Just about every old platform seems to have a bunch of people building hardware stuff like this and writing new software. For 1980s stuff it's just all a lot si

Just about every old platform seems to have a bunch of people building hardware stuff like this and writing new software. For 1980s stuff it's just all a lot simpler than it was back then, and what was cutting edge at the time is hobbyist tier today. For software, you have modern computer power to bring to bear on the problem. Assembly/compilation/precomputation/prototyping is far quicker, and the debugging possibilities with an emulator are way ahead of anything you'd ever have had at the time. For hardware items there are freely available design tools, many cost-effective options for small production run manufacture, and for stuff like the Amiga (where nothing happens at more than about 16 MHz) logic analyzers are cheap. And the Internet makes discussing things a lot easier too!