Weird alarms in school

Hi! This is my first post here, I just thought it would be cool to share this really odd setup I documented at my old high school.
I’ve created an Imgur album with the photos I have, and each photo has a caption explaining it.
HOWEVER, I have seen some warnings on this forum that younger members might not want to visit the link, as I can’t predict what else you might see. View with caution!
http://imgur.com/a/eWUF8
If you’ve read through those captions, I have some additional points:
Every pull station is a BG-12. Didn’t feel the need to document those.
I have also seen some SpectrAlert Classics, Simplex 490X-9219s.
There are a few bells on the exterior, but they are all disconnected.
Every classroom has an alarm, but what alarm it is seems to be random for some reason.
ALL of the non-bell alarms go off for a fire drill, it’s probably the worst symphony you’ve ever heard.
There are tons of SpectrAlert Advance alarms, adding ones where a recent law change required them and replacing “dead zones”.
The cafeteria has SpectrAlert Advance voice evacs after a recent remodel, but the old suppression system is still intact.
Oh, nothing is synced. the Advances are set to Code 3 and everything else is continuous.

I’m not really a fire alarm guy, but I am interested and came here through NewAgeServer’s stuff on youtube. If you’d like to figure out what alarms are pictured, go ahead! I’ll try and answer any questions about the system, and snap more pictures if you want.