Monitor refresh rate query

[Peter Corlett]

On Mon, Jun 20, 2016 at 07:12:35AM -0400, Noel Chiappa wrote:
[...]
> Although how a monitor is supposed to tell whether a signal is interlaced, or
> non-interlaced, is not clear - there's certainly no pin on the VGA connector
> which says so! :-)

It's encoded in the sync signal. The timings are tweaked such that the beam of
a dumb CRT will be pushed down a half-line on alternate fields.