82845MP Datasheet, PDF (21/157 Pages) Intel Corporation – Intel 845 Family Chipset-Mobile 82845MP/82845MZ Chipset Memory Controller Hub Mobile (MCH-M)

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Intel^® 82845MP/82845MZ Chipset-Mobile (MCH-M)
2.1. Host Interface Signals
Table 4. Host Interface Signal Descriptions
Signal Name
Type
Description
ADS#
BNR#
BPRI#
BR0#
CPURST#
DBSY#
DEFER#
DBI[3:0]#
DRDY#
HA[31:3]#
HADSTB[1:0]#
I/O
AGTL+
I/O
AGTL+
O
AGTL+
I/O
AGTL+
O
AGTL+
I/O
AGTL+
O
AGTL+
I/O
AGTL+ 4x
I/O
AGTL+
I/O
AGTL+ 2x
I/O
AGTL+ 2x
Address Strobe: The system bus owner asserts ADS# to indicate the first of two
cycles of a request phase.
Block Next Request: Used to block the current request bus owner from issuing a
new request. This signal is used to dynamically control the system bus pipeline
depth.
Bus Priority Request: The MCH-M is the only Priority Agent on the system bus. It
asserts this signal to obtain the ownership of the address bus. This signal has
priority over symmetric bus requests and will cause the current symmetric owner to
stop issuing new transactions unless the HLOCK# signal was asserted.
Bus Request 0#: The MCH-M pulls the processor bus’ BR0# signal low during
CPURST#. The signal is sampled by the processor on the active-to-inactive
transition of CPURST#. The minimum setup time for this signal is 4 HCLKs. The
minimum hold time is 2 clocks and the maximum hold time is 20 HCLKs. BR0#
should be tristated after the hold time requirement has been satisfied.
CPU Reset: The CPURST# pin is an output from the MCH-M. The MCH-M asserts
CPURST# while RSTIN# (PCIRST# from ICH3-M) is asserted and for
approximately 1 ms after RSTIN# is deasserted. The CPURST# allows the
processor’s to begin execution in a known state.
Data Bus Busy: Used by the data bus owner to hold the data bus for transfers
requiring more than one cycle.
Defer Response: Signals that the MCH-M will terminate the transaction currently
being snooped with either a deferred response or with a retry response.
Dynamic Bus Inversion: Driven along with the HD[63:0]# signals. Indicates if the
associated signals are inverted or not. DBI[3:0]# are asserted such that the
number of data bits driven electrically low (low voltage) within the corresponding
16-bit group never exceeds 8.
DBI[x]#
DBI3#
DBI2#
DBI1#
DBI0#
Data Bits
HD[63:48]#
HD[47:32]#
HD[31:16]#
HD[15:0]#
Data Ready: Asserted for each cycle that data is transferred.
Host Address Bus: HA[31:3]# connect to the system address bus. During
processor cycles the HA[31:3]# are inputs. The MCH-M drives HA[31:3]# during
snoop cycles on behalf of hub interface and AGP/Secondary PCI initiators.
HA[31:3]# are transferred at 2x rate. Note that the address is inverted on the
system bus.
Host Address Strobe: The source synchronous strobes used to transfer
HA[31:3]# and HREQ[4:0]# at the 2x transfer rate.
Strobe
HADSTB0#
HADSTB1#
Address Bits
HA[16:3]#, HREQ[4:0]#
HA[31:17]#
250687-002
Datasheet
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