Explanation from olivieryuyu:
1. I do believe that RS ucode has no lighting as I cannot see any code for it! I guess that it was done on the purpose to save power for other matters.
2. G_TEXTURE (command BB) does not set the texture s and t scale. Command BB is composed of two 32 bits words (as for FAST3D) but RS ucode does not use the 2nd 32 bits word. This latter seems to be always nil and should be considered as padding.
3. Movemen (command 0x03) case 82 does not concern light (because there is no light!!!). Actually this case of movemen seems to set the texture s and t scale which is then retrieved by the B4 command and combined with the texture coordinates.
