I'm learning computer graphics, and I read this course lecture in order to understand how graphics I/O works under the hood. But the following explanation was not very clear to me:
The values in the framebuffer are converted from a digital (1s and 0s representation, the bits) to an analog signal that goes out to the monitor. A video card’s RAMDAC performs this operation, once per frame. This is done automatically (not controlled by your code), and the conversion can be done while writing to the framebuffer.
RAMDAC get notified about the framebuffer write? Is there an IOCTL required from OS? or there is a circuitry somewhere that maps the write to