How does the 8087 coprocessor work?

Answer 1

the 8087 is a numeric data processor(NDP) it is basically made to work with 8086/8088 processors.it cannot fetch its instruction by own so its buses(address and data buses)are simply connected to the respective buses of the processor.its instruction are recognized by the word F because each and every instruction of this coprocessor starts with the word F.this is how the min processor distinguishes between its own and the coprocessor instructions.(eg):-FADD,FSUB,etc.this coprocessor has 8-registers eacch capable of storing 80-bit temporary real numbers. the BUSY pin of the coprocessor is connected to the main processor's TEST pin.this TEST pin is active low in nature.this is because the speed of operation of the coprocessor and the main processor is different. the need of this coprocessor is because the calculation speed of maths operations containing floating real numbers is very fast than the processors like 8086/8088.during the execution of the program if the processor encounters the instruction starting with F word(11011)then it simply gives control to the 8087.initially the coprocessor is initialized by loading it with the control word which gives the idea to the 8087 that which exceptions are to be ignored.usually after the calculations the status word of the coprocessor is loaded to see which errors hve occurred.