Chapter 3 Running OpenWindows on the SPARCstation 10SX and SPARCstation 20

This chapter discusses the visuals that are present when running OpenWindows on the SPARCstation 10SX and SPARCstation 20.

CG14 Pixel Modes for Running the Window System

The cgfourteen frame buffer is configurable to scan out either 8-bit pixels or 32-bit pixels. This allows the cgfourteen to be used in high resolution modes. For example, you can configure a 4MByte cgfourteen connected to a multi-sync monitor to display 8-bit pixels at 1280x1024 resolution with the command:

When the system is rebooted the monitor displays at the new resolution. Since 4MBytes is insufficient memory to have 32 bits per pixel, invoking OpenWindows will automatically select 8-bit pixels only.

The same hardware, when configured to display at 1152x900 resolution with the command:

will allow OpenWindows to use 32 bits per pixel, after rebooting.

In both modes, the left-over VRAM not displayed on the screen is utilized by the window system for pixmap allocation.

It is possible to use the frame buffer in 8-bit pixel mode even when there is sufficient VRAM for 32-bit pixels. There is a significant performance improvement when the frame buffer is in 8-bit pixel mode. To force the pixel mode, put the verb pixelmode="8" in the OWconfig file used by the server. The OWconfig file is typically in /usr/openwin/server/etc.

A complete entry with this in the file would look like:

Visuals Supported By Openwindows 3.3

When the window system runs in 8-bit mode, it exports the same visuals that are exported by Openwindows 3.3 on other 8-bit frame buffers:

• 8-bit StaticGray

• 8-bit GrayScale

• 8-bit StaticColor

• 8-bit PseudoColor

• 8-bit TrueColor and

• 8-bit DirectColor.

Only one hardware color lookup table is available to be shared by all X11 colormaps.

In 32-bit mode, the server supports a 24-bit TrueColor visual, in addition to all of the visuals present in 8-bit mode.

When the server is started with the following option:

the default visual, in which the root window is created, is an 8-bit PseudoColor visual.

When the following option is used:

the default visual is a 24-bit TrueColor visual.

False Color Effects

The phenomenon of seeing the wrong colors in a window because another X11 colormap is installed in the hardware is called false color.

The best way to avoid false color is to use a TrueColor visual. Since all 32 bits are available for TrueColor visuals, the colors always show up correctly. The SX hardware renders 24-bit visuals with the same speed as it renders 8-bit visuals, so there is no performance penalty when using 24-bit visuals.

In 32-bit mode the StaticGray visual has its own dedicated hardware color lookup table (actually a linear ramp). Hence StaticGray windows in 32-bit mode will never cause other 8-bit windows to appear incorrectly.