Controller integrated circuit device for controlling a control unit by providing control data thereto

In a system including a display controller integrated circuit device for controlling an operation of a control unit which controls a CRT display, said control unit being coupled to said display controller integrated circuit device via a first external bus, external control means coupled to said control unit via said first external bus for controlling an operation of said control unit other than said operation controlled by said controller integrated circuit device, and a microprocessor coupled to said display controller integrated circuit device via a second external bus being different from said first external bus, said display controller integrated circuit device comprising:

• control data holding means for holding control data;
• synchronizing signal generating means for generating a horizontal synchronizing signal;
• first external terminals coupled to said first external bus;
• output means, coupled between said first external terminals and said control data holding means, for providing said control data to said first external bus during a period of time in which said horizontal synchronizing signal has a predetermined state;
• a second external terminal, coupled to said external control means, for providing a timing signal to said external control means;
• and
• timing signal generating means, coupled to said second external terminal and responsive to a state change in said horizontal synchronizing signal, for generating said timing signal;
• wherein said external control means fetches said control data in response to said timing signal to control said other operation of said control unit.