There was actually not much need of drivers or firmware. 3Dfx products had a very simple and straight forward way to write commands directly to registers [1][2]

There was actually not much need of drivers or firmware. 3Dfx products had a very simple and straight forward way to write commands directly to registers [1][2][3]. 1.: https://web.archive.org/web/20180220234020/https://www.openglsuperbible.com/2013/09/07/voodoo-registers-part-1/ https://web.archive.org/web/20180220234020/https://www.openg... 2.: https://web.archive.org/web/20180629191415/http://www.openglsuperbible.com/2013/09/18/voodoo-registers-part-2/ https://web.archive.org/web/20180629191415/http://www.opengl... 3.: https://web.archive.org/web/20180628125330/http://www.openglsuperbible.com/2013/10/21/voodoo-registers-part-3/ https://web.archive.org/web/20180628125330/http://www.opengl...