4. Modelines

When constructing a modeline for use with the Sis driver you'll need to consider several points:

• H/W Acceleration. The H/W cursor, and fill operations currently allocate memory of the video ram for there own use. If this is not available these functions will automatically be disabled. Also, ext_eng_queue allocate 32k of Vram.
• Dot Clock. SiS documents the following video modes to work with 6326. The max dot clock allowable for your 6326 based board depends also on the memory installed on it. Option fast_vram can be needed for high dot clocks to work. Of course, the memory installed must allow 1 cycle R/W. The server tries to avoid problems with high dotclocks, limiting the maximum based on estimated memory bandwidth. Overriding the limits with dac_speed and modelines can damage the card if you exceed the card limits. Values between driver guess and chipset limits are acceptable, but can cause bad image quality, noise or no image displayed.
  • SiS recommended video modes for 6326:
  • 640x480 : 4, 8, 15, 16, 24 bpp at 85Hz Non-interlaced
  • 800x600 : 4, 8, 15, 16, 24 bpp at 85Hz Non-interlaced
  • 1024x768 : 4, 8, 15, 16, 24 bpp at 85Hz Non-interlaced
  • 1280x1024 : 4, 8, 15, 16, 24 bpp at 75Hz Non-interlaced
  • 1600x1200 : 4, 8 bpp at 65Hz Non-interlaced