The VGA Test Box project allows a normal microcontroller to output directly to a CRT monitor for testing.

“The goal of this project is to create a device that is capable of outputting VGA signals to a CRT monitor in order to display figures, text and characters. Timing is a core essential in this project. If the signal is off by even 1 microsecond, the signal synchronization with the CRT display will be lost and forced to resync. This will be done using a Microchip PIC microcontroller at 4 MHz clock speed. The programming required to achieve the VGA timing signals must be done in low level assembly because of the high level of precision that is necessary. The hardware assembly is just basic buttons, switches & wire that you can purchase from local electronics stores.”