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Local PCI Bus: PCI Bus Control Signals
10006024-04 Katana
®
752i User’s Manual
8-3
ACK64*, REQ64*: These sustained three-state output signals tell a 64-bit PCI device whether to use the 64-bit
or the 32-bit data width. Since the Katana
®
752i is a 32-bit board, these signals are tied off
to indicate the 32-bit data width.
AD00-AD31: ADDRESS and DATA bus (bits 0-31). These three-state lines are used for both address and
data handling. A bus transaction consists of an address phase followed by one or more data
phases.
C/BE0*-C/BE3*: BUS COMMAND and BYTE ENABLES. These three-state lines have different functions
depending on the phase of a transaction. During the address phase of a transaction these
lines define the bus command. During a data phase the lines are used as byte enables.
CLK: CLOCK. This is an input signal that provides timing for PCI transactions. (This is unused,
since the Katana
®
752i generates its own PCI clock signal.)
DEVSEL*: DEVICE SELECT. This sustained three-state signal indicates when a device on the bus has
been selected as the target of the current access.
EREADY: READY. This signal is an input for Monarch devices and an output for non-Monarch devices.
It indicates that all modules are initialized and the PCI bus is ready to be enumerated.
FRAME*: CYCLE FRAME. This sustained three-state line is driven by the current master to indicate the
beginning of an access, and continues to be asserted until transaction reaches its final data
phase.
GNT*: GRANT. This input signal indicates that access to the bus has been granted to a particular
master. Each master has its own GNT*.
IDSEL: INITIALIZATION DEVICE SELECT. This input signal acts as a chip select during configuration
read and write transactions.
INTA*, INTB*, INTC*, INTD*:
PMC INTERRUPTS A, B, C, D. These interrupt lines are used by PCI devices to interrupt the
host processor.
IRDY*: INITIATOR READY. This sustained three-state signal indicates that the bus master is ready
to complete the data phase of the transaction.
M66EN: ENABLE 66 MHZ. When grounded, this signal prevents 66 MHz operation of the PCI bus.
MONARCH*: MONARCH. When this signal is grounded, it indicates that the Katana
®
752i baseboard is a
Monarch and must provide PCI bus enumeration and interrupt handling.
LOCK*: LOCK. This sustained three-state signal indicates that an automatic operation may require
multiple transactions to complete. (The Katana
®
752i does not support this signal.)