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.

Like buses

https://github.com/harrowm/mh882

If everyone is copying each other, now waiting for 68030 in VHDL.

No, 68060...

Kochise wrote: 21 Sep 2026 14:30 now waiting for 68030 in VHDL

Same guy as above has one in SystemVerilog.

https://github.com/harrowm/MH030

I don't see why you'd want VHDL. The world went (System) Verilog 15 years ago. And FPGA tools don't care. They mix and match modules/components in different languages no problem.

But if you needed to, you could use one of the tools available to convert to VHDL and use Formal Verification (Formality / YoSys) to prove it was identical.

VHDL, Verilog, whatever, provided we can get a cycle exact Motorola CPU implementation that we can use to create new boards and accelerators...