HCRX Family Device Descriptions

This section describes the HCRX family of devices, including the HP VISUALIZE devices. This information applies to HCRX devices with or without IVX hardware. The following devices are included in the HCRX family:

HCRX-8
HCRX-8Z
HP VISUALIZE-8
HCRX-24
HCRX-24Z
HP VISUALIZE-24

Note that only the HCRX-8 and HCRX-24 can support IVX hardware.

The graphics accelerators on these devices do not affect IVL performance or functionality. So, for the rest of this chapter, all references to HCRX-8 will apply to HCRX-8, HCRX-8Z, and HP VISUALIZE-8 devices, and all references to HCRX-24 apply to HCRX-24, HCRX-24Z, and HP VISUALIZE-24 devices.

These devices are all similar, and include hardware support for the following operations:

Writing pixels to the frame buffer.
Moving a block of pixels from one place in the frame buffer to another.
Overlay plane transparency.
Clipping.

Device Descriptions

HCRX-8 Description

The HCRX-8 device is a color display with two image-plane banks of 8 planes each. It supports 8 planes single-buffered or 8/8 planes double-buffered in the image planes. The image planes include two hardware color maps.

The HCRX-8 also has 8 overlay planes. It includes two hardware color maps in the overlay planes. The overlay color maps do not support transparency by default.

The default overlay visual has 256 entries per color map and no overlay transparency. When overlay transparency is enabled, the default overlay visual has 252 entries per color map. See the information below about color map limitations when using overlay transparency on the HCRX-8 devices.

See the Graphics Administration Guide for information on pixel resolution and refresh rates for these and other devices.

HCRX-24 Description

The HCRX-24 device is a color display with one image-plane bank of 24 planes. The image planes include two hardware color maps.

The HCRX-24 supports the following image-plane buffer modes:

8 planes single-buffered
8/8 double-buffered
12 planes single-buffered
12/12 double-buffered
24 planes single-buffered

The HCRX-24 also has 8 overlay planes. It includes two hardware color maps in the overlay planes. One of the overlay color maps supports transparency by default.

The default overlay visual has 256 entries per color map and no overlay transparency. The second overlay visual has 255 entries per color map and supports overlay transparency. See the information below about using overlay transparency on the HCRX-24 devices.

See the Graphics Administration Guide for information on pixel resolution and refresh rates for these and other devices.

Supported Visuals

HCRX-8

The following visuals are supported by IVL on the HCRX-8 in the overlay planes:

PseudoColor (depth 8)

The following visuals are supported by IVL on the HCRX-8 in the image planes:

PseudoColor (depth 8)

HCRX-24

The following visuals are supported by IVL on the HCRX-24 in the overlay planes:

PseudoColor (depth 8)

The following visuals are supported by IVL on the HCRX-24 in the image planes:

PseudoColor (depth 8)
DirectColor (depth 12 or 24)
TrueColor (depth 12 or 24)

Color Map Management

The information in this section applies to both the HCRX-8 and HCRX-24 devices.

Because so many applications use the default X11 color map, and because the HCRX devices have two hardware color maps in the overlay planes, the behavior on these devices is to dedicate (that is, lock) one overlay hardware color map to always hold the default X11 color map. This means that the assigned default overlay hardware color map cannot have another color map downloaded to it. The other overlay hardware color map is available to applications that use color maps other than the default.

Changing the Default Visual

By default, the default visual (where the root window and default color map reside) is in the overlay planes. Also by default, the overlay planes have the default X11 color map permanently locked into one hardware color map, and the second hardware color map is available for applications to use.

You can change this default mode by moving the default visual into the image planes. Doing this will limit the number of hardware color maps available to you. In this mode, HCRX devices provide a single hardware color map in the overlay planes.

To move the default visual into the image planes, edit your X*screens file, and add "depth 8 doublebuffer" to the line for your special device file. For example, if your X0screens file has the following line for its special device file:

   /dev/crt

then you should change the line to read:

   /dev/crt depth 8 doublebuffer

Overlay Transparency

Overlay Transparency with HCRX-8 Devices

Overlay transparency mode is not available on HCRX-8 devices by default. Enabling overlay transparency mode on an HCRX-8 will limit your system to one hardware color map in the overlay planes and one hardware color map in the image planes. This will increase the likelihood of seeing a "technicolor" effect.

To enable transparency, set the Screen Option EnableOverlayTransparency, then restart the X server.

With this mode enabled, color maps created in the default visual have 256 entries, with entry 255 reserved for transparency. Remember that if transparency is not enabled, only 252 entries are available in the color map.

Overlay Transparency with HCRX-24 Devices

Unlike the HCRX-8 devices, overlay transparency is available by default on the HCRX-24 devices, and using overlay transparency on the HCRX-24 devices does not change the number of available hardware color maps.

To create an overlay color map that supports transparency, create the color map using the visual that has transparency in its SERVER_OVERLAY_VISUALS property. The default overlay visual has a transparent type of 0 (None), and the transparent overlay visual has a transparent type of 1 (TransparentPixel). See the file /usr/lib/X11/Xserver/info/screens/hp for more information.

In overlay color maps that support transparency, the number of color map entries will change from 256 to 255 because the last entry becomes the transparent color map value. If your application requires that you have 256 entries in your color map, you need to set the HP_COUNT_TRANSPARENT_IN_OVERLAY_VISUAL environment variable to any value (for example, TRUE) before starting the X11 server. The X11 server will ignore any attempt to modify entry 255 of the color map.