QVME (Level E-19 Drivers onwards), SMSQ/E for Atari ST & TT (QVME cards only)
The Atari range of computers can be attached to a wide range of monitors, some of which are able to display higher resolutions than others. A 17” multi-sync monitor, for example, can display resolutions of up to 1024x1024 (depending on make).
The QVME card is unable to detect the various parameters related to monitors and therefore allows you to set your own parameters either from SuperBASIC or by configuring SMSQ/E.
This command is used for setting the margins between the currently displayed QL screen and the edges of the monitor. This difference is known as the overscan (pixels available on the monitor which are currently unused). xblank sets the number of horizontal pixels x2 from the edge of the monitor to the left hand side of the QL screen.
The standard value for a 512x256 screen is 128 pixels (a standard QL monitor linked to an Atari can display a screen 640x480) (640-512)/2=64 pixels from the left hand side of the monitor.
If xblank is omitted or 0, then the original value is left unaltered.
Yblank sets the number of lines x 0.5 from the top of the monitor to the top edge of the QL screen. The standard value is 56, which gives a top margin of (480-256)/2=112 pixels from the top of the screen. If yblank is omitted or 0, then the original value is left unaltered.
If you use DISP_SIZE to alter the size of the displayed QL screen, it will automatically adjust the parameters for the overscan.
If the y parameter is used to alter the number of blank lines, this will override any setting of the line scan rate with DISP_RATE.
DISP_SIZE allows you to pass these parameters at the same time as amending the size of the displayed QL screen. DISP_RATE sets the frame and line scan rates for the display - if this command is used to adjust the line scan rate, this will alter the totoal number of lines.
Both SMSQ/E and QVME include programs to allow you to try out the various settings for the various DISP_… commands.