As the story goes the NES 101 (top loader) was made way after the game genie was invented. And as a either design over sight or with purposeful miscalculation (Nintendo didn't really like the game genie). A game genie will NOT fit into the top loading NES.
Now this was realized this and sold a adapter to use the game genie , it was free if you asked for it, now they are very very rare.
And one is now being sold on ebay for more then a hundred dollars.
And i am not going to pay that much to mess around with some Nintendo games. So i for a way to hack the game genie to fit into the top loading Nintendo Entertainment System.