How would I program a coin acceptor?(raspberry pi)

Guys, can you please help me? I have the same problem as Tony Forbes and none of the answers above really solve it.

I have a working coin acceptor thing (3 of them actually, but one fits where I want it better so I'd prefer to use that if possible) from an old pub gambling machine like Peter Oakes suggested getting.

My problem is that I have no idea how to physically connect it to my raspberry pi and absolutely no idea how to program it to work with the games.

I have got some ROMs where there are 'credits' built in (arcade versions of games basically), but atm I just press 1 or 5 to add credits. How do I make it so that adding coins in the coin slot works with the ROM and is the only to add credits? The fact that you can use the keyboard atm shouldn't be a problem since I'm building an arcade machine and I don't plan on attaching a keyboard (except when modifying it).

I'm really stuck on this at the moment, so any help would be greatly appreciated.

Thanks in advance.

Guys, can you please help me? I have the same problem as Tony Forbes and none of the answers above really solve it.

I have a working coin acceptor thing (3 of them actually, but one fits where I want it better so I'd prefer to use that if possible) from an old pub gambling machine like Peter Oakes suggested getting.

My problem is that I have no idea how to physically connect it to my raspberry pi and absolutely no idea how to program it to work with the games.

I have got some ROMs where there are 'credits' built in (arcade versions of games basically), but atm I just press 1 or 5 to add credits. How do I make it so that adding coins in the coin slot works with the ROM and is the only to add credits? The fact that you can use the keyboard atm shouldn't be a problem since I'm building an arcade machine and I don't plan on attaching a keyboard (except when modifying it).

I'm really stuck on this at the moment, so any help would be greatly appreciated.

Thanks in advance.

This is a purly speculative answer but...

1. For the PI, you can react to a GPIO pin and inject a character (5, or 1) into the keyboard stream, i'm sure there are plenty of examples on how to do this. and it would be easy to test and simply adding a switch with pull up (Pull Up can be programmed) to the gpio would be enough to test

For the coin acceptor, it depends on what it outputs when a coin is accepted and if it is a pulse output you can feed it through an opto isolator to the GPIO pin used in the above test (Switch) and away you go. If it is from an old vending machine I doubt it will be 3V3 compatible, therefor the need for the opto isolator