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PowerPC™ 405 Processor Block Reference Guide www.xilinx.com 51
UG018 (v2.0) August 20, 2004 1-800-255-7778
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Instruction-Side PLB Interface I/O Signal Descriptions
The following sections describe the operation of the instruction-side PLB interface I/O
signals.
Throughout these descriptions and unless otherwise noted, the term clock refers to the PLB
clock signal, PLBCLK (see “PLBCLK (Input)” for information on this clock signal). The
term cycle refers to a PLB cycle. To simplify the signal descriptions, it is assumed that
PLBCLK and the PowerPC 405 clock (CPMC405CLOCK) operate at the same frequency.
Table 2-7: Instruction-Side PLB Interface Signal Summary
Signal
I/O
Type
If Unused Function
C405PLBICUREQUEST O No Connect Indicates the ICU is making an instruction-fetch
request.
C405PLBICUABUS[0:29] O No Connect Specifies the memory address of the instruction-fetch
request. Bits 30:31 of the 32-bit address are assumed to
be zero.
C405PLBICUSIZE[2:3] O No Connect Specifies a four word or eight word line-transfer size.
C405PLBICUCACHEABLE O No Connect Indicates the value of the cacheability storage
attribute for the target address.
C405PLBICUU0ATTR O No Connect Indicates the value of the user-defined storage
attribute for the target address.
C405PLBICUPRIORITY[0:1] O No Connect Indicates the priority of the ICU fetch request.
C405PLBICUABORT O No Connect Indicates the ICU is aborting an unacknowledged
fetch request.
PLBC405ICUADDRACK I 0 Indicates a PLB slave acknowledges the current ICU
fetch request.
PLBC405ICUSSIZE1 I 0 Specifies the bus width (size) of the PLB slave that
accepted the request.
PLBC405ICURDDACK I 0 Indicates the ICU read-data bus contains valid
instructions for transfer to the ICU.
PLBC405ICURDDBUS[0:63] I 0x0000_0000
_0000_0000
The ICU read-data bus used to transfer instructions
from the PLB slave to the ICU.
PLBC405ICURDWDADDR[1:3] I 0b000 Indicates which word or doubleword of a four-word
or eight-word line transfer is present on the ICU read-
data bus.
PLBC405ICUBUSY I 0 Indicates the PLB slave is busy performing an
operation requested by the ICU.
PLBC405ICUERR I 0 Indicates an error was detected by the PLB slave
during the transfer of instructions to the ICU.