not sure if this is a bug in picotron or just in the docs, but in the gfx pipeline doc it says that the colour tables are accessed like this:

out_col = peek(0x8000+coltab*0x1000 + target_col*64 + draw_col)

but to get the colour table working properly in practice i have to swap the target and draw colours like this:

function c_set_table (draw_color, target_color, result)
  poke (0x8000 + 64 * draw_color + target_color, result)
end