Pinball machine restored with Arduino

[@DandyDon1]

Did the original controller board have firmware/software which loaded upon start up, is it strictly run by the 74164 8 BIT SIPO shift register ICs?

[@DandyDon1]

BTW Digi-Key currently has the National Semiconductor SN74LS164N (substitute) for the 74164 at $1.00 each. That is if you ever want to experiment with repair of the original controller board.... :o)

[@electricpiano5k]

Hi, the firmware ran directly from read-only memory. It was one of the ROM chips (6520) that was dead.