cph1776 Posted April 29, 2016 Share Posted April 29, 2016 Hello all. Anyone ever try to connect a video signal to the "External VDP Input" (Pin 35) to the 9918A VDP? I could imagine using the TI 99/4A as a video titling system, if this actually worked.... Quote Link to comment Share on other sites More sharing options...
Stuart Posted April 29, 2016 Share Posted April 29, 2016 It should work (but I think pin 35 is grounded in the TI and would need to be disconnected). But the external signal and the VDP need to be sync locked together - details are in the 9918 datasheet. It's NOT just a case of connecting another video signal to pin 35. Quote Link to comment Share on other sites More sharing options...
Tursi Posted April 29, 2016 Share Posted April 29, 2016 I tried back in the day, it's pretty tough to get it right. But yes, you need to cut the sync pin and add a circuit to feed external sync at a high voltage... even if you get all that right... there was an article in Radio Electronics long enough that suggested the TI default clock might be off by too much to sync nicely (but that I'm not sure). I was able to switch back and forth between internal and external video, I just had trouble with syncing. Quote Link to comment Share on other sites More sharing options...
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