Parallel Decode/Instruction Issue

• Need to determine for multiple instructions:

  • Are the operands available, and if so, fetch them
  • Which execution units do the instructions go to (choose from multiple execution units)

• Superscalar implementations may use multiple stages for decode/issue

  • PPC 601, PPC 604, UltraSparc take cycles, Alpha 21064 takes 3 cycles, Pentium Pro requires 4.5 cycles

Previous slide

Next slide

Back to first slide

View graphic version