7 Jul
2007
7 Jul
'07
1:41 p.m.
A separate note in my diagrams says : 'VSync
75Hz,
HSync 16.1KHz'
How is this possible? This would mean 214.67 lines of
resolution (including overscan?). Am I goofy or something? I had thought the V/S output 400 lines of
resolution. Is it interlaced or sumthin? These
I think it has to be interlaced. That would then be about right for a
400-line interlaced image. The video timing is contorlled by a 6845,
which is quite capable of interlaced scanning, of course.
If it wasn;t interlaced, to get the same vertical resolution, either the
vertical frequency would haev to be halved (which I don't believe for an
instant -- did _any_ machine have a vertical sync frequency less than
50Hz?) or the horizontal would haev to be doubled. From waht I remember
of the hoprixontal output stage, I think that's unlikely too.
-tony