old DEC software

For the most part, no software is available because DEC/Compaq/HP hasn't given permission for redistribution (other than the implicit one in your being allowed to borrow someone's VMS set with a valid Hobbyist license). The rumors I've heard indicate that OSF/1-DIGITAL Unix-Tru64 is "encumbered" and so is unlikely to ever be freely released. The GossipNet indicates that this (encumberances and royalty payments) is why the "Enthusiast" license is $100 instead of the VMS program's $0 (or $30 if you want the disk). Sadly, Alpha died at the end of October and the enthusiast Tru64 program likely died with it. Ultrix seems to be a slippery beast, though, and pops up from time to time on the Internet, in both VAX and MIPS forms- look around.