Re: Apple II video problem?

[David Wilson <mcs6502@gmail.com>]

On Jul 31, 4:19 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> AFAIK, the video sync, blanking, window timing was never changed
> in the ][->][+ line, so *something* weird is going on...

According to Winston D. Gayler in "The Apple II Circuit Description"
there were changes to video sync timing between Rev 0/1/7/RFI boards
(see page 157). The Hsync pulse changed from 7.8us to 3.9us between
Rev 1 and 7 while the Vsync pulse changed from 1.02ms to 255us between
Rev 0 and 1 (it also gained serrations). These changes should probably
not be visible (if only the trailing edge has moved). See also
Appendix G of Jim Sather's "Understanding the Apple II" for more about
the changes between the various revisions.