MOTOROLA
Chapter 2. Signal Descriptions
2-35
2.2.5.3 Device Select (DEVSEL)
The device select (DEVSEL) signal is both an input and output signal on the MPC106.
2.2.5.3.1 Device Select (DEVSEL)—Output
Following is the state meaning for DEVSEL as an output signal.
State Meaning
Asserted—Indicates that the MPC106 has decoded the address and
is the target of the current access.
Negated—Indicates that the MPC106 has decoded the address and is
not the target of the current access.
2.2.5.3.2 Device Select (DEVSEL)—Input
Following is the state meaning for DEVSEL as an input signal.
State Meaning
Asserted—Indicates that some PCI agent (other than the MPC106)
has decoded its address as the target of the current access.
Negated—Indicates that no PCI agent has been selected.
2.2.5.4 Frame (FRAME)
The frame (FRAME) signal is both an input and output signal on the MPC106.
2.2.5.4.1 Frame (FRAME)—Output
Following is the state meaning for FRAME as an output signal.
State Meaning
Asserted—Indicates that the MPC106, acting as a PCI master, is
initiating a bus transaction. While FRAME is asserted, data transfers
may continue.
Negated—If IRDY is asserted, indicates that the PCI transaction is
in the final data phase; if IRDY is negated, indicates that the PCI bus
is idle.
2.2.5.4.2 Frame (FRAME)—Input
Following is the state meaning for FRAME as an input signal.
State Meaning
Asserted—Indicates that another PCI master is initiating a bus
transaction.
Negated—Indicates that the transaction is in the final data phase or
that the bus is idle.
2.2.5.5 PCI Bus Grant (GNT)—Input
The PCI bus grant (GNT) signal is an input signal on the MPC106. Note that GNT is a
point-to-point signal. Every master has its own GNT signal. Following is the state meaning
for the GNT input signal.
State Meaning
Asserted—Indicates that the MPC106 has been granted control of
the PCI bus. If GNT is asserted before the MPC106 has a transaction
to perform (that is, the MPC106 is parked), the MPC106 drives