[CrazyStat]

A connecting line there means that that the data from that memory location can be stored in that cache line. In the fully associative cache any memory location can use any cache line. In the direct-mapped cache each memory location has one designated cache line it must use (but each cache line has multiple main memory locations associated with it).

[flumpcakes]

This has been a very helpful and explained very clearly and directly. Thank you. I'm having trouble keeping up with some of the comments in this thread but this one has been very illuminating.