Pentium
III Processor Mobile Module MMC-2
Featuring Intel
SpeedStep Technology
10
Datasheet
243356-006
3.1.4
PCI Signals
Table 4 provides descriptions of the PCI signals.
Table 4.
PCI Signal Descriptions
Name
Type
Voltage
Description
AD[31:0]
I/O
PCI
V_3
Address/Data: The standard PCI address and data lines. The
address is driven with FRAME# assertion, and data is driven or
received in the following clocks.
C/BE[3:0]
I/O
PCI
V_3
Command/Byte Enable: The command is driven with FRAME#
assertion, and byte enables corresponding to supplied or requested
data are driven on the following clocks.
FRAME#
I/O
PCI
V_3
Frame: Assertion indicates the address phase of a PCI transfer.
Negation indicates that the cycle initiator desires one more data
transfer.
DEVSEL#
I/O
PCI
V_3
Device Select: The 82443BX Host Bridge drives this signal when a
PCI initiator is attempting to access DRAM. DEVSEL# is asserted at
medium decode time.
IRDY#
I/O
PCI
V_3
Initiator Ready: Asserted when the initiator is ready for a data
transfer.
TRDY#
I/O
PCI
V_3
Target Ready: Asserted when the target is ready for a data transfer.
STOP#
I/O
PCI
V_3
Stop: Asserted by the target to request the master to stop the current
transaction.
PLOCK#
I/O
PCI
V_3
Lock: Indicates an exclusive bus operation and may require multiple
transactions to complete. When LOCK# is asserted, nonexclusive
transactions may proceed. The 82443BX supports lock for CPU
initiated cycles only. PCI initiated locked cycles are not supported.
REQ[4:0]#
I
PCI
V_3
PCI Request: PCI master requests for the PCI.
GNT[4:0]#
O
PCI
V_3
PCI Grant: Permission is given to the master to use PCI.
PHOLD#
I
PCI
V_3
PCI Hold: This signal comes from the expansion bridge. It is the
bridge request for PCI. The 82443BX Host Bridge will drain the DRAM
write buffers, drain the processor-to-PCI posting buffers, and acquire
the host bus before granting the request via PHLDA#. This ensures
that GAT timing is met for ISA masters. The PHOLD# protocol has
been modified to include support for passive release.
PHLDA#
O
PCI
V_3
PCI Hold Acknowledge: This signal is driven by the 82443BX Host
Bridge to grant PCI to the expansion bridge. The PHLDA# protocol
has been modified to include support for passive release.
PAR
I/O
PCI
V_3
Parity: A single parity bit is provided over AD[31:0] and C/BE[3:0]#.