Display controller architecture for portable computers

1. A portable computer comprising:

a flat-panel display;

a display controller for outputting an internal video signal to the flat panel display;

means for receiving an external video signal;

a multiplexer for outputting either the internal video signal or the external video signal to the flat-panel display; and

an analog-to-digital converter and converter logic coupled between the receiving means and the multiplexer for converting the external video signal into a format required by the flat-panel display.

2. The portable computer of claim 1 wherein the receiving means includes a sensor for automatically sensing the external video signal and causing the multiplexer to output the external video signal for display.

3. The portable computer of claim 2 wherein receiving means includes a software driver that enables a user to manually select between displaying the internal video signal or the external video signal.

4. The portable computer of claim 3 wherein the receiving means includes a dual mode display connector coupled to the analog-to-digital converter for receiving the external video signal.

5. The portable computer of claim 3 wherein the portable computer includes an external CRT connector and wherein the receiving means includes a dual mode display adapter coupled to the external CRT connector for accepting the external video signal.

6. The portable computer of claim 5 wherein the portable computer further includes a second multiplexer coupled between the external CRT connector and a digital-analog-converter for isolating the output of the digital-analog-converter so that the external video signal may be received through the dual mode display adapter and the external CRT connector.

7. A method for enabling a portable computer to display an external video signal, the portable computer having a flat-panel display, the method comprising the steps of:

(a) providing the portable computer with means for receiving the external video signal;

(b) inputting an internal video signal to a multiplexer;

(c) inputting the external video signal to the multiplexer;

(d) providing the portable computers with dual display modes, such that in a first display mode, the multiplexer outputs the internal video signal to the flat-panel display, while in a second display mode, the multiplexer outputs the external video signal to the flat-panel display, thereby enabling the portable computer to act as a display device for an external computer; and

(e) coupling an analog-to-digital converter and converter logic between the receiving means and the multiplexer for converting the external video signal into a format required by the flat-panel display.

8. The method of claim 7 wherein step (a) further includes the step of: providing the receiving means with a sensor for automatically sensing the external video signal and causing the multiplexer to output the external video signal for display.

9. The method of claim 8 wherein step (a) further includes the step of: providing the receiving means with a software driver enables a user to manually select between displaying the internal video signal or the external video signal.

10. The method of claim 9 wherein step (a) further includes the step of: coupling a dual mode display connector to the analog-to-digital converter for receiving the external video signal.

11. The method of claim 9 wherein the portable computer includes an external CRT connector and wherein step (a) further includes the step of: coupling a dual mode display adapter to the external CRT for accepting the external video signal.

12. The method of claim 11 wherein step (a) further includes the step of: coupling a second multiplexer between the external CRT connector and a digital-analog-converter for isolating the output of the digital-analog-converter so that the external video signal may be received through the dual mode display adapter and the external CRT connector.