PCI Bus Interface Signals 3-5
3.3.2 Address and Data Signals

Tabl e 3.3 describes Address and Data signals.

Table 3.3 Address and Data Signals

Name PQFP BGA Type Strength Description
AD[31:0] 150, 151,
153, 154,
156, 157,
159,160,3,
5, 6, 7, 9,
11–13, 28–
30, 32, 34–
36, 38, 40,
41, 43, 44,
46, 47, 49,
50
B5, C5, A4,
B4, A3, C4,
D4, A2, C2,
E5, C1, D3,
E4-E1, H5,
J1, J2, H6,
K2, J4, L1,
L2, M1, N1,
M3, L3, N3,
L4, K5, N4
T/S 8 mA
PCI Physical Dword Address and Data are
multiplexedon the same PCI pins. A bus
transactionconsists of an address phase
followedby one or more data phases.
During the first clock of a transaction,
AD[31:0] contain a 32-bit physicalbyte
address. If the commandis a DAC,
implying a 64-bit address,a second
address phase is required.During the
first phase, AD[31:0] will contain the
lower 32 bits of the address followedby
asecond phase with AD[31:0] containing
the upper 32 bits of the address.During
subsequent clocks,AD[31:0] contain
data. PCI supports both read and write
bursts. AD[7:0] define the least
significantbyte, and AD[31:24] define the
most significant byte.
C_BE[3:0] 1, 15, 26,
39 A1, F3, H3,
K4 T/S 8 mA
PCI Bus Command and Byte Enables are
multiplexedon the same PCI pins.
During the address phase of a
transaction, C_BE[3:0]/ definethe bus
command. During the dataphase,
C_BE[3:0]/ are used as byte enables.
The byte enables determine which byte
lanes carry meaningful data. C_BE[ 0]/
appliesto byte 0, and C_BE[3]/ to byte 3.
PAR 25 H1 T /S 8 mA
PCI Parity is the even parity bit that protects
the AD[31:0] and C_BE[3:0]/ lines.
During the address phase,both the
addressand command bits are covered.
During data phase, both data and byte
enables are covered.