The I/O boards in the game must be configured in windows to be on COM port 1 for the I/O board located in door 3, and COM port 2 for the I/O board located in door 6. If the computer cannot communicate on the comports all tombstones will flash yellow and the bonus display will be blank and you will not be able to coin the game up. You can check if your computer and the I/O board are communicating by looking on the main screen of the game at the very bottom. When there is no communication after the I/O board number there will be two dashes (--) , when communication is established the version of software the I/O board will be displayed after the I/O board numbers.
No Communication Communication to I/O#1
Communication ports are configured in the windows device manager steps to access the device manager and change the COM ports are listed in the PDF below.