To run one of these, you need a second board with memory, there is no RAM on the main board. I typically use a 16M ECC memory board and run the two boards in an old sun 3/110 case.
Mine has been sitting for about 10 years gathering dust. I recently got interested in it, because I was working on a disassembly of the Sun 3/60 bootrom. These Sun 3 roms have a lot in common and I felt it might be helpful to actual run one and poke at it. I also have a growing interest in booting and running code.
Tom's Computer Info / tom@mmto.org