In this wiki page:http://en.wikipedia.org/wiki/Framebuffer
There is something called "SMART" protection capability to avoid monitor to driven it's hardware capabilities.
An unfortunate side-effect of this method was that the display device could be driven beyond its capabilities. In some cases this resulted in hardware damage to the display.[6] More commonly, it simply produced garbled and unusable output. Modern CRT monitors fix this problem through the introduction of "smart" protection circuitry. When the display mode is changed, the monitor attempts to obtain a signal lock on the new refresh frequency. If the monitor is unable to obtain a signal lock, or if the signal is outside the range of its design limitations, the monitor will ignore the framebuffer signal and possibly present the user with an error message.
How this works? Can anybody give me the mechanism behind this. I need to study a schematic which does implement this "SMART" protection capability. I have searched for the specification on google, but I didn't found it. How could I one implement this feature on a industrial CRT?