Hi Neil,

I know the S4 is ancient, actually almost 35y since release, but it goes well with what I want to use it for :)

I was hoping that you had higher resolution of the pictures you posted. It wouldn't be perfect of course since many things are obscured but it would be a start. But as it stands ...

Hi Neil,

Any chance for higher resolution pictures or some theory of operation or schematics ?
Looks like one 74hc595 and 2x 74hc166 and some passives.

I'm in the process of restoring two S4s and programming GAL/PAL for retro computing hobby is also something I was hoping to use them for.

Cheers ...