BillyHW, on Wed May 16, 2012 8:38 AM, said:
Sega managed to include an entire SMS inside the Genesis, and it always sold for less than the SNES. Nintendo could have done it for even cheaper if the CPU was backward compatible. Even an adaptor like the Super Game Boy would have shut some complainers up.
Of course Sega made you pay extra for the cartridge slot. (And the card slot that like a dozen games used.) At least it ran almost all of the games, except the F-16 card, which used a TMS9918 video mode.
I have a Tri-Star module, but I'm pretty sure it's just a NoaC Famiclone, and doesn't use the SNES CPU.
Remember that the '816 is based on the 65C02 instruction set. I wonder if any NES games used the 6502 "undocumented" instructions? There's no BC that could fix that! At least by that time, everybody would have known about the 65C02 and would probably avoid them.
Basically, here are the main points:
* CPU needs to be BC. 65816 will run 65C02 but not 6502 undocumented instructions
* Cartridge slot needs to be BC. The 7800 did that well. The NES had that awful metric-spaced toaster piece of crap. The toaster part could be removed, but the metric spacing was uncool.
* Video chip needs to be BC. It needs to support the same video modes, and, oh wait, the NES has that dual bus in its cartridges, right?
Yeah, that would have been the sticky point. To keep BC with NES games, you would have to have the video chip bus in the cartridge, which clearly wasn't worth the extra cost in the SNES. The SMS had a standard one-bus cartridge, and it was pretty easy to just put a multiplexer in the chipset.
So basically, they would have had to go way out of their way to make the graphics ROMs in NES carts work, which means a lot of extra cost. I guess that's another thing to add to my list of bad things about the NES hardware design.