Sigma Electronics Systems Display Generator 5564

[tony duell]

> Sounds really weird, six times memory and ALUs..? Maybe that another set of three CPU+MEMs are just for 
> another independend graphic layer?

Maybe, but I suspect it's more interesting than that.

> I noticed before, but there is VIDEO IN connector. What if this is video mixer, I mean system which you can 
> made text and etc. effects to over real time video... Where that video in goes,  to same video processor board..?

Yes, the 5 BNCs are wired to that 20 way ribbon cable (seen in the picture of the front view of the cardcage). That
plugs into the header on the video processor board. There are 2 wires each for the centre and shield of each BNC,
maybe to get the characteristic impedence of the cable correct.

My guess is that it is like the video input on the VT100. The video outputs from the unit are added (analogue)
to this signal and fed to the output BNCs. The external video source has to be synced to the terminal rather than
vice versa.

-tony