Last week, I have been toying with Hercules, a "mainframe" emulator for Windows and Linux. Within Hercules, one can install different mainframe OSses, such as MVS, VM/370 or Linux/S390. Different older IBM mainframe OSses can be downloaded from cbttape.org. It looked promising to run VM on my laptop, but alas, the VM/370 version there is arcane. You won't find utilities like FILELIST or XEDIT, which makes it almost useless. A bit of a shame : it's hard to believe that IBM won't provide a modern VM OS to tinker with. It could attract lots of new administrators and developpers.