Meaning of SYSTEM.INI File's SVGAMODE= Setting

• Microsoft Windows operating system versions 3.1, 3.11

SUMMARY

This article discusses the Microsoft Windows operating system version 3.1 SYSTEM.INI SVGAMODE= setting.

The SVGAMODE= setting in the SYSTEM.INI file's [display] section is used by the Windows 3.1 Super VGA driver to remember the mode number needed to put the Super VGA adapter card into 800 x 600 16-color mode.

Note: The Windows 3.1 Super VGA (800 x 600, 16 colors) driver is not guaranteed to work with all Super VGA video boards.

MORE INFORMATION

When Windows is started with the SVGA display driver, it examines the SYSTEM.INI file's [display] section and looks for an SVGAMODE=<value> entry. If it finds it, the driver switches the card into the specified mode and then performs a hardware validity check to make sure the screen is in 800 x 600 16-color mode.

If the validity check fails, the SVGA driver runs through a list of common mode numbers, applying each one to the hardware, until one of the mode numbers successfully puts the adapter into 800 x 600 16-color mode. Once a successful mode number is found, the driver sets the SVGAMODE= setting in the SYSTEM.INI file.

Note: This value is in decimal (not hexadecimal). For example, if mode 29H is the 800 x 600 mode number for a given video adapter, then SVGAMODE=41 would be stored in the SYSTEM.INI file.

If the SVGA driver does not find SVGAMODE= in the SYSTEM.INI, then it performs the mode detection described above.

Higher Refresh Rates for VESA Boards

Generally, there is no reason to directly modify the SVGAMODE switch. When the SVGA driver is started, it will (in most cases) correctly identify the 800 x 600 mode number for the installed video board and use this number thereafter.

Some video boards, however, may have more than one 800 x 600 16-color mode -- for example, VESA-compatible video boards. VESA is an emerging standard for Super VGA video hardware. The standard mode number for 800 x 600 16-color mode for VESA-compatible video boards is 6AH (106 decimal). The mode-detection algorithm in the video driver, however, tests for this mode last. Because of this, Windows will not necessarily use mode 6AH for some VESA-compatible hardware. If a VESA video board is installed, it may be beneficial to edit the SYSTEM.INI file's [display] section and change SVGAMODE= to SVGAMODE=106.

This change will force the driver to initially use mode 6AH. With some VESA video boards, mode 6AH selects a faster (noninterlaced) screen refresh rate that is much more pleasing to the eye.