Quantum Data 801GC, 801GF, 801GX manual Hspw = Htot x Hrat x Pulse Width

in units of pixels, use this value for HSPW. Here is another way to calculate the value for HSPW from other data on your spec sheet:

•A spec sheet may give you the horizontal sync pulse width in micro-seconds. The value for HSPW can be calculated with this formula:

HSPW = HTOT x HRAT x Pulse Width

Where Pulse Width is in units of seconds and HRAT is in units of Hz. Remember to round the result to the nearest integer.

We are now done with the horizontal timing and can move on to the vertical timing. The first vertical timing parameter, SCAN, determines if a given for- mat will have a non-interlaced or 2:1 interlaced vertical scanning mode. Here are a few ways to determine the correct mode if it is not clearly stated on your spec sheet.

•Non-interlaced scanning is sometimes called “Progressive Scan” on a spec sheet.

•References to “odd” and “even” fields on a spec sheet usually indicate 2:1 interlaced op- eration.

•A “Field Rate” that is twice the “Frame Rate” on a spec sheet indicates 2:1 interlaced opera- tion.

The VRES parameter sets the number of active scan lines in a complete frame of video. This parameter may be called “Vertical Resolution” or “Vertical Ac- tive Pixels” on your spec sheet.

•The spec sheet for an interlaced display may give you the number of active lines for a single field. You will need to double this number to get the correct value for VRES.

6-52 Chapter 6: Programming Model 801GC, 801GF & 801GX¥Rev. A