Emerson 752I Manual De Usuario
Local PCI Bus:
PCI Bus Control Signals
8-4
PAR:
PARITY. This is even parity across AD00-AD31 and C/BE0-C/BE3*. Parity generation is
required by all PCI agents. This three-state signal is stable and valid one clock after the
address phase, and one clock after the bus master indicates that it is ready to complete the
data phase (either IRDY* or TRDY* is asserted). Once PAR is asserted, it remains valid until
one clock after the completion of the current data phase.
required by all PCI agents. This three-state signal is stable and valid one clock after the
address phase, and one clock after the bus master indicates that it is ready to complete the
data phase (either IRDY* or TRDY* is asserted). Once PAR is asserted, it remains valid until
one clock after the completion of the current data phase.
PERR*:
PARITY ERROR. This sustained three-state line is used to report parity errors during all PCI
transactions.
transactions.
PME*:
POWER MANAGEMENT EVENT. This optional open-drain signal (pull-up resistor required)
allows a device to request a change in the power state. Devices must be enabled by soft-
ware before asserting this signal. (The Katana
allows a device to request a change in the power state. Devices must be enabled by soft-
ware before asserting this signal. (The Katana
752i does not support this signal.)
PRESENT*:
PRESENT. When grounded, this signal indicates to a carrier that a PMC module is installed.
(The Katana
(The Katana
752i does not support this signal.)
RESET_OUT*:
RESET OUTPUT. This optional output signal may be used to support another source. To
avoid reset loops, do not use RST* to generate RESET_OUT*.
avoid reset loops, do not use RST* to generate RESET_OUT*.
REQ*:
REQUEST. This output pin indicates to the arbiter that a particular master wants to use the
bus.
bus.
RST*:
RESET. The assertion of this input line brings PCI registers, sequencers, and signals to a con-
sistent state.
sistent state.
SERR*:
SYSTEMS ERROR. This open-collector output signal is used to report any system error with
catastrophic results.
catastrophic results.
STOP*:
STOP. This is a sustained three-state signal used by the current target to request that the
bus master stop the current transaction.
bus master stop the current transaction.
TRDY*:
TARGET READY. This is a sustained three-state signal that indicates the target’s ability to
complete the current data phase of the transaction.
complete the current data phase of the transaction.