OK, don't laugh.

How do I know what ECU I have? I know my CRX has a B16a and I found the ECU located under the passanger floormat but I'm not sure what type of ECU it is or what car it came out of. If I pull the ECU codes from it (my cel light is on), does it matter what car the ECU actually came out of? Will the codes be valid?

I was told when I bought the car that the engine was a '92 teg but I'm not positive. I really need to find out for sure before I have to start fixin' and replacin' things!!