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Merced µarch
General Info
Arch Type	CPU
Designer	Intel
Manufacturer	Intel
Introduction	June, 2001
Process	180 nm
Core Configs	1
Instructions
ISA	IA-64
Succession
McKinley

Merced was the first Itanium microarchitecture designed by Intel.

Architecture

• 10 stage pipeline
  • IPG: Get next instruction pointer
  • FET: Fetch from instruction cache
  • ROT: Instruction rotation, decoupling buffer
  • EXP: Instruction dispersal
  • REN: Register remapping
  • WLD: Word line decode
  • REG: Register file read
  • EXE: Execute
  • DET: Exception detection
  • WRB: Writeback
• Branch Predictor
  • Early zero bubble predictor using Target Address Registers controlled by the compiler
  • Two-level predictor with 4 bits of local history and a 512 entry prediction table
  • Indirect branches handled with 64 entry Multiway Branch Prediction Table
  • 64-entry Target Address Cache
  • 8 entry Return Address Stack
  • Branch predictor can resteer at ROT stage using the loop exit predictor, or compiler provided prediction hints for the third slot in a bundle.
  • Branch predictor can resteer at EXP stage for any branch
• 16K 4-way L1 Instruction Cache
• Fetch and Decode
  • Two bundles, each containing three instructions, fetched from the instruction cache every cycle
  • No decoder necessary

Block diagram of Merced