Just to nitpick, in the section after "On the other side, these following guards are more of a “you really shouldn’t do this” variety – much closer to a disabled state in graphical user interfaces:"
The second and third examples are safety lockouts [0] working as intended: Some system is locked in the off state to ensure safe access for technicians.
Especially the padlock lockout is simple and effective: As long as you have the key in your pocket, you can be sure than no one is going to turn on the meat grinder you are cleaning.
The STOP and RESET buttons are from a Documation card reader.[1] They're not guarded. They just come from a standard kit of buttons and lamps where you could assemble the components and dividers into a control panel. That style of illuminated push button was once popular and is still available.[2] NASA Mission Control consoles had lots of them.
The hover images were delightful thank you for that little bit of whimsy. Also the iTunes Burn CD one was my favorite! I totally forgot about that and its so fun compared to flat design.
Yeah, it’s funny how IBM managed to be both absolutely undeniably corporate and somehow still incredibly beautiful. I think it’s just a testament to the visual pleasure created by knowing someone really truly cared about what they were doing.
I fully expected the origin of "Molly Guard" to be apocryphal, akin to something your boomer uncle sends you in 2008, that's been forwarded 1000 times and you can see all the fwd: address lists in the message ("Hey Susan, thought you might find this funny... -Bill"). I was not expecting to see the actual Molly in an archived newspaper article. Pretty cool.
The second and third examples are safety lockouts [0] working as intended: Some system is locked in the off state to ensure safe access for technicians.
Especially the padlock lockout is simple and effective: As long as you have the key in your pocket, you can be sure than no one is going to turn on the meat grinder you are cleaning.
[0]: https://en.wikipedia.org/wiki/Lockout%E2%80%93tagout
Creators of some keyboards placing a sleep button right above arrow keys didn't bother doing this.
[1] https://www.youtube.com/watch?v=se0F1bLfFKY
[2] https://cpc.farnell.com/rjs-electronics/rjs-k16-391-ge-65j/i...