Darrggg I had a really big comment otherwise....
The SMS is a 16-bit system from foot to toe. Think of it like the SNES which is really a lesser 32-bit system.
Here, let me settle this once and for all. the Sega Master System uses an
8-bit Zilog Z80 as it's CPU. The same CPU used in the SG-1000, ColecoVision, Game Gear, Game Boy, Amstrad CPC, MSX, TRS-80, ZX Spectrum and dozens of others. While no where even close to having the power of a 16 bit system, it was used in the Genesis/Mega Drive as a co-processor for audio, think of it as a "little helper" in the Genesis nothing more.
To touch on an earlier comment, the SNES is not a "lesser 32-bit system". Most of the games that were innovative in graphics or physics or sound, had custom made chips added into the cartridges to assist the unit's capabilities. There's over a dozen different types of custom chips that were added to carts, they made games like Starfox, Super Mario RPG, Mario Kart, Doom, Pilotwings, Mega Man X etc. possible. No different in function than say a 32x or the SVP chip that was added to the Genesis version of Virtua Racing.
That doesn't make the system more than what it is, no more than a 512 meg vid card matched with 512 ram give you a 1gig desktop.