http://www.vintage-computer.com/vcforum/showthread.php?44362-Full-Page-Display-signal-on-a-non-FPD-monitor&p=339699#post339699
Again, this is based on a hunch that because pin 6 and 7 on the jumper for the 9 pin connector are bridged together that the system was meant to work with a TTL monitor with the same pinout as IBM MDA, but not necessarily the same frequency. (As I said in the thread, the logic goes like this: Intensity+Video == bright white/green/whatever on MDA, if you were working with a system that didn't do grayscale you might just tie intensity and video together so instead of 2 bit grayscale you get one bit B/W from a single TTL output.)
(EDIT: And yes, IBM MDA is, strictly speaking, two bit grayscale not "monochrome".)
Again, this is based on a hunch that because pin 6 and 7 on the jumper for the 9 pin connector are bridged together that the system was meant to work with a TTL monitor with the same pinout as IBM MDA, but not necessarily the same frequency. (As I said in the thread, the logic goes like this: Intensity+Video == bright white/green/whatever on MDA, if you were working with a system that didn't do grayscale you might just tie intensity and video together so instead of 2 bit grayscale you get one bit B/W from a single TTL output.)
(EDIT: And yes, IBM MDA is, strictly speaking, two bit grayscale not "monochrome".)