Whole document tree OK, now you've computed HFL/VFL numbers for
your chosen dot clock, found the refresh rate acceptable, and
checked that you have enough VRAM. Now for the real black magic
-- you need to know when and where to place synchronization
pulses. The sync pulses actually control the horizontal and
vertical scan frequencies of the monitor. The HSF and VSF you've
pulled off the spec sheet are nominal, approximate maximum sync
frequencies. The sync pulse in the signal from the adapter card
tells the monitor how fast to actually run. Recall the two
pictures above? Only part of the time required for raster-
scanning a frame is used for displaying viewable image (ie. your
resolution). By previous definition, it takes HFL ticks to trace
the a horizontal scan line. Let's call the visible tick count
(your horizontal screen resolution) HR. Then Obviously, HR < HFL
by definition. For concreteness, let's assume both start at the
same instant as shown below: Now, we would like to place a sync
pulse of length HSP