It was a DIP setting on the board, so it would be up to the arcade operator to set it. Many old arcade games had difficulty and pricing and other settings that could be changed by the operator with either DIP switches or built in menus to update CMOS settings.
I remember being able to just about 1cc a NeoGeo soccer game (Super Sidekicks) in my local arcade only to come in one day and be dumbfounded when I suddenly couldn't even win the first game.
Sorry, lapsed into gaming vernacular there. One credit complete, finishing the game on a single coin, i.e. because you don't lose you don't have to pay for any continues. So, for the game in question, one coin would get me all the way through to the World Cup final.
(Modern games got wise to people getting too good and some only offer a single play per coin, win or lose.)
If you read the article, there is a lot more going on then a simple hex dump. Digging through schematics, and finding the bonus time dip switch, to actually get it triggered is the key bit here.
