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Q82734: Meaning of SYSTEM.INI File’s SVGAMODE= Setting

Article: Q82734
Product(s): Microsoft Windows 95.x Retail Product
Version(s): WINDOWS:3.1,3.11
Operating System(s): 
Keyword(s): 
Last Modified: 02-OCT-1999

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The information in this article applies to:

- Microsoft Windows versions 3.1, 3.11 
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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.

Additional query words: 3.10 3.1

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Keywords          :  
Technology        : kbWin3xSearch kbZNotKeyword3 kbWin310 kbWin311
Version           : WINDOWS:3.1,3.11

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