This is a little bit faster (screen 13):
def seg = &hA000
poke 320 * y + x, color
replace x and y with your x and why coordinates, and replace color with the number of the color you want.
For hi-res graphics, see the topic: Screen 9
: Does anyone know anyone fast versions of PSET?
: Can someone tell me how to make the graphics 1024 * 720 instead of 640 * 480 or 320 * 200? (Infact, anything higher than 800 * 600 would be nice).