Shadow RAM control registers .

[nico]

Hi,

is there a way to find out which are the registers that control Shadow Ram write protect without having chipset datasheets.
I need them because i have to patch the bios code before OS is loaded but at that time shadow area F000:0000 to FFFF is already set to write protected status and i don't want to mod the bios on the flash.
The chipset on my board is Sis661FX but Sis doesn't supply tech documentation to end-users .

One way may be debug bios code and trace when it sets write protect but this way is system-depedant and changing the board will result in spending much time in debugging the new bios .

Could anyone help me ?
Thanks .
Nico

PS: Sorry for my bad english.