Multiple Colormaps 8 Bits Per Pixel, Visual Types

HP OpenVMS I64 – Graphics Software Installation & Customization

ATI RADEON 7500 PCI Graphics Controller Installation Guide

Multiple Colormaps (8 Bits Per Pixel)

Multiple colormaps are not supported by the hardware. The ATI RADEON 7500 PCI graphics controllers support only one installed colormap at one time. Exceeding this limit in 8 bits per pixel depth, may cause colormap ‘flashing’, also known as "Technicolor".

Applications should not install or de-install colormaps themselves. The window manager should perform these actions. However, the application is responsible for providing the window manager with hints as to which colormaps to install or de-install.

Single Pixel Depth (No Mixed Depth Windows)

Some workstation 3D graphics options in the past provided the ability to mix windows of different pixel depths on the same screen. The ATI RADEON 7500 board can only support a single pixel depth at a time. This means that all windows on a specific screen must all have the same pixel depth (no mixed depth windows).

Visual Types

A visual type defines how the X11 server interprets the contents of a pixel. While the ATI RADEON 7500 hardware only supports a single pixel format at a time, the X11 server can emulate various visual types depending on the pixel depth. For example, when using 24 bits per pixel both DirectColor and TrueColor can be used, and at 8 bits per pixel all visual types are available.

The default visual types are: TrueColor for 16 and 24 bits per pixel, and PseudoColor for 8 bits per pixel.

For information on changing the default visual, see “Overriding the Default Settings” on page 11.

PCI Bus Performance Under Load

Under heavy load - typically mixed high output 2D and 3D - the RADEON 7500 may consume too much bus bandwidth, and has been observed to sometimes hang the graphics output. The DMA fetch size can be adjusted to use less bandwidth, at the cost of performance (typically 3D performance).

To reduce the DMA fetch size, modify DECW$PRIVATE_SERVER_SETUP.COM to include the line:

$ DEFINE/SYSTEM DECW$RADEON_FAST_DMA 0

This can be set to the values 0-2, where 0 is the lowest DMA fetch size. The default on Itanium systems is fast (2).

Open3D Support

The ATI RADEON 7500 supports hardware accelerated 3D support when the pixel depth is set to 24 bits per pixel. Hardware 3D drawing is not available when using 8 or 16 bits per pixel.

Previous versions of OpenVMS provided hardware accelerated 3D graphics and an OpenGL compatible programming interface for selected option cards through the Open3D license. Starting with OpenVMS V8.2 on both Alpha and I64 systems, the Open3D license will no longer be required for 3D operation (for POWERSTORM 300 and 350, and ATI RADEON 7000 and 7500 graphics controllers). The license for use of 3D is included as part of the base Operating System.

The OpenVMS ATI RADEON 7500 graphics support includes a Mesa3D based graphics library providing an OpenGL V1.2 compatible programming interface, and GLX V1.2. Among other features,

Chapter 3