Console graphics came from bespoke, fixed-function chips for more than two decades, until the original Xbox burst onto the scene in 2001 with a PC GPU inside. Those of us who played on early consoles like the NES will have come across some familiar quirks with those fixed-function chips: When too many Goombas lined up on the same row in Super Mario Bros., for example, some of them would start to flicker. That's the NES's graphics chip hitting its hard limit of eight sprites per scanline; the chip drops anything past eight, and the game alternates which ones.

In the NES, it was the Ricoh 2C02 Picture Processing Unit that rendered game graphics. A pretty rudimentary chip, it couldn't run any code. Instead, it took tile artwork from the cartridge and a couple of lookup tables from memory and turned them into a TV signal, one scanline at a time. That arrangement — a dedicated picture generator fed by the CPU — is how most consoles rendered their graphics from the late 1970s into the 2000s.

When Microsoft's first Xbox came out in November 2001, it didn't look much like any console before it. Instead, it was built around an Intel Pentium III and a graphics chip NVIDIA made specially for it, based on the GeForce 3. The GeForce 3 had only been announced that February, and it was the first GPU that let developers program their own pixel and vertex shaders.

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