PowerPC™ 405 Processor Block Reference Guide www.xilinx.com 21
UG018 (v2.0) August 20, 2004 1-800-255-7778
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PowerPC 405 Software Features
The PowerPC 405 processor core is an implementation of the PowerPC embedded-
environment architecture. The processor provides fixed-point embedded applications with
high performance at low power consumption. It is compatible with the PowerPC UISA.
Much of the PowerPC 405 VEA and OEA support is also available in implementations of
the PowerPC Book-E architecture. Key software features of the PowerPC 405 include:
xA fixed-point execution unit fully compliant with the PowerPC UISA:
i32-bit architecture, containing thirty-two 32-bit general purpose registers (GPRs).
xPowerPC embedded-environment architecture extensions providing additional
support for embedded-systems applications:
iTrue little-endian operation
iFlexible memory management
iMultiply-accumulate instructions for computationally intensive applications
iEnhanced debug capabilities
i64-bit time base
i3 timers: programmable interval timer (PIT), fixed interval timer (FIT), and
watchdog timer (all are synchronous with the time base)
xPerformance-enhancing features, including:
iStatic branch prediction
iFive-stage pipeline with single-cycle execution of most instructions, including
loads and stores
iMultiply-accumulate instructions
iHardware multiply/divide for faster integer arithmetic (4-cycle multiply, 35-cycle
divide)
iEnhanced string and multiple-word handl ing
iSupport for unaligned loads and unaligned stores to cache arrays, main memory,
and on-chip memory (OCM)
iMinimized interrupt latency
xIntegrated instruction-cache:
i16 KB, 2-way set associative
iEight words (32 bytes) per cache line
iFetch line buffer
iInstruction-fetch hits are supplied from the fetch line buffer
iProgrammable prefetch of next-sequential line into the fetch line buffer
iProgrammable prefetch of non-cacheable instructions: full line (eight words) or
half line (four words)
iNon-blocking during fetch line fills
xIntegrated data-cache:
i16 KB, 2-way set associative
iEight words (32 bytes) per cache line
iRead and write line buffers
iLoad and store hits are supplied from/to the line buffers