The ALU

• The ALU is the ``work-horse'' of the CPU.
• It is a complex combinatorial logic circuit.
• Typically, it has three inputs
  • Two operands that specify the data to be processed,
  • The operation to be performed on the operands, e.g., add, subtract, and, or, etc.
• The operation and operands are specified by the current instruction.
• Illustration: A trivial one-bit ALU that can either AND or OR the operands is easily realized.