I wouldn't be able to help with the more modern stuff but given DCPU-16 is designed to be an 80s-era CPU it suits my experience quite well :-)

I'm not really looking to learn as a means to expand my field of working expertise but more for the sake of it. My programming experience has been firmly rooted in higher level languages and I think this is a perfect opportunity to learn something new and potentially useful. I don't like the idea of having the lower levels of programming remain a black box as such

You might be interested in py4fun - it has a fairly light weight introduction to a "mythical machine", including assembler and compiler: http://openbookproject.net/py4fun/