Just two days ago I was reading a discussion, here on HN, about early days of programming and someone in the comments mentioned that games like PONG were easily

Just two days ago I was reading a discussion, here on HN, about early days of programming and someone in the comments mentioned that games like PONG were easily moddable, and you could change a lot of variables because they used diode matrix. Lo and behold, today 'diode matrix' is on the first page. :)