The POKEs listed in the Applesoft Reference manual allow you to plot data on one High-Res screen while displaying the other.
The POKEs control which screen is displayed, while location 230 (decimal) controls which screen is plotted by the HIR =>ommands. For example, POKE 230,32 causes Applesoft to draw on screen 1 (HGR), while POKE 230,64 will draw to screen 2 (HGR2).