exxos's Atari, Amiga & retro forum

For what it's worth :

https://github.com/mattuna15/68881-fpga

Interesting!

It's very big in terms of FPGA utilisation so I don't think we'll see it alongside cores in MiSTer. I don't know if it's representative of the original silicon, I don't know how much RAM, registers, ALU elements there were in the original.

Very nice thing to have though

There's a "LITE" version (see "fpu_lite_g => true"), the same as the 040 subset that needs the software emulation package for the missing instructions.

I'm not sure how useful the Lite version will be for non 040 implementations? At least for pre-compiled software?

IIUC 040 uses a different method of accessing the registers than 020 and 030? They use the co-processor bus and Line-F traps or something (this is not my area of expertise). There is a chance software compiled for those CPU/FPU combos are likely to expect the full instruction set? But who knows?

Nice thing to have definitely.

Obviously is "saves" ~57-60% LUT, hence make it possible to fit smaller FPGA.