Hello!

I need to read from and write into my grafic card registers. I have the datasheet of this chip but i did not realy figure out how to access all that.

Table 4-9: Function :4 pci header registers for video controller summary
------------------------------------------------------------
F4 Index - Width(Bits) - Name
------------------------------------------------------------
00h-01h - 16 - Vendor Id
...
10h-13h - 32 - Base Adress Register (F4BAR)
...

Table 4-10: F4BAR: Video Controller Configuration Register Summary
------------------------------------------------------------
F4BAR+Memory Offset - Width(Bits) - Name
------------------------------------------------------------
00h-03h - 32 - Video Configuration Register
...


"... f4bar must be accessed using dword operation... when writing in one of this 32bit registers, all four bytes must be written."

What are you wanting to do? Access the basic VGA (aka 6845) controller, or do program the accelerator on the chip?

For the basic VGA stuff, you can still use the legacy ports 3b4h, 3c4h and 3d4h. (3b4 = mono, 3c4 = generic, 3d4 = colour).

i need to change the screen refresh rate in svga.

Have you looked at the VESA specs? (www.vesa.org). I'm pretty sure VESA includes functions for this...

PS. To change the refresh, rate requires calculating all the sync rates for the RAMDAC. (You'll end up basically programming the graphics mode by hand). Does the documentation you have, include all this info?