The DE0 Nano looks a little heavy. I don't think I have any need for a hard processor.
The mercury's form factor looks very appealing - not sure about having one gnd pin. I have no experience with this so I go with what is said here. The highest frequency will be the clock that drives the FPGA (logic) which drives the transfer mechanism to output the video.
The board would need at least 16+8+4 IO lines for accessing the external video ram (forgot to mention this earlier). The rest of the remaining IO I will probably use for address decoding etc. (although I wanted to make the design modular...)
I would not mind buying a dev board with a larger/heavier FPGA than I need right now, IF I can down-scale the design to something smaller and compatible (and what will be compatible?).
Looking at the Altera site the MAX10 looks pretty good - haven't studied it yet in detail. Not sure about the packages it comes in though.
Would that be something that is suitable to start with as a beginner?
Another thing occurred to me: Because the exact FPGA is not too critical, would it stand to reason to let the quality of the tools dictate what brand I choose? In that case which brands have the best tools?
@daybyter: sorry I couldn't decipher your hint on the zx81 version of the Cyclone II on ebay? Could you be more specific. Is it ZX81 programmed into a Cyclone? - that is not what I need.
Thanx for the suggestions.