XFree86

A popular free X server for UBOs.

82845G (i810) on Linux

$ lspci | grep VGA
0000:00:02.0 VGA compatible controller: Intel Corp. 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 01)

For this card you want to make sure you're using the i810 driver.

$ grep "LoadModule: \"i810\"" /var/log/XFree86.0.log
(II) LoadModule: "i810"

Here is the Device section of /etc/X11/XF86Config-4 where the Driver is defined, as well as VideoRam:

Section "Device"
       # You don't really need DRI defined here, as it's on my default with this driver.
       Option     "DRI"                        # [<bool>]
       Identifier  "Card0"
       Driver      "i810"
       VendorName  "Intel Corp."
       BoardName   "82845G/GL [Brookdale-G] Chipset Integrated Graphics Device"
       BusID       "PCI:0:2:0"
       # Note you can modify the number below, just remember that space will be taken from your RAM:
       VideoRam     8196
EndSection

The issue I was having is I couldn't get passed 8 bit mode even though I had the Depth variable set in the Screen section of my config file. It turns out you also need to have the DefaultDepth variable set. From /etc/X11/XF86Config-4

Section "Screen"
       Identifier "Screen0"
       Device     "Card0"
       Monitor    "Monitor0"
       DefaultDepth  24
       SubSection "Display"
               # Adjust the modes as per your requirements and capabilities
               Modes   "1024x768" "800x600"
               # 32 is not a valid depth value below.
               # Most  hardware  that uses 32 bits per pixel only uses 24 of them
               # to hold the colour information,  which  means  that  the  colour
               # depth is 24, not 32.
               # It could also be noted there is not much gain from 16 to 24 considering the
               # extra resources required.
               Depth   24
        EndSubSection
EndSection

Manuals to read for further information: XF86Config-4(5x) I810(4x)