What does the slider bar in troubleshooting tab do?

It may sound like an OT question, but in fact it is not quite.
Our OpenGL app crashes on some PCs running Windows 2000.
It does not crash when the slider bar in the troubleshooting tab is lowered one level from Full in the display properties.
I am wondering what it actually disables?
I have searched around but found nothing.

I dont know for sure what is being disabled, but one or 2 notches will disable the ogl acceleration (a trick to run in software). I dont know its effect on Direct3D.

If its brought down to minimum, I beleive that blitting operations, and many other GDI operations are not used.

It could be that other things such as hard disk drivers may be effected: going from UDMA to some PIO mode.

I bet that those insider’s books released by MS press have this information. If you find something, let me know.

V-man

If you get a crash on win2k, I suspect the video drivers are at fault.

Anyway:

Full
This is the default setting and allows for full hardware acceleration.
Most
This setting adds the following items: SWCursor=1 to the [Display] section of the System.ini file.

Setting SWCursor to 1 disables the hardware cursor.

NOTE : This setting is similar to using the /Y switch with some versions of the MS-DOS-level Microsoft Mouse driver.

The Most setting applies to Western Digital (WD) or S3-compatible drivers. If you have problems with the way the mouse pointer appears on the screen, try this setting.
Basic
This setting adds the following items:

SafeMode=1 to the [Windows] section of the Win.ini file.

Setting SafeMode to 1 allows for basic acceleration only (for example, pattern bit block transfer [bitblt] and screen-to-screen bitblt).

MMIO=0 to the [Display] section of the System.ini file.

Setting MMIO to 0 disables memory-mapped I/O for S3-compatible drivers.

SWCursor=1 to the [Display] section of the System.ini file.

Setting SWCursor to 1 disables the hardware cursor.

Try the Basic setting if your computer seems to stop responding (hang) randomly and you have an S3-compatible video driver.

None
This setting adds the following items:
SafeMode=2 to the [Windows] section of the Win.ini file.

Setting SafeMode to 2 disables all video card acceleration (for example, the GDI calls the device-independent bitmap [DIB] engine directly for screen drawing, rather than using the display driver).

MMIO=0 to the [Display] section of the System.ini file.

Setting MMIO to 0 disables memory-mapped I/O for S3-compatible drivers.

SWCursor=1 to the [Display] section of the System.ini file.

Setting SWCursor to 1 disables the hardware cursor.

Try the None setting if your computer seems to hang randomly, you have an S3-compatible video driver, and the Basic setting does not resolve the problem.

This is from http://support.microsoft.com/default.aspx?scid=kb;EN-US;q127139