A basic ALU

• This is section C.5
• They begin by constructing a 1 bit alu.
  • input lines a and b, one bit.
  • Support for or and and.
  • A mux to determine which is used to select the output.
• Build a simple adder
  • Three input bits, a, b, and CarryIn
  • Two output bits, Sum, CarryOut
• Build one of these from a truth table.
• Build a ripple carry adder (as a side issue)
• Discuss timing of the Ripple Carry Adder.
• Discuss subtraction via a ripple carry adder.
• An example