Manual Number: 40110-005-2
Page 31
The PCI Local Bus signals are described below and may be categorized into the following func-
tional groups:
•
System Pins
•
Address and Data Pins
•
Interface Control Pins
•
Arbitration Pins (Bus Masters Only) Error Reporting Pins
•
Interrupt Pins (Optional)
•
Cache Support Pins (Optional)
•
64-Bit Bus Extension Pins (Optional)
•
JTAG/Boundary Scan Pins (Optional)
A # symbol at the end of a signal name indicates that the active state occurs when the signal is at a
low voltage. When the # symbol is absent, the signal is active at a high voltage.
The following are descriptions of the PCI Local Bus signals.
ACK64# (optional)
Acknowledge 64-bit Transfer, when actively driven by the device that has positively decoded
its address as the target of the current access, indicates the target is willing to transfer data using
64bits. ACK64# has the same timing as DEVSEL#.
AD[31::00]
Address and Data are multiplexed on the same PCI pins. A bus transaction consists of an address
phase followed by one or more data phases. During the address phase, AD[31::00] contain a
physical address (32 bits). During data phases, AD[07::00] contain the least significant byte
(lsb) and AD[31::24] contain the most significant byte (msb).
AD[63::32] (optional)
Address and Data are multiplexed on the same pins and provide 32<N>additional bits. During
an address phase (when using the DAC command and when REQ64# is asserted), the upper
32bits. of a 64-bit address are transferred; otherwise, these bits are reserved but are stable and
indeterminate. During a data phase, an additional 32bits. of data are transferred when REQ64#
and ACK64# are both asserted.
C/BE[3::0]#
Bus Command and Byte Enables are multiplexed on the same PCI pins. During the address phase
of a transaction, these pins define the bus command; during the data phase they are used as byte
enables. The byte enables are valid for the entire data phase and determine which byte lanes carry
meaningful data. C/applies to byte(lsb) and applies to byte 3 (msb).
Summary of Contents for SB686P Series
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