Here is a project a couple of years in the making, but Im almost there I hope. I have completed the basic input /output controller based on an Arduino, I am still working out a few details so here it is for review

 

I thought maybe I needed to elaborate more on what I am doing, this schematic will eventually control the input and output of a pinball playfield when it is built (the controller that is, I have the playfield already complete). The input is handled through 6 4021 ic's, the feature lights and flashers are handled by a MAX7221 ic, and the solenoids (or in my case 12vdc liner actuators) are handled by 2 4094 ic's.

I suspect that my newbness is going to lead to a few errors but I feel pretty confident I got most of it right, Im thinking about switching the MAX ic to the spi port but was trying to find a way to flip all the input and output to I2C, I believe this might add more speed to the project as well as reduce the pin count that I am currently using.

I intentionally left the RX and TX ports open to interface another Arduino for the instructions and maybe the sound as well, but that is still in the thinking about it phase