Yes thats correct.. dot3 is simply an instruction that has been implemented in the fixed function pipeline.. the dot product is the basis for the bump mapping effect..i dont quite understand the maths but it manipulates the matrices to approximate lighting effects from a normal map. GeForce 2 has the dot3 instruction..but since it doesnt have pixel shader support, you cant do as Ventilator has said.. so.. the standard bump mapping looks fine as long as you use a constant light vector.. as soon as you change it it will get messed up. Also it doesnt allow for the per-pixel lighting.. without which bump mapping is underwhelming anyway.