droms@burdvax.UUCP (06/12/84)
I bought a Motorola TTL-compatible monitor from the Xerox Mfg. Outlet in Texas which was claimed to be compatible with the Xerox 820-I boards from the same source. Has anyone else tried using this combination of equipment? I'm having a problem with the video display beginning before the vertical retrace is complete; about 10 horizontal scans are "folded" down from the top of the screen and overlap the remaining horizontal scans. I know the board works correctly when connected to a composite video monitor through an appropriate composite video generator. It appears that the vertical retrace is slower than the video generator on the 820-I board expects. Should I blame the monitor, the 820-I board or an incompatibility between the two? If the two are incompatible, what can I do to fix them? One solution is to stretch out the vertical retrace time on the 820-I board; unfortunately, that timing is all done with counters and requires cutting traces to adjust the values loaded into the counters. - Ralph Droms