The only way to get coins to credit as you are asking is to use an SP1137 game chip. This allows a few different styles of playing including tokenization of each coin. I have a 3CM Triple Diamond that I have set the token value of each coin to 99. That is the most allowed. The settings are 1 to 99. So each quarter dropped in registers 99 credits. This particular chip also has a repeat bet function. Whatever your last bet was it will repeat by pushing the spin reels, play max or even pulling the arm. The arm solenoid is energized all the time to repeat as wanted. If you only want to play 1 credit, push the credit button once. Those same features will work then with only one credit played.
Dave