Way back in the day, I tricked f'd Canadian parking meters with US quarters. Exact diameter. Or close enough. This was when they were like wind up clocks. The parking meters. They actually had to wind them. Not a big deal... washers worked down here. I mean the kind you buy at Ace hardware. God I miss the good ol' days. Not that I would do that now.... we're talking 30 years ago... but whatever. There was a certain washer that worked perfectly as a nickel.
More importantly, these guys had to create their own trading platform. I remember from the book it was over a million lines of C++ code. Man, that is incredible. Today, we have the luxury of having these powerful platforms already built like Ninja Trader, Multicharts, Sierra, Think or Swim, etc.