sis widescreen low resolutions bios patch

by **aicragleon** » Fri Apr 17, 2009 5:12 am

I flashed my HP Salmon (Asus K8S-LA) bios with the SIS video bios patch for widescreen resolutions 1440x900 and 1680x1050. I am now able to get 1440x900 and 1680x1050 and it works great. I am only unsettled that there are no lower resolutions in 16:10 like 1408x880, 1344x840, 1280x800, 1216x760, 1152x720, 1088x680, 1024x640, 960x600, 896x560, 832x520, or 768x480. I do not care that the screen wont look so clear. I am almost legally blind and would like to use lower screen resolutions for different programs and keep the aspect ratio. I am tired of using 800x600 and 640x480. Is it possible to make a patch like that?

by **Denniss** » Sat Apr 18, 2009 1:29 pm

AFAIR these resolutions are not supported by the currently available SIS Video Bios thus not available withing Windows. They may be available under Linux as these use more intelligent drivers.

by **aicragleon** » Sun Apr 19, 2009 3:19 am

I have the option of 960x600 and 1280x800 in the display properties but the monitor says it is displaying 800x600 when I switch to 960x600 and it says it is displaying 1024x768 when I switch to 1280x800 so the screen is cutoff, not a virtual desktop, just cut. I pulled the 12th pin out of the vga cable so nothing from the computer could read the monitor's DDC info but that did not do anything other than give me the ability to use a higher that native screen resolution which is the exact opposite of what I was trying to do. I also used moninfo from entech and phoenix edid designer to see if a custom inf file could do anything but it did not work.

So since I have the option of 1280x800 and 960x600, isn't there a way to make them work properly?

by **aicragleon** » Mon Apr 27, 2009 1:04 am

You say these resolutions are not supported by the currently available SIS Video Bios thus not available within Windows, is that for my bios HP Salmon (Asus K8S-LA)? I have seen laptops online with sis 760 chipsets and 1280x800 native screen resolutions for the screen. Shouldn't that mean it is possible for me to have a proper 1280x800 resolution?

by cp » Mon Apr 27, 2009 6:52 pm

LCDs in laptops are connected via a special chip (SIS301) to the vga controller. it is setup via the video bios which contains special register tables for it. those tables must be integrated in the video bios by the laptop manufacturer.

for the 15pin VGA output there are tables in the SIS video bios, too. they are the timing tables for different resolutions (search for modeline if you want to know more about it). SIS added a few 16:9 resolutions to their video bios starting with 2.28.00 but the table is far from complete. to make it worse they are just using their video bios table rather than shipping new tables with their drivers.

on the other hand there are 3rd party linux drivers which come with their own modeline tables and allow almost any resolution as long as the PLL in the SIS vga chip can generate the required frequencies.

a real patch would mean to disassemble the whole video bios, check how the windows drivers access the tables and add new tables. all this would be hard reverse engineering work and i doubt that anyone would be desperate enough to do it (at least i'm not). you should rather use Linux with its excellent 3rd party drivers or buy a cheap non-SIS add-on vga card.