Datasheet

2−13
Table 2−8. PCI Address and Data Terminals
TERMINAL
NAME
NO.
I/O DESCRIPTION
NAME
PDV GHK
I/O
DESCRIPTION
AD31
AD30
AD29
AD28
AD27
AD26
AD25
AD24
AD23
AD22
AD21
AD20
AD19
AD18
AD17
AD16
AD15
AD14
AD13
AD12
AD11
AD10
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
171
172
175
176
178
179
167
181
184
186
187
188
189
190
191
192
205
206
207
208
173
1
2
3
5
7
8
9
10
11
12
13
E12
C12
A11
B11
E11
F11
F12
B10
F10
B09
C09
F09
E09
A08
B08
C08
B05
E06
C05
A04
B12
D01
E03
F05
E02
F03
F02
G05
F01
H06
G03
G02
I/O
PCI address/data bus. These signals make up the multiplexed PCI address and data bus on the primary
interface. During the address phase of a primary-bus PCI cycle, AD31−AD0 contain a 32-bit address or
other destination information. During the data phase, AD31−AD0 contain data.
C/BE3
C/BE2
C/BE1
C/BE0
164
193
204
4
B14
F08
F06
G06
I/O
PCI-bus commands and byte enables. These signals are multiplexed on the same PCI terminals. During
the address phase of a primary-bus PCI cycle, C/BE3
−C/BE0 define the bus command. During the data
phase, this 4-bit bus is used as byte enables. The byte enables determine which byte paths of the full 32-bit
data bus carry meaningful data. C/BE0
applies to byte 0 (AD7−AD0), C/BE1 applies to byte 1 (AD15−AD8),
C/BE2
applies to byte 2 (AD23−AD16), and C/BE3 applies to byte 3 (AD31−AD24).
PAR 203 A05 I/O
PCI-bus parity. In all PCI-bus read and write cycles, the PCI1520 calculates even parity across the
AD31−AD0 and C/BE3
−C/BE0 buses. As an initiator during PCI cycles, the PCI1520 outputs this parity
indicator with a one-PCLK delay. As a target during PCI cycles, the PCI1520 compares its calculated parity
to the parity indicator of the initiator. A compare error results in the assertion of a parity error (PERR).