[tyingq]

At a high level, I suppose, but for example...3.8j is 24 bit versus the current z/os 64 bit.

[bigato]

Indeed the last official MVS freely available is 24 bit, but then you have stuff like MVS380, which supports 31 bit and has 64 bit support in the works.

http://mvs380.sourceforge.net/

[bluecmd]

Indeed, the 16 MiB virtual memory space is kind of limiting for anything remotely modern :-).

[_lwad]

It teaches efficiency to learn the basics on such a system, something modern programmers are often lacking