Slot info?

Anywhere I can find info on how slot machines work? I've read some stuff and have a pretty good idea but I see posts on here about games being a "1A/something game" (totally made up, I'm sure you guys know what I mean) and I'd like to figure out what that means.
I'm not much of a slot player, but I've been taking my 92 year old Dad to the casino 3 times a week now and I play a little, and am interested in finding out how they work and what the differences of various machines are.
I'll search this site for more info, but wondering if there's somewhere I can find it all in one place?

Google slot math is fun.

I think you mean class II and class III, bingo slots and Vegas slots, respectively.

That depends on what kind of slot are you talking about. Their is the old mechanical type that was used on the early days of casinos. Their is the new slot machine were computer program calculate what should be the result.