Quantum Data 801GC, 801GF, 801GX manual Active Video Physical Size, Display Codes

The frame rate is equal to HRAT divided by VTOT. This should match the frame rate given on your spec sheet.

Active Video Physical Size

The USIZ, HSIZ and VSIZ parameters do not affect the sync timing or signal outputs of the 801G*. They do, however, greatly affect the test images that are drawn. For example, the size of the box in the “Bright- ness” test pattern should match the size of your light meter probe. The actual size of the probe is entered using the system parameter MSIZ. The firmware com- bines this information along with the format’s physi- cal size information to properly scale the size of the box. The firmware also uses the format’s size infor- mation to make sure the crosshatch lines in the SMPTE RP-133 pattern form square boxes and that the circle is round and not elliptical.

The USIZ parameter determines whether the unit of measure will be interpreted as inches (1) or in mm

(2).

The HSIZ parameter is the horizontal width of the active video area on a properly adjusted display.

The VSIZ parameter is the vertical height of the active video area on a properly adjusted display.

❖Changing the values of HSIZ and (or) VSIZ will not change the overall size of most test images on your display.

Display Codes

Many video controller cards for the Apple Macin- tosh II and VGA type cards for the IBM-PC are able to identify the type of display connected to them by checking one or more display code sense lines com- ing from the display. The information is then used to select one of several different operating modes to match the display. An improper display code may make the controller card or display appear to be

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