8087 co-processor

Thats sounds so funny, but it might not be such a bad idea, only look for a much faster unit that is comparable in functionality. One might suggest a Pentium4 or Athlon but that would be tooo fast to interface to. I don't know what the equiv of a ready made 8087 would be today at comparable FPGA interface speeds. Perhaps one of the FP DSPs, or just do it in FPGA with a cpu + FP core and some hardwork. It really depends on exactly what you want to do in FP.

johnjakson at usa ..

No. Throw it away. You would need an 8086 style interface just to talk to it.

-- Mike Treseler

The 80287 interface might be a little easier. The 8087 worked by snooping the bus while the 8086 was running, then when it saw an 8087 opcode being fetched went on to fetch the rest of the bytes/words it needed. The 80287, I believe, worked in the more obvious way where the processor wrote/read from it. The 80287 also has a clock asynchronous to the bus interface, which might make it easier.

Doing floating point in an FPGA tends to use a lot of CLBs, especially for add/subtract which seem easy. But one might be able to do an iterative implementation faster than the 80287, or a fully pipelined one at full speed.

-- glen