Changes
/* On MiST version */
Can look after a old NEXYS4 version, perhaps the first ones doesn't has "internal mirror VRAM", but a clk sequencer in external RAM.
=> do try another VRAM double buffer bank, in simple_GateArrayInterrupt.vhd do play with :crtc_A_mem(14 downto 0):=MA(13 downto 12) & RA(2 downto 0) & MA(9 downto 0);crtc_A(14 downto 0)<=crtc_A_mem(13 downto 0) & tic; <= shall be crtc_A(15 downto 0) be here...
Do check the VRAM write speed also : is still a screen written at 50/60Hz ? do check vertical_counter/horizontal_counter scan related to that.
