Matrox mga.mon settings for 6091 Mode 3:

Most of this should not be needed any more since the latest drivers are supposed to include support for the 6091. I will verify that in a couple of weeks.
Christopher A. Hudson (cahudson gate.net) was kind enough to send this to me. Quote:

Thought I'd pass along some stuff I found out which makes the 6091 very easy to use with Win95 and NT in "mode 3".
The Matrox Millenium has very flexible Win95 and NT drivers. You can directly set up all timing parameters yourself, which are then stored in a parameter file - mga.mon. Here are mga.mon settings which work with the 6091 in "mode 3" from 800x600 to 1280x1024. For anyone to use them, they only need to be appended to the end of the file.
A 2MB Millenium can now be found for $199 or a bit less. The modes up thru 1152x864 can be run at 16bit color depth, while 1280x1024 is limited to 8bit (unless you get 4MB). I use 1152x864. At the 75Hz refresh rate, its rock steady. The Millenium also uses the Ti 3026 220MHz RAMDAC, so the image is really sharp. Worth getting a good cable if you don't already have one.
You can see that the mga.mon format is in "H pixels" and "V lines" - so you can convert any working modeline with just a few subtractions. Or alternately develop modelines from these.
Note that the 640x480 are NOT for the 6091 - I use them with a cheap VGA B&W monitor for text, CMOS changes, etc.

[User-Defined.Customized IBM 6091 Mode 3]
640X480  =     NI, *User-Defined_Customized_IBM_6091_Mode_3_,(640X480)
800X600  =     NI, *User-Defined_Customized_IBM_6091_Mode_3_,(800X600)
1024X768  =     NI, *User-Defined_Customized_IBM_6091_Mode_3_,(1024X768)
1152X864  =     NI, *User-Defined_Customized_IBM_6091_Mode_3_,(1152X864)
1280X1024  =     NI, *User-Defined_Customized_IBM_6091_Mode_3_,(1280X1024)

[*User-Defined_Customized_IBM_6091_Mode_3_,(640X480)] ; GENERIC VGA @ 60Hz
PIXEL_CLK   =   25175
H_DISP   =   640
H_FPORCH   =   16
H_SYNC   =   96
H_BPORCH   =   48
H_SYNC_POL   =   0
V_DISP   =   480
V_FPORCH   =   10
V_SYNC   =   2
V_BPORCH   =   33
V_SYNC_POL   =   0
INTERLACE_ENABLE  =   0

[*User-Defined_Customized_IBM_6091_Mode_3_,(800X600)] ; Vf=85Hz Hf=66KHz
PIXEL_CLK   =   74377
H_DISP   =   800
H_FPORCH   =   64
H_SYNC   =   96
H_BPORCH   =   160
H_SYNC_POL   =   0
V_DISP   =   600
V_FPORCH   =   88
V_SYNC   =   3
V_BPORCH   =   88
V_SYNC_POL   =   0
INTERLACE_ENABLE  =   0

[*User-Defined_Customized_IBM_6091_Mode_3_,(1024X768)] ; Vf=83Hz Hf=68KHz
PIXEL_CLK   =   94252
H_DISP   =   1024
H_FPORCH   =   32
H_SYNC   =   192
H_BPORCH   =   128
H_SYNC_POL   =   0
V_DISP   =   768
V_FPORCH   =   11
V_SYNC   =   15
V_BPORCH   =   33
V_SYNC_POL   =   0
INTERLACE_ENABLE  =   0

[*User-Defined_Customized_IBM_6091_Mode_3_,(1152X864)] ; Vf=75Hz Hf=70KHz
PIXEL_CLK   =   112064
H_DISP   =   1152
H_FPORCH   =   72
H_SYNC   =   96
H_BPORCH   =   288
H_SYNC_POL   =   0
V_DISP   =   864
V_FPORCH   =   2
V_SYNC   =   15
V_BPORCH   =   36
V_SYNC_POL   =   0
INTERLACE_ENABLE  =   0

[*User-Defined_Customized_IBM_6091_Mode_3_,(1280X1024)] ; Vf=67Hz Hf=68KHz
PIXEL_CLK   =   119999
H_DISP   =   1280
H_FPORCH   =   16
H_SYNC   =   160
H_BPORCH   =   240
H_SYNC_POL   =   0
V_DISP   =   1024
V_FPORCH   =   3
V_SYNC   =   3
V_BPORCH   =   26
V_SYNC_POL   =   0
INTERLACE_ENABLE  =   0

END Matrox mga.mon settings