1) This machines has a large board on top of the mainboard - this board plugs into the Z80 socket (the Z80 moves to the top board), as well as a ROM socket and the monitor connector - there is also a bunch of "flying leads" which connect to various points on the mainboard and attach to a socket/header on the top board... Can anyone tell me what this board is? Is it "normal" on an Osborne-1? Neither of my 1A's have this board, and the mainboard appears to be the same... Is it perhaps an upgrade of some kind? 2) Has anyone disassembled or otherwise obtained source code to the Osborne boot ROM - I would like to try and figure out how far the machine is getting, and what it is doing when it restarts. 3) Has anyone seen this behaviour in an Osborne before?