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BDM-610000087 Rev A Chapter 3: Connecting the cpuModule 53
PCI-104 PCI Bus Signals
The following are brief descriptions of the PC-104 PCI bus signals.
Address and Data
AD[31:00] — Address and Data are multiplexed. A bus transaction consists of an address cycle
followed by one or more data cycles.
C/BE[3:0]# — Bus Command/Byte Enables are multiplexed. During the address cycle, the command
is defined. During the Data cycle, they define the byte enables.
PAR — Parity is even on AD[31:00] and C/BE[3:0]# and is required.
Interface Control Pins
FRAME# — Frame is driven by the current master to indicate the start of a transaction and will remain
active until the final data cycle.
TRDY# — Target Ready indicates the selected devices ability to complete the current data cycle of the
transaction. Both IRDY# and TRDY# must be asserted to terminate a data cycle.
IRDY# — Initiator Ready indicates the master's ability to complete the current data cycle of the
transaction.
STOP# — Stop indicates the current selected device is requesting the master to stop the current
transaction.
DEVSEL# — Device Select is driven by the target device when its address is decoded.
IDSEL[3:0] — Initialization Device Select is used as a chip-select during configuration.
LOCK# — Lock indicates an operation that may require multiple transactions to complete.
Error Reporting
PERR# — Parity Error is for reporting data parity errors.
SERR# — System Error is for reporting address parity errors.
Arbitration (Bus Masters Only)
REQ[3:0]# — Request indicates to the arbitrator that this device desires use of the bus.
GNT[3:0]# — Grant indicates to the requesting device that access has been granted.
System
CLK — Clock provides timing for all transactions on the PCI bus.
RST# — Reset is used to bring PCI-specific registers to a known state.
Interrupts
INTA# — Interrupt A is used to request Interrupts.
INTB# — Interrupt B is used to request Interrupts only for multi-function devices.
INTC# — Interrupt C is used to request Interrupts only for multi-function devices.
INTD# — Interrupt D is used to request Interrupts only for multi-function devices.