Oh, and about speed. Seems there is no need in frameskipping. Really slow part is z80 core emulation
So, what to do with scrolling. Why it repeated 8x times?
(i tried to add counter in video draw, which allow only each 8 line to be draw - but no good)
if in background_y=((y*8)+(256-scroll_reg))%256;
you change y*8 to y*16 it will repeated 16 times, but if you make y*1 it will repeated forever (i.e. only one tile will be draw/scrool at all screen)
So, what to do with scrolling. Why it repeated 8x times?
(i tried to add counter in video draw, which allow only each 8 line to be draw - but no good)
if in background_y=((y*8)+(256-scroll_reg))%256;
you change y*8 to y*16 it will repeated 16 times, but if you make y*1 it will repeated forever (i.e. only one tile will be draw/scrool at all screen)