From the "Mainframe Enthusiasts" Discord; I don't have any other contact for him but I can send you a link to the Discord if you can't get there yourself. This is one of the first (maybe the first) of the 64-bit zSeries (descendant of S/360, S/370, S/390) machines. You would have to pay IBM a lot of money to legally run a modern z/OS or MVS or VM or z/VM or VSE or z/VSE on it (and current versions won't work, but, like, z/VM 4.4 would). You could run MUSIC/SP for free, and of course VM/370 and MVS 3.8 are in the public domain (although I do not know offhand if the z9 can run those late-70s OSes). It will also run S/390 and z/Linux of the right vintage, which are free but maybe difficult to acquire these days.
From Member @Booper : Z9 mainframe, ds8000 storage array , tape drive and misc components are scheduled to go to scrap at the end of the month. If someone wants to chime in and throw some money my way, i can sign the whole storage unit over to you. Located in melbourne fl.
