I likewise really miss that. Some early USB drives actually had those too, but it's been a really long time since I've seen one.

Big SD cards also have a physical switch that enables readonly mode, although I don't know if it's the reader firmware which disallows write requests, or simply the software driver needs to support it.

A bunch of my SD cards have a write protect slider on them.

Also one of the SD/microSD adapters in my drawer has it.

Apparently the write protection on SD cards is entirely optional and only enforced on the drive/reader side. The reader can just choose to ignore it and allow you to write to the card willy-nilly: https://electronics.stackexchange.com/questions/325868/how-d...

And apparently is common for them to be ignored: https://superuser.com/questions/1737227/is-it-now-typical-fo...

Floppy drives are the same. Though maybe more commonly respected.

SD spec has write protection (not the sliding switch). Protection can be temporary (resettable via a command) and permanent (not resettable). A write protected SD card will ignore write commands from the host. Curiously, most OSs do not seem to check for this, and will pretend the writes work and then be surprised when they did not (eg: Windows, Linux).

For anyone curious: https://github.com/BertoldVdb/sdtool is a tool to for that. I may or may not have bricked a card while toying around with in on a Pi :)

Do you mean brick because you turned on permanent write protection (and it worked) or do you mean the card just completely died for unknown reasons?

It turned on write protection. It was a while ago, so I don’t remember exactly, but things got weird as the OS assumed writes got persisted while in reality they just got completely ignored. Was a fun experiment.