You can convert a non-working compact Mac into a Macquarium.
Except for memory, it’s the same as the 128K. There’s really not a lot more you can say about the “Fat Mac” than that. This made it possible to work with larger files, more powerful software, and have more files open (running more than one application was still in the future, awaiting MultiFinder). Introduced to replace the Mac 128K in September 1984, the 512K had four times the RAM of the original Mac.