These machines were in use in Japan for over decades and have gone through a few developments as well. Over the last years, the Americans have warmed up to this new kind of slot japanese pachislo slot machine and Pachislos can increasingly be found in American casinos these days. A Pachislo slot machine, on the other hand, is a skill stop game and there are no bars to casinos storing them as gambling machines.
In case of coins, the pachislo machines accept tokens and you can change those tokens into money over the casino counter. Machines generally come with three slots and if you can pull off a single set of numbers or symbols in all the three slots, you win a pre-allotted number of tokens. There is a toggle or button for each of the slots and as you push the button the reel goes off spinning and you can stop the reel by pushing on the button again.
The game is called skill stop since it adds the element of skill to the slots. However, you have to practice it hard and master it thoroughly to achieve any kind of perfection regarding stopping the reel at your required number or symbol.