Good work for a first try, though it needs improving for faster loading-unloading. It is quite buggy when you try to spark it in fast succession. Probably because of the water timing. Also, it should be READ not WRITE.
After some testing, inputing 0010 = 0000. Very buggy indeed.
i'm trying to make them smaller but seeing as the 2/10 version is almost 4 times larger and can only hold 6 more sparks then the 2/4 version that doesn't seem to be going to happen any time soon.