As it looks like that my MPU replacement for Williams System3 .. 7 games 'WillFA7' is working now https://lisy.dev/willfa7.html
I'm starting to gather information about Williams System11 games for my next project 'WillFA11'

The goal is to be able to replace Williams MPUs for SYS9,11a,b,c & Data East MPUs
I had a look to different Manuals, pinwiki, forum threads, ... but I'm still unsure on a couple of things

1)
connector 1J9 'Opto row', used for seperate row for opto switches?
I saw this connector only populated on SYS9 & early SYS11 MPUs.
Which games would need this connector and what are the difference to the 'normal' switch rows?

2)
connector 1J21 'Widget IO'. Usually used for background soundboard?
I saw that not all signals are used for the soundboard. Are there other boards in need of this connector
and if yes, which signals I need to 'emulate'?

3)
Data East differences: I found differences in the power connector and in numbering of the special solenoids
and plan to spend a seperate power connector for Data East and solve the special solenoid numbering with software
Are there any other differences I need to take care off?

thanks for your help

Yes, thanks. I was aware of that.
Just wondering if there is more