Design Of 8087 Math Coprocessor CMOS Circuit

As a high speed floating-point calculator, coprocessor is very important for the improvement of a CPU in the operation speed and precision. It has been widely used for scientific research/digital data processing and national defense. We adopt down-top-down method and our task is to design a coprocessor that is compatible with Intel 8087.8087 is the first product of Intel 80X87, it is the basis for the improvement of the 80X87 .We chose 8087 as the entrance of our research, completely analyzed it and change it from NMOS circuit to CMOS circuit.In this article, I introduce a reverse analysis and top-down design flow. Basing on the analysis of the extracted circuit, We analyzed the instruction repertoire and the micro program control unit of the 8087,the algorithms which had been adopted by the 8087 to perform basic arithmetic operations such as addition \ multiplication\square root and extend function. We simulated circuit function by instruction repertoire and performed auto-place-and-route to generate the CMOS layout, finished design checking.1.2um single poly double metal standard CMOS technology was used in this design. I used Verilog-XL from Cadence to simulate the combination operations and Silicon Ensemble to finished the automatic place and route.This article introduce a method to analyze and verify a multi-threshold circuit cell, which is not mentioned in other related documents .The method is a common way to analyze and simulate a extracted circuit. The flow to analyze and design an external circuit is a useful way in practice.