported by the Intel
®
MCH (When Acting as a FRAME# Target)
C/BE[3:0]# Intel
®
MCH
PCI Command
Encoding
Cycle Destination
Response as a FRAME#
Target
Interrupt Acknowledge
0000
N/A
No response
Special cycle
0001
N/A
No response
I/O Read
0010
N/A
No response
I/O Write
0011
N/A
No response
Reserved 0100
N/A
No
response
Reserved 0101
N/A
No
response
Memory Read
0110
System memory
Read
0110
Hub
interface
No
response
Memory Write
0111
System memory
Posts data
0111
Hub interface
No response
Reserved 1000
N/A
No
response
Reserved 1001
N/A
No
response
Configuration Read
1010
N/A
No response
Configuration Write
1011
N/A
No response
Memory Read Multiple
1100
System memory
Read
1100
Hub interface
No response