The VGA interface is a D-type interface with a total of 15 pinholes, divided into three rows, five in each row. Among them, in addition to 2 NC (Not Connect) signals, 3 display data buses and 5 GND signals, it is more important to have 3 RGB color component signals.
Number and 2 scan sync signals HSYNC and VSYNC pins. The color component of the VGA interface adopts the RS343 level standard. The peak voltage of the RS343 level standard is 1V. The VGA interface is the most widely used interface type on graphics cards, and most graphics cards have this type of interface. Some graphics cards with DVI (Digital Visual Interface) interface without VGA interface can also convert DVI interface into VGA interface through a simple adapter. Usually, the video card without VGA interface will be equipped with such adapter. .
Most computers and external display devices are connected through an analog VGA interface. The digital display image information generated inside the computer is converted into R, G, B primary color signals and lines and fields by the digital/analog converter in the graphics card. The synchronization signal is transmitted to the display device via a cable. For analog display devices, such as analog CRT displays, the signal is sent directly to the corresponding processing circuit, which drives the control tube to generate an image. For digital display devices such as LCD and DLP, a corresponding A/D (analog/digital) converter is required in the display device to convert the analog signal into a digital signal. After two conversions by D/A and A/D, some image details are inevitably lost. The VGA interface is useless for CRT displays, but it is used to connect display devices such as liquid crystals, and the image loss during the conversion process will slightly reduce the display effect.
Moreover, it can be judged from the interface whether the graphics card is a single display or an integrated graphics card. The vertical description of the VGA interface is an integrated graphics card, and the VGA interface is described as a separate graphics card (a general desktop host can use this method to view)