| 摘要 |
An optional display detecting apparatus is used in a computer system which has a flat panel display serving as a standard display unit and allows a CRT display serving as an optional display unit to be connected thereto. The apparatus includes a data replacing circuit for selecting a predetermined one of color registers in a digital-to-analog converter (DAC) and replacing color data stored in the selected color register with the test color data upon power-on of the computer system, and a voltage detector for comparing voltage levels at output terminals of the DAC with a reference level to determine whether the CRT display is connected thereto. A display controller drives a display unit selected according to comparison result from the voltage detector.
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