Configuring the Monitor Section

The Monitor section describes your monitor to X. You can define a number of monitors in the XF86Config file, as each Monitor section is named. The Screen section (discussed later) then connects a monitor to a video card. For example, the following abbreviated entry defines our NEC MultiSync XE17 monitor:

  Section "Monitor"

  Identifier  "NEC MultiSync XE17"

  VendorName  "NEC"

  ModelName   "MultiSync 4FGe"

  HorizSync   31.5 - 64.3

  VertRefresh 55-120

  # Modes from the NEC MultiSync 4FGe monitor, a close monitor.

  ModeLine "640x480"  31  640  680  704  832 480 489 492 520

  ModeLine "800x600"  50  800  864  976 1040 600 637 643 666

  ModeLine "1024x768" 81 1024 1068 1204 1324 768 776 782 807

  EndSection

For each monitor, you need to define the items listed in Table 3.13.

The identifier is a string used to refer to the monitor later. You can define more than one monitor in the XF86Config file.

The HorizSync range describes the horizontal sync frequencies for your monitor. It can be a set of comma-separated values or a range separated by a dash, such as 42-65, for multisync monitors. You should get this value from your monitor documentation (where you’ll find most of the key information needed here).

The format for a Modeline is:

     Modeline "name" horizontal-values vertical values

For example, the following sets up a standard VGA mode:

  # 640x400 @ 70 Hz, 31.5 kHz hsync

  Modeline "640x400"  25.175 640  664  760  800   400  409  411  450

There can be a whole set of modeline values. You can get this from the probeonly mode of X or from documentation that comes with XFree86. Some of the relevant documentation is listed in Table 3.14.

All these files are located in /usr/X11R6/lib/X11/doc. An example entry from the Monitors file follows:

  #Date: Sat, 17 Sep 1994 00:50:57 -0400

  #From: Erik Nygren <nygren@mit.edu>

  Section "Monitor"

     Identifier "NEC MultiSync 4FGe"

     VendorName "NEC"

     ModelName "MultiSync 4FGe"

     BandWidth 80Mhz        #\

     HorizSync 27-62KHz      #> from monitor documentation

     VertRefresh 55-90Hz    #/

     ModeLine "640x480"  31  640  680  704  832 480 489 492 520

     ModeLine "800x600"  50  800  864  976 1040 600 637 643 666

     ModeLine "1024x768" 81 1024 1068 1204 1324 768 776 782 807

  EndSection

One of the monitors we have, an NEC MultiSync XE17, was not in either the modeDB.txt or Monitors file. We found the closest monitor in the listing, an NEC MultiSync 4FGe, and experimented with those Modelines. Calculating the Modelines yourself is a real pain, so you want to find a monitor or a close facsimile in the Monitors or modeDB.txt files.

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WARNING:  Having said that, be careful about using Modelines for other monitors. You can destroy your monitor if you’re not careful.

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Configuring the Graphics Card Section

The Device section describes your graphics card to X. For example, a standard Super VGA device appears as the following:

  # Standard VGA Device:

  Device

     Identifier  "Generic VGA"    VendorName  "Unknown"

     BoardName   "Unknown"

     Chipset     "generic"

  #  VideoRam    256

  #  Clocks      25.2 28.3

  EndSection

A more detailed device section, for an Actix S3 accelerated card, follows:

  # Device configured by xf86config:

  Section     "Device"

  Identifier  "Actix GE32+ 2MB"

  VendorName  "Actix"

  BoardName   "GraphicsENGINE Ultra"

  #VideoRam   1024

  #Option     "dac_8_bit"

  Ramdac      "att20c490"

  Clocks      25 28 40 72 50 77 36 45 90 120 80 32 110 65 75 95

  EndSection

Of these options, the clocks are the hardest to fill in. One option is to try X in probeonly mode to fill in the details. You can also look in a file called AccelCards in /usr/X11R6/lib/X11/doc for more information on accelerated chipsets and cards. An entry from the AccelCards file follows:

  Card Vendor             : Actix

  Card Model              : GraphicsEngine32 Plus

  Card Bus (ISA/EISA/VLB) : ISA

  Chipset                 : S3 86C801

  Video Memory            : 2048k

  Memory Type (DRAM/VRAM) : DRAM

  Memory Speed            : 45ns

  Clock Chip              : Avasem AV9194-11

  Programmable? (Y/N)     : No

  Number of clocks        : 16

  Clocks                  : 25.175 28.322 40.0 0.0 50.0 77.0 36.0 44.9

  Clocks (cont)           : 130.0 120.0 80.0 31.5 110.0 65.0 75.0 95.0

  Option Flags            :

  RAMDAC                  : AT&T 20C490-11

  Submitter               : David E. Wexelblat <dwex@xfree86.org>

  Last Edit Date          : Sept 25, 1993

You can convert the Clocks lines into the proper syntax for the XF86Config file by placing the same values in order in a line (or lines) starting with Clocks in the Device section:

  Clocks 25.175 28.322 40.0 0.0 50.0 77.0 36.0 44.9

  Clocks 130.0 120.0 80.0 31.5 110.0 65.0 75.0 95.0

Be sure to put all the clock values in the original order.