> Thank you for posting this, it reaffirms what I've been thinking for so long. There are many opportunities to retrofit old systems of all types with modern low-cost embedded technologies.

At my shooting range, where security is very important, we're replacing the old antiquated "fire stop" (when everybody on "shared" lanes has to stop shooting for there's at least one person going to change the targets) system with a modern system of electro-magnets and embedded devices. Mechanical safeguards where, by default, the 10 lanes (there two times 10 lanes, the 50 meters ones and the 100 meters ones) have to stop shooting and then an embedded system with a little controller for each lane that needs to be working to give the greenlight / "fire frei" ("free to shoot").

We mostly decided on the switch after a failure of the old system: the "free to shoot" system has recently been given even though there was still one person outside, changing the targets (nothing bad happened but this is a serious incident).

We asked for quotes for a system that is always "door locked" / red light / "fire stop", unless everything works fine and every lane gives the greenlight (each shooter has now one badge).

Same thing as in TFA: cost in hardware is minimal compared to the quoted prices. Like basically 1/50th of the quoted price.