SBusFPGA VS litex

Also a VSIMM, guessing you're using the internal SX / cg14 for display ? 4 or 8 MiB ? 8 are near impossible to come by, and 4 are not much better... But they're the best way to get a truecolor display in a vintage Sun - the only one that can do some level of XRender acceleration (unless you roll your own, that is ;-) ).

In the middle you can try and design your own device and add support to whichever piece of software you need. It's an interesting exercise... (am here, doing that ;-) ).

I might be biased though :-)

New peripherals on an expansion board for a SPARCstation (90's Sun workstation).

Devices live on a custom-made SBus expansion board with an Artix-7 FPGA on it ; full project is open-source.

https://github.com/enjoy-digital/litex

they have tutorials, you can get compatible boards for around $20

With LiteX you can synthesize a VexRiscV processor. You can run Linux on it. The toolchain is pretty easy to use, as long as you use Xilinx Vivado to compile to gateware.

LiteX is a great example of a Python-first flow. However, they have chosen not to subordinate the scripting environment to a GUI toolchain - EDA vendors are unlikely to choose the same trade.

To lean these: https://github.com/enjoy-digital/litex, https://github.com/m-labs/migen

If you use LiteX to generate a VexRiscV system-on-a-chip, you can include an open source DDR DRAM PHY. This works on Xilinx Spartan-6, Spartan7Artix7/Kintex7/Virtex7 FPGAs, and Lattice ECP5 FPGAs. DDR/LPDDR/DDR2/DDR3 depending on the FPGA.

I am interested in trying out FPGAs for the purpose of running specific calculations more efficiently. Since the calculations themselves are quite complex, I would need to be able to program in a relatively high-level language. I've seen that designing SoC in Python is possible, for example with Litex (https://github.com/enjoy-digital/litex) or Amaranth (https://github.com/amaranth-lang/). I don't want to spend hundreds of hours learning about FPGAs, but I'm prepared to take on a challenge.