Other Methods for Changing the Screen Resolution

Normally, the default screen resolution is sufficient for most users. However, you may need to change the default resolution if:

• You change the X Windows depth from the default listed in the table, then you should configure the screen depth to match the X Windows depth.

• The monitor does not "sync up" at the default screen resolution, then you need to choose a different screen resolution.

Guidelines

The general guidelines to follow when changing the default screen resolutions are:

• To run the X Windows environment in 8/24 mode, set the screen resolution to 24 bit-depth.

• By default, screen resolutions 1280 x 1024 and lower will automatically be set to 24 bit. Higher resolutions will default to 8-bit mode.

• Use GFXconfig -i to test a resolution before configuring the screen to that resolution.

Methods

The procedures for changing the screen resolution described in this chapter include:

• EDID Auto-Detect feature

• Output device method

• Video-Mode method

• Video-Timing method

EDID Auto-detect Feature for PGX32

If you are using a monitor with DDC2B/EDID protocol, the default resolution will be determined using the Auto-Detect feature. With this protocol, the GFX card first checks the Standard Timing Identifiers (taking the first one supported), then tries to match the Established Timings. Failing the above method, the card will default to 1152 x 900 x 66.

The monitor must be turned on prior to booting the system in order for the PGX32 to communicate with it.

The methods described in this appendix will override any information obtained via EDID.

output-device Method

It is possible to specify the screen resolution of PGX32 card via the output-device environment variable by using the format screen:rAxBxC, where:A is the desired horizontal resolution, B is the desired vertical resolution, and C is the desired refresh rate.

The system will check these values against an internal list of resolutions (see Table 6-3), and use the corresponding entry as the screen resolution.

For example, to use VESA1024 x 768 at 75 as the screen resolution, type the following at the ok prompt:

ok setenv output-device screen:r1024x768x75
ok reset

The new screen resolution will take effect following the reset, and will hold the resolution information until the output-device variable is changed manually.

Video Mode Method

At the ok prompt in Boot PROM mode, the screen resolution can be easily set on the PGX32 cards by using one of the 34 preinstalled resolution modes. These resolution settings are identified by video modes 0-33 (Table 6-3).

Use video modes 0-25 to select a screen depth of 24 bits, or video modes 26-33 to select a screen depth of 8 bits.

See "Using nvedit to Modify NVRAM" for a description of nvedit commands.

For example, to set the screen resolution to 1024 x 768 at 60Hz, video-mode 8, type:

ok nvedit
  0: 8 value video-mode  1: <ctrl-c>
ok nvstore
ok setenv use-nvramrc? true
ok reset

The last three commands enable the NVRAM. Without these lines, the changes you make with nvedit will be ignored.

Video Timing Method

If all of the previously described methods fail for your configuration, it is possible to specify the exact timing numbers for a particular resolution. The last method for setting the screen resolution also uses nvedit. This method is more involved and requires knowledge of all timing parameters for the desired resolution. Therefore, this method is only meant for monitors whose resolutions are not available in the Video-Mode Method. See "Using nvedit to Modify NVRAM" for a description of nvedit commands.

You should use this method only if the previous methods have been unsuccessful.

For example, to set the screen resolution to 1280 x 1024 at 76 Hz:

ok nvedit
 0: : video-timing " 1280, 384, 32, 64, \
		1024, 43, 3, 8, 135000000, 0" ;
 1:	<ctrl-c>
ok nvstore
ok setenv use-nvramrc? true
ok reset

The syntax is very important. The spaces must be present exactly as they appear in the example.

The last three commands enable the NVRAM. Without these lines, the changes you make with nvedit will be ignored.

Following is a brief description of the ten parameters used in this method.

• horizontal resolution (in pixels)

• horizontal blanking total

• horizontal front porch

• horizontal sync width

• vertical resolution (in lines)

• vertical blanking total

• vertical front porch

• vertical sync width

• dotclock in Hz

• sync value (see Table 6-4). Add the values together to select more than one.

To obtain the timing parameters required to use this method, contact SunService at 1-800-USA-4SUN with your monitor requirements.