Quantum Data 801GC - Manual (Page 176)

6-50 Chapter 6: Programming Model 801GC, 801GF & 801GX¥Rev. A
Timing Parameters
HRAT, sets the horizontal scan, or line, rate of the
format. This is the rate at which horizontal video
lines are produced. The 801G* uses Hertz as the unit
of measure while most display spec sheets may give
the rate in kilo-Hertz. The rate can easily be entered
as a floating point number. For example, a 15.73426374
kHz horizontal rate could be entered as 15734.26374
or as 15.73426374E3. Here are some ways to calcu-
late the value for HRAT if it is not given on your
spec sheet:
• If a spec sheets gives you the total horizontal
period, in micro-seconds, instead of the hori-
zontal rate. HRAT can be calculated as follows:
HRAT = 1 / Horizontal Period
• If a spec sheets gives you a dot clock or pixel
rate and the total number of active and blanked
pixels per line. HRAT can be calculated as
follows:
HRAT = Pixel Rate / Total Pixels per Line
The HRES parameter sets the number of active pix-
els in a single scan line. This parameter may be called
“Horizontal Resolution” or “Horizontal Active Pix-
els” on your spec sheet.
The HTOT parameter sets the total number of pix-
els (active + blanked) in one horizontal scan line. It
must be an even number. If your spec sheet gives
you the horizontal period in units of pixels, use this
value for HTOT. Here are some ways to calculate
the value for HTOT from other data on your spec
sheet:
• A spec sheet may give you the number of
horizontal active and blanked pixels as two
separate numbers. Simply add the two num-
bers together to get HTOT.