MOTOROLA
Chapter 2. Signal Descriptions
2-37
2.2.5.8.1 Parity (PAR)—Output
Following is the state meaning for PAR as an output signal.
State Meaning
Asserted—Indicates odd parity across the AD[31–0] and
C/BE[3–0] signals during address and data phases.
Negated—Indicates even parity across the AD[31–0] and
C/BE[3–0] signals during address and data phases.
2.2.5.8.2 Parity (PAR)—Input
Following is the state meaning for PAR as an input signal.
State Meaning
Asserted—Indicates odd parity driven by another PCI master or the
PCI target during read data phases.
Negated—Indicates even parity driven by another PCI master or the
PCI target during read data phases.
2.2.5.9 Parity Error (PERR)
The PCI parity error (PERR) signal is both an input and output signal on the MPC106.
2.2.5.9.1 Parity Error (PERR)—Output
Following is the state meaning for PERR as an output signal.
State Meaning
Asserted—Indicates that the MPC106, acting as a PCI agent,
detected a data parity error. (The PCI initiator drives PERR on read
operations; the PCI target drives PERR on write operations.)
Negated—Indicates no error.
2.2.5.9.2 Parity Error (PERR)—Input
Following is the state meaning for PERR as an input signal.
State Meaning
Asserted—Indicates that another PCI agent detected a data parity
error while the MPC106 was sourcing data (the MPC106 was acting
as the PCI initiator during a write, or was acting as the PCI target
during a read).
Negated—Indicates no error.
2.2.5.10 PCI Bus Request (REQ)—Output
The PCI bus request (REQ) signal is an output signal on the MPC106. Note that REQ is a
point-to-point signal. Every master has its own REQ signal. Following is the state meaning
for the REQ output signal.
State Meaning
Asserted—Indicates that the MPC106 is requesting control of the
PCI bus to perform a transaction. If the PCI bus grant (GNT) signal
is asserted before the MPC106 has a transaction to perform (that is,
the MPC106 is parked), then REQ is not asserted.
Negated—Indicates that the MPC106 does not require use of the PCI
bus.