High Quality Content by WIKIPEDIA articles! The Radeon R420 core from ATI Technologies was the company`s basis for its 3rd-generation DirectX 9.0/OpenGL 2.0-capable graphics cards. Used first on the Radeon X800, R420 was produced on a 0.13 micrometer (130 nm) low-K process and used GDDR-3 memory. The chip was designed for AGP.