https://www.vogons.org/ https://www.vogons.org/ For the more mainstream retro machines and hardware. https://forum.vcfed.org/ https://forum.vcfed.org/ For the

https://www.vogons.org/ https://www.vogons.org/ For the more mainstream retro machines and hardware. https://forum.vcfed.org/ https://forum.vcfed.org/ For the rarer esoteric stuff (but still loads of old Macs, DOS machines, Amigas and 8-bit stuff) There loads of others, often machine specific, but these 2 are a good place to start.