Goals and tradeoffs in the design

This paper describes the goals and tradeoffs in the design of the MC68881 Floating Point Coprocessor. The Motorola MC68881 is a complete implementation of the proposed IEEE floating point standard on a single VLSI chip. It is a coprocessor for the MC68020 microprocessor and is a peripheral processor for other M68000 family processors. The design of the MC68881 was guided by a set of goals. This paper discusses the major goals of the MC68881 project and their impact on the design. During the definition of the architecture of the MC68881 many engineering tradeoffs were made by the design team. This paper also documents how some of these tradeoffs affected our decisions. Lastly, the paper gives enough of an overview of the MC68881 to make the discussions of the goals and tradeoffs meaningful.