>> Oh, Simon, I think >> I found the way to distinguish DECsystem 5900 from 2{4,6}0. > > And? :-) :-) Do you have any chance to check a certain bit (0x8000) of IOASIC INTR register on 2{4,6}0 and DECsystem5900 after boot? Tohru Nishimura Information Technology Centre Nara Institute of Science and Technology