
SYM53C876/876E Data Manual
3-7
Signal Descriptions
PCI Interface Pins
Interface Control Pins
Table 3-3: PCI Interface Pins
Pin Name
Pin/Ball
Number
Type
Strength
Description
FRAME/
21, J1
S/T/S
16 mA PCI
Cycle Frame
is driven by the current master to indicate
the beginning and duration of an access. FRAME/ is
asserted to indicate that a bus transaction is beginning.
While FRAME/ is deasserted, either the transaction is in
the final data phase or the bus is idle.
Target Ready
indicates the target agent’s (selected
device’s) ability to complete the current data phase of the
transaction. TRDY/ is used with IRDY/. A data phase is
completed on any clock when used with IRDY/. A data
phase is completed on any clock when both TRDY/ and
IRDY/ are sampled asserted. During a read, TRDY/ indi-
cates that valid data is present on AD(31-0). During a
write, it indicates that the target is prepared to accept data.
Wait cycles are inserted until both IRDY/ and TRDY/ are
asserted together.
Initiator Ready
indicates the initiating agent’s (bus mas-
ter’s) ability to complete the current data phase of the
transaction. IRDY/ is used with TRDY/. A data phase is
completed on any clock when both IRDY/ and TRDY/ are
sampled asserted. During a write, IRDY/ indicates that
valid data is present on AD(31-0). During a read, it indi-
cates that the master is prepared to accept data. Wait
cycles are inserted until both IRDY/ and TRDY/ are
asserted together.
Stop
indicates that the selected target is requesting the
master to stop the current transaction.
Device Select
indicates that the driving device has
decoded its address as the target of the current access. As
an input, it indicates to a master whether any device on the
bus has been selected.
Initialization Device Select
is used as a chip select in
place of the upper 24 address lines during configuration
read and write transactions.
TRDY/
25, L1
S/T/S
16 mA PCI
IRDY/
23, K3
S/T/S
16 mA PCI
STOP/
28, L4
S/T/S
16 mA PCI
DEVSEL/
26, L2
S/T/S
16 mA PCI
IDSEL
7, E2
I
N/A