B16A1 (although I don't believe there really is an A1, thats just what people call the first gen B16) is just the 1st generation B16. It was OBD-0. I think the only real difference between that an a B16A2 is that that is OBD-I and has like 10 more hp.

However for you it doesn't bolt right up into the '84 CRX. You will need to buy custom mounts (they might make them for that swap, I'm not sure) and a custom linkage to at least get it in the car. Then wiring. Is your '84 Carb or Fuel Injected. If it is Carb then that already makes it more trouble than its worth for the swap I think. There are other Carbed Honda engines that fit into your car. If it is Fuel Injection than you can do the B16A easier, also if you want a cheaper alternative I believe the D16A1 bolts right into the 1st gen CRX.