In chapter 7, the function of the arithmetic unit has been defined loosely as the performance of arithmetic operations. As such, the capabilities of the arithmetic unit have been compared to those of a desk calculator. Although this analogy is valid in a general sense, the capabilities of arithmetic units exceed those of the desk calculator: in addition to arithmetic operations, certain logic data manipulations can be performed. Moreover, the particular manner in which operations are performed is influenced by the electronic design. In the following paragraphs we shall discuss three types of operations: fixed-point arithmetic operations, logic operations, and floating-point arithmetic operations. Incidental to this discussion, we shall see structures required for the implementation of the individual operations. In conclusion, several sample layouts of arithmetic units are indicated in which the individual requirements are combined.