I moved the project to EP4CE6E22C8N Cyclone IV chip
So now my CPU has 4 registers A0 to A3, 2 auxiliary registers B0 to B1.
The system has 8K ROM, 16K RAM and 8K video ram
and the video controller supports 300X208 pixels, 50x26 characters
I started writing a short CPU function and instructions description here.