i've tried his robotron sources. It's either unfinished or non-working. There is no project files for specific board. Only make files for simulation. All vhdl files are converted to verilog with unknown state (may be it's just POC). I've spent a lot of time to combine the set of separate files with pretty weird rom presentation. All in-vain. It doesn't work. I don't want to touch other his cores - probably they are in the same condition.
Another big problem with sources originally written in Xilinx environment is that fact Xilinx allows to compile pretty bad unreal constructions. And some devs actively use it. Multi-drivers, multi-clocks - all this is possible in Xilinx tools. And only crazy Xilinx developers know how it even possible to compile.
And when i try to port it to Altera - i have to deal with all these mad constructions. To fix it, i have to know how exactly it supposed to work which is not always obvious. This may take a lot of time..
P.S.: that's why i didn't port for example Mega65, although i've tried it hard...