SBusFPGA VS satcat5

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.

I needed 128-bit and 256-bit integers on an embedded project recently.

In short, it was for fixed-point digital signal processing. The raw input and output samples were int64_t. We needed to add, subtract, multiply, and accumulate these to do filtering and linear regression with no loss of precision.

Conventional bigintegers weren't an option because the target application doesn't allow heap allocation. So we rolled our own [1] stack-allocated, fixed-width big integer class.

[1] https://github.com/the-aerospace-corporation/satcat5/blob/ma...

And here's an open-source implementation I wrote a few years back. You can skip the part at the end that handles variable-length trailing bytes, since you have a fixed-width input.

My SatCat5 project also has a few options. Anything under src/vhdl/common/cfgbus_* can be connected to AXI or Wishbone with a simple adapter.

For an all-digital solution, here's an NCO that generates an arbitrary-frequency square wave from a numeric counter.