I have a Mega168, so yeah 1k worth of RAM. that should be plenty. All I use except the frame buffer are a few int counters for looping (all in functions so they are all released fast). To my calculations, 21x16 would be 336 bytes, which is way under. Now boosting the resolution to just 24x18 (432 bytes... still plenty of room left) and the uC crashes. AS for your idea of packing more pixels per byte, yeah that's a great idea... definitely something I'll look into today.