Digital VS of816

Theres the open source Digital (https://github.com/hneemann/Digital) which can run simulations but then export Verilog. If you have an ICE40 based GPU then in theory you can then use open source tools (like apio) to get that onto your FPGA. I've seen some impressive fpga tasks being generated by that.

I'm early in my learning of FPGA and have done nandgame and some other non-HDL circuit learnings. I have gone back and forth if I want to design my project via HDL or via something like Digital. There's not an easy pro/con either way.

Used the recommended JRT https://adoptium.net/

Wandered through the https://github.com/hneemann/Digital site and saw past issues with JRT but no obvious solution.

I have a couple hundred GALs of same or similar model number of new old stock

Check if https://github.com/hneemann/Digital and/or Logisim are for you.

someone posted a logic gate graph some days ago which sent me through a loop of remaking a 4bit multiplier i designed in Digital Logic, in desmos. unfortunately everything is pretty much explicitly defined and put together as to maintain only the appearance of this exact circuit, so theres no ui for placing components drawing wires and building your own circuits. yet ;]

This is my favorite book and I read it while trying to create the circuits myself before learning the chapter using digital - it's very enlightening and I recommend you do the same

Digital

The Digital application can generate a circuit based on a truth table. An example...

I also found this Forth implementation that might work.

There are several Forth versions for the 65816 that I've found online. Some are specialized to specific hardware but can be modified. Michael Guidero's OF816 is designed to be easily ported to new systems. I got it running on my 65816 emulator without much problem. It handles banked memory and uses a good subset of 65816 features.

One issue I had when I was finishing up my emulator was finding substantial programs to test that weren't designed for a particular architecture. I'm focused mainly on text-based programs, so it might not be as interesting for your emulation, but OF816, by Michael Guidero, is a larger program designed to be easily ported to new 65816-based systems. Here's my fork of it for my py65816 emulator as another example of porting it to an emulator. If you don't want to bother creating your own port or creating a binary, here's one with I/O mapped to 7FC0 and 7FE0 respectively. Load it at $8000 and reset to start. It uses bank 0 and bank 1 so you need to have at least those modeled.