What the old/new pins are for are the diffrent lasers that came with 21 pin models. If the casing has round buttons it's a 21/new. if the casing has oval buttons it's either a 20 or 21/old.
It's irrelivant though because gamegizmo's saturn chips come presoldered to the "old" laser setting, and it works just fine with new lasers in that mode (I know it dosen't make much sense but just trust me).
I have to warn you that their chips arent always great quality. I ordered one overnight on july 30th and when it came it was doa. The system wouldnt boot with it installed and the chip started smoking. Wierdest thing I've ever seen with a mod. I returned it and it took them until two days ago to get me a replacement chip, although they were nice enough to send me two fully functional chips to replace the one I ordered. Anyone wanna buy my extra chip?