For those wondering. Gradius was the first game to use the Konami code.
According to legend, it was implemented by a programmer who was trying to debug the game and having a hard time playtesting because he wasn't very good at it, so he added an "obscure sequence of inputs" that would give him all the weapons so he could survive long enough to test it, and supposedly, nobody bothered to remove the code from the final version.
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