amaranth VS copperhead

He probably meant Amaranth.

As an aside, the latest and active development of nMigen has been rebranded a few months ago to Amaranth and can be found here: https://github.com/amaranth-lang/amaranth . In case people googled nMigen and came to the repository that hasn't been updated in two years.

Hmm. A followup question: are there any cheats/hacks that would make it possible (if painful) to for example explore the world of USB3, PCIe, or Linux on low-end-ish ARM (eg https://www.thirtythreeforty.net/posts/2019/12/my-business-c..., based on the 533MHz https://linux-sunxi.org/F1C100s), without needing to buy equipment in the mid-4-figure/low-5-figure range, if I were able to substitute a statistically larger-than-average amount of free time (and discipline)?

For example, I learned about https://github.com/GlasgowEmbedded/glasgow recently, a bit of a niche kitchen sink that uses https://github.com/nmigen/nmigen/ to lower a domain-specific subset of Python 3 (https://nmigen.info/nmigen/latest/lang.html) into Verilog which then runs on the Glasgow board's iCE40HX8K. The project basically makes it easier to use cheap FPGAs for rapid iteration. (The README makes a point that the synthesis is sufficiently fast that caching isn't needed.)

In certain extremely specific situations where circumstances align perfectly (caveat emptor), devices like this can sometimes present a temporary escape to the inevitable process of acquiring one's first second-hand high-end oscilloscope (fingers-crossed the expensive bits still have a few years left in them). To some extent they may also commoditize the exploration of very high-speed interfaces, which are rapidly becoming a commonplace principal of computers (eg, having 10Gbps everywhere when USB3.1 hits market saturation will be interesting) faster than test and analysis kit can keep up (eg to do proper hardware security analysis work). The Glasgow is perhaps not quite an answer to that entire statement, but maybe represents beginning steps in that sort of direction.

So, to reiterate - it's probably an unhelpfully broad question, and I'm still learning about the field so haven't quite got the preciseness I want yet, but I'm curious what gadgetry, techniques, etc would perhaps allow someone to "hack it" and dive into this stuff on a shoestring budget? :)

Worth knowing that are two "nmigen"s nowadays - the one originated in M-Labs and one under a project also called nmigen:

https://github.com/nmigen/nmigen

It's a fork, made for reasons, but more actively developed. whitequark (long time author/contributor) works on this fork, and no longer the M-Labs version.

Sounds like nmigen might be a good open source successor to the project that you describe: https://github.com/nmigen/nmigen

Oh that sounds interesting. Do you know what happened to it?

I think I found it here: https://github.com/bryancatanzaro/copperhead

But I'm not sure what the state is. Looks dead (last commit 8 years ago). Probably just a proof of concept. But why hasn't this been continued?

Blog post and example: