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The core specification of Open Firmware defines a terminal emulation support package that does not include support for colors. The Macintosh Open Firmware implementation supports additional SGR parameters to allow client programs to display characters and logos in a 16-color model.
For this expanded terminal emulation support to work, Open Firmware device drivers for display devices must initialize the first 16 entries of their color table to values defined in Table 5-11, where values are defined in terms of the fraction of full saturation required for each of the primary red-green-blue (RGB) colors.