Is that what that short slot is for? I've long wondered. The two SIMMs are both RAM. I'd forgotten that one slot is offset like that. Max ram is 52MB with 4MB soldered, one 16MB single sided, and one 32MB double sided module. The slot at the bottom of the image is the video connector.

Thanks for the info. Some of my memories of these things are returning.

Here's a fun project page: http://www.mactech.com/2004/06/03/project-black-mac-lc5500225