I hope you never have to work with serial D9 cables. The variation of pinouts for legacy equipment is massive! Pretty sure every theoretical variation became some standard.

Hah there was one on the 8088 I was allowed to play with as a child, but I only used the parallel port to switch on/off a motor via a relay.

Better to learn from my experience than yours.

Right? And people say assembling a PC is just like LEGO!

I'm lucky so far that I've kept all the cables from all the PSUs I've had, and they matched in colour per PSU, so I've never had the temptation to pick a random one. Phew, saved by autism.