Same CPU (different clock speed) and similar sound chips. But, most of the "magic" happens in the graphics chips, which are fairly different. I've been taking

Same CPU (different clock speed) and similar sound chips. But, most of the "magic" happens in the graphics chips, which are fairly different. I've been taking my first baby steps into Genesis/Mega Drive development. On a line-by-line, cycle-by-cycle basis, the experience is one of feeding the VDP (its graphics chip) ...keeping it happy, and managing its quirks. Interestingly, while the Genesis/Mega Drive is obviously far less powerful overall than the NeoGeo, it's more flexible in a few ways. They're not the most useful or spectacular but you can do some tricks that are impossible on the NeoGeo like a limited kinds alpha transparency. You can do it directly with shadow/highlight mode, or convincingly fake it with kind of a "stencil" method.