A monitor control system capable of reprogramming the function of a LCD monitor. The monitor control system utilizes VGA signal lines for video signal transmission during normal mode of operation and the same VGA signal lines for transmitting erase/record commands and data when the erasable programmable ROM inside the monitor demands reprogramming. Using an isolator circuit in the monitor control system for isolating an erase/record pathway of an erasable programmable ROM from a normal video pathway, data within the erasable programmable ROM can be modified without opening up the monitor casing. Hence, the modification of monitor function is much more convenient.