Olivetti graphics adapters are found in most Olivetti computers (including the M24, M28, M240, M280, and M380) and in the AT&T 6300 series computers. These adapters function the same as their non-Olivetti equivalents; that is, the OCGA, OEGA, and OVGA adapters support CGA, EGA, and VGA modes, respectively. In addition, Olivetti adapters can enter the high resolution _ORESCOLOR mode.
In _ORESCOLOR mode, you can choose one of 16 foreground colors by passing a value in the range 0–15 to the _selectpalette function. The background color is always black.