It's such a damn shame that IBM makes all of this stuff utterly inaccessible to the developer, hobbyist, and academic crowds. In the past few years I've taken

It's such a damn shame that IBM makes all of this stuff utterly inaccessible to the developer, hobbyist, and academic crowds. In the past few years I've taken an interest in big-iron systems, and I've recently started spending time with OpenVMS in preparation for release of the x64 port. I spent a lot of time digging into System i, and z/OS, but my efforts were constantly frustrated by the inability to get my hands on real software and/or hardware, or even paid time on a machine. Shoutout for the OpenVMS hobbyist program. Anyone interested in obscure commercial OS's with serious pedigree should give it a look. HPE's OpenVMS documentation portal is well laid out and straightforward - all the information is there.