G2 Core
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
2-4 Freescale Semiconductor
LSU for data transfer between data cache and GPRs and FPRs
SRU that executes condition register (CR), special-purpose register (SPR), and integer
add/compare instructions
Thirty-two GPRs for integer operands
Thirty-two FPRs for floating-point operands. They also can be used for general operands using
floating-point load and store operations.
High instruction and data throughput
Zero-cycle branch capability (branch folding)
Programmable static branch prediction on unresolved conditional branches
BPU that performs CR lookahead operations
Instruction fetch unit capable of fetching two instructions per clock from the instruction cache
A six-entry instruction queue that provides lookahead capability
Independent pipelines with feed-forwarding that reduces data dependencies in hardware
16-Kbyte data cache—four-way set-associative, physically addressed; LRU replacement
algorithm
16-Kbyte instruction cache—four-way set-associative, physically addressed; LRU
replacement algorithm
Cache write-back or write-through operation programmable on a per page or per block basis
Address translation facilities for 4-Kbyte page size, variable block size, and 256-Mbyte
segment size
A 64-entry, two-way set-associative ITLB
A 64-entry, two-way set-associative DTLB
Four-entry data and instruction BAT arrays providing 128-Kbyte to 256-Mbyte blocks
Software table search operations and updates supported through fast trap mechanism
52-bit virtual address; 32-bit physical address
Facilities for enhanced system performance
A 32- or 64-bit, split-transaction external data bus with burst transfers
Support for one-level address pipelining and out-of-order bus transactions
Hardware support for misaligned little-endian accesses
Added bus multipliers of 4.5x, 5x, 5.5x, 6x, 6.5x 7x, 7.5x, 8x. See Figure 2-3.
Integrated power management
Three power-saving modes: doze, nap, and sleep
Automatic dynamic power reduction when internal functional units are idle
Deterministic behavior and debug features
On-chip cache locking options for the instruction and data caches (1–3 ways or the entire cache
contents can be locked)
In-system testability and debugging features through JTAG and boundary-scan capability