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From: thad@cup.portal.com (Thad P Floryan)
Newsgroups: comp.sys.3b1,comp.sys.att
Subject: External 3B1 Monitor Project Status; and help needed
Message-ID: <38705@cup.portal.com>
Date: 31 Jan 91 13:46:46 GMT
Organization: The Portal System (TM)
Lines: 49

[ Apologies if there are multiple copies of this posted; not ONE have I seen
  here or on the other systems I've checked, so I can only assume postings are
  NOT exiting PORTAL even though I've (re-)posted this at least 20 times now.
  I will have some new accounts on other systems within the next 20 hours so
  THAT problem will be corrected.]

--------------------

Welllll, most aspects of the External Monitor Project are working well, esp.
after inverting the vertical sync signal.

Only real problem remaining seems to be due to the 3B1 not quite producing a
"Hercules" compatible video signal ... my guess is the onset of the video
information seems to be too soon after a horizontal sync, causing the first
several pixels on each line to not be displayed.

Attempts to delay the video by running through a l-o-n-g chain of inverters
doesn't do anything discernibly different and I'm wondering if a digital delay
line might be necessary.

If anyone has experience with "digital" video (contrasted with "analog" video)
or can point me to some reference books that might address this kind of
problem, I'd be greatly appreciative.

It also seems that "Hercules"-compatible monitors don't have any horizontal
width adjustments meaning the 3B1's display doesn't span the entire CRT.

Several different monitors I've checked also have only the same four internal
potentiometer adjustments the BTC monitor has (besides the "external" bright
and contrast controls):

	focus
	video intensity
	vertical linearity
	vertical height

Contrast that with the complete array of adjustments available with the stock
3B1 monitor.  Sigh.

And it appears the Hercules monitors automatically center the image on the CRT
face, so it would appear that some method of "stretching" the horizontal scan
is needed (to fill the CRT left-to-right).  Again, any ideas or pointers to
reference material would be appreciated.

[ Due to PORTAL problems, I'm "moving" to some new sites, so please don't
  email any replies to this until I post the new email address(es); a posting
  response would be appreciated. ]

Thad Floryan