I'm a software programmer with a lot of experience working with older technology but never with such constraint. I've never done assembly programming so I plan to see what I can make out of the z80dk toolkit which seems pretty robust.
I've since gotten myself a few TS-1000s to tinker with, some tapes, and a cassette deck. I'm also interested in the Spectrum but think it will be more fun to take things slow. I also bought a TC-2048 for enjoyment but I'm going to save that for later! I know that I'm going to quickly outgrow the limitations of the TS-1000 so I plan to modify these to allow high-res graphics routines; which is why I bought a few units in case I break something.
Looking forward to sharing my experience with the rest of you.