Data path (ALU + registers)

• Accumulator

  • special register
  • one of the inputs to ALU
  • output of ALU stored back in accumulator

• One-address instructions

  • operation and address of one operand
  • other operand and destinationis accumulator register
  • AC <– AC op Mem[addr]
  • "single address instructions”(AC implicit operand)

• Multiple registers

  • part of instruction usedto choose register operands

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