Information

e300 Processor Core Overview
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
7-4 Freescale Semiconductor
• Independent execution units and two register files
— Branch processing unit (BPU) featuring static branch prediction
— Two 32-bit integer units (IU) in the e300c3
— FPU based on the IEEE Std 754™ for both single- and double-precision operations
— Load/store unit (LSU) for data transfer between data-cache and general-purpose registers
(GPRs) and floating-point registers (FPRs)
— System register unit (SRU) that executes condition register (CR), special-purpose register
(SPR), and integer add/compare instructions. Add/compare instructions are also executed in
the IUs.
— Thirty-two 32-bit GPRs for integer operands
— Thirty-two 64-bit FPRs for single- or double-precision operands
• High instruction and data throughput
— Zero-cycle branch capability (branch folding)
— Programmable static branch prediction on unresolved conditional branches
— Two integer units with enhanced multipliers in the e300c3 for increased integer instruction
throughput and a maximum two-cycle latency for multiply instructions
— Instruction fetch unit capable of fetching two instructions per clock from the instruction cache
— A six-entry instruction queue (IQ) that provides lookahead capability
— Independent pipelines with feed-forwarding that reduces data dependencies in hardware
— 16-Kbyte, four-way set-associative instruction and data caches on the e300c3
— Cache write-back or write-through operation programmable on a per-page or per-block basis
— Features for instruction and data cache locking and protection
— BPU that performs CR lookahead operations
— Address translation facilities for 4-Kbyte page size, variable block size, and 256-Mbyte
segment size
— A 64-entry, two-way, set-associative ITLB and DTLB
— Eight-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 64-bit split-transaction internal data bus interface to the coherent system bus (CSB) with
burst transfers
— Support for one-level address pipelining on the CSB interface
— True little-endian mode for compatibility with other true little-endian devices
— Critical interrupt support
— Hardware support for misaligned little-endian accesses
— Configurable processor bus frequency multipliers as defined in the MPC8308 PowerQUICC II
Pro Processor Hardware Specification