Why is the graphics on UNIX either slow or restricted to 8-bit displays?
C Electric’s internal graphics model uses an 8-bit deep frame buffer and a 256-long color map. Five of the 8 bits are for “transparent” layers (i.e. the most important layers of the current technology). Of the remaining three bits, one is for highlighting, one for the grid, and one is an “escape” which allows the 5 transparent layers to select one of 32 “opaque” colors. When something on a transparent layer needs to be drawn or erased, it is only necessary to set the write-mask to that bit-plane and do the graphics directly, without regard to anything on other layers. This makes the 5 most important layers draw more rapidly. The same argument applies to highlighting and grid setting. The problem on UNIX is that if a program demands all 256 color cell entries, the display flashes when the cursor roams in and out of the window (because the system is constantly switching the color map entries). Also, there seems to be a requirement that such programs use PseudoColor on an 8bpp display, as
