A while ago I convinced myself that the 5200 mainboard could be reduced to the size of a game cartridge, but still using the original 40DIP ICs and DIP ROM. Last Fall, I gave it a try. Family obligations and the dread of soldering small SMT components put the project on the back burner until a couple of days ago.   It works wonderfully! The mainboard measures 88mm x 108mm and features audio line out and svideo out. Here it is in comparison with a 5200 cartridge. And with an Atarimax USB flash