The basic principle of VGA

Display Principle
The colors displayed on the screen of a VGA monitor are composed of the three basic colors: R (Red), G (Green), and B (Blue). The cathode ray tube (CRT) emits an electron beam, which strikes the fluorescent screen to generate the three primary colors. VGA image display is achieved through either line scanning or interlaced scanning by the CRT, where the input signal starts from the top left corner of the display screen and scans from left to right and from top to bottom in a row-by-row manner. The line scanning signal HS controls the scanning from left to right, while the field scanning signal VS controls the scanning from top to bottom. After the electron beam scans one row, it returns to the starting position of the next row. The CRT suppresses the electron beam with the line synchronization signal HS, and performs line synchronization. Once all the line scans are completed, the field synchronization signal VS performs field synchronization, and simultaneously performs field suppression, causing the electron beam to return to the top left corner of the screen.

Pin definition

There are at least four versions of the VGA interface, namely the original version and the three-row 15-pin DE-15 with DDC15 pins, the less functional and less common 9-pin VGA, and the Mini-VGA for laptops.