9. ALU and the Word Length

• The size of quantities processed by ALU is the word length of the computer.

• The word length does not affect what a computer can compute.

• A computer with a smaller word length can do the same computation as one with a larger word length...

  • ...but it will take more time.

• For example, to add two 64 bit numbers,

      word length = 16 takes 4 adds.
      word length = 32 takes 2 adds.
      word length = 64 takes 1 add.