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| Ramdac "ramdac-type" | This optional entry specifies the type of RAMDAC used on the graphics board. This is only used by a few of the X servers, and in most cases, it is not required because the X servers will probe the hardware to determine the RAMDAC type where possible. |
| DacSpeed speed | This optional entry specifies the RAMDAC speed rating (which is usually printed on the RAMDAC chip). The speed is in MHz. This is only used by a few of the X servers and only needs to be specified when the speed rating of the RAMDAC is different from the default built in to the X server. |
| Clocks clock ... | Specifies the dotclocks that are on your graphics board. The clocks are in MHz and may be specified as a floating-point number. The value is stored internally to the nearest kHz. The ordering of the clocks is important. It must match the order in which they are selected on the graphics board. Multiple Clocks lines may be specified. For boards with programmable clock chips, the ClockChip entry should be used instead of this. A Clocks entry is not mandatory for boards with non-programmable clock chips but is highly recommended because it prevents the clock probing phase during server startup. This clock probing phase can cause problems for some monitors. |
| ClockChip "clockchip-type" | This optional entry is used to specify the clock chip type on graphics boards that have a programmable clock generator. Only a few X servers support programmable clock chips. For details, see the appropriate X server manual page. |
| ClockProg command [textclock] | This optional entry runs command to set the clock on the graphics board instead of using the internal code. The command string must consist of the full pathname (and no flags). When using this option, a Clocks entry is required to specify which clock values are to be made available to the server (up to 128 clocks may be specified). The optional textclock value is to tell the server that command must be run to restore the text-mode clock at server exit (or when VT switching). textclock must match one of the values in the Clocks entry. This parameter is required when the clock used for text mode is a programmable clock. |
| The command is run with the real user's ID with stdin and stdout set to the graphics console device. Two arguments are passed to the command. The first is the clock frequency in MHz as a floating-point number and the second is the index of the clock in the Clocks entry. The command should return an exit status of 0 when successful and something in the range 1_254 otherwise. | |
| The command is run when the initial graphics mode is set and when changing screen resolution with the hotkey sequences. If the program fails at initialization, the server exits. If it fails during a mode switch, the mode switch is aborted but the server keeps running. It is assumed that if the command fails, the clock has not been changed. | |
| Option optionstring | This optional entry allows the user to select certain options provided by the drivers. Multiple Option entries may be given. The supported values for optionstring are given in the appropriate X server manual pages. |
| VideoRam mem | This optional entry specifies the amount of video RAM that is installed on the graphics board. This is measured in kilobytes. In most cases, this is not required because the X server probes the graphics board to determine this quantity. |
| BIOSBase baseaddress | This optional entry specifies the base address of the video BIOS for the VGA board. This address is usually 0xC0000, which is the default the X servers use. Some systems, particularly those with on-board VGA hardware, have the BIOS located at an alternate address, usually 0xE0000. If your video BIOS is at an address other than 0xC0000, you must specify the base address in the XF86Config file. Note that some X servers don't access the BIOS at all and those that do only use the BIOS when searching for information during the hardware probe phase. |