Theres a Dosh N Pecks in the bookies
It isn't the RAM of the fruit machine that is read, it is the ROM from the program card. Most machines have at least 2 ROM chips, say one for Game and one for Sound Samples.
They are ripped using a ROM reader, you basically plug the chip into it, and dump the contents onto a PC. You then run the ROM through the Emulator. The machines on here use the actual pub ROMs, but stuff like the Software Illusions machines use their own program code.
To be honest, considering they are started from scratch, those machines from Software Illusions are not bad at all, and before FME came about, they were the closest you would get to having an English pub bandit on the PC [except for maybe a couple of other sims, but they were still a very good compromise].