i found a mod chip at robwebb.clara.co.uk that arrived in the mail today. It has inputs for both a 20 pin Saturn as well as a 21 pin version. It also comes with an extra cable. Here is a pic: [attachmentid=1445] I thought this information might help those who own the older models of the system. If anyone has already installed one of these before, please post here to let me or anyone else gain a better understanding of what the exact process is. I have a basic idea, but do not yet know for sure which cable is for the input, and for the output one(there was no instructions included). There is is also a wire that needs to be connected from the chip to a +5 volt power source somewhere inside the Saturn, and I will experiment based on some info I saw in another post: http://forums.segaxtreme.net/index.php?showtopic=16264&st=15 and repost when I see some results. edit: here is the picture from the other forum which shows a lot more detail than mine. edit2: whoops! thanks to dj898 for letting me know it was his photo I posted [attachmentid=1444] Notice on the top right corner of the chip the words "20 pin". It also says IN and OUT above each of the 2 sockets, though the words are blocked in this photo. The 2 sockets on the left side of the chip are labeled the same, but with "21 pin" text printed. So I assume this chip is suitable for both types of machine. On the bottom-right of the chip, where it says "+5V", I am guessing that a wire will be soldered at this point on the reverse side of the chip (where the actual solder joint is located) and then the other end of this wire is soldered to a suitable +5 Volt source which is probably the red wire that is connected to a white plug/harness located on the front right hand side of the machine's circuit board(it's the only one-you can't miss it). In the other topic post I linked above, the person C-S-B claims that it is possible to verify that the red wire is indeed the +5 volt power source by removing the small circuit board that is attached to the top half of the Saturn, and checking the labeling on the wire. If in the event that this isn't the case, or your system is different, the voltage of the wire should probably be tested with a multimeter first to make sure that it is indeed +5 volts there, because I have read posts from people who have had numerous problems installing mod chips and not knowing where they went wrong. Now I just have to figure out which cable goes to the "IN" slot, and which to the "OUT", and then if it works, I'll repost with some sort of a guide.