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VGA connector

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The Video Graphics Array, or VGA, is a standard connector used for computer video output.

VGA Port
VGA Port

It allows a computer to send visual information to a display device. This technology was vital for the growth of personal computing. It originated with the 1987 IBM PS/2 and its specific graphics system. Since then, the 15-pin connector became ubiquitous on PCs, monitors, and projectors. It even appeared on many high-definition television sets. While newer digital interfaces have largely displaced it, VGA remains an important part of computing history.

The most common VGA connector is a 15-pin D-subminiature design.

DE-9 and DE-15 video port comparison
DE-9 and DE-15 video port comparison

In technical terms, this is called a DE-15 connector. It features 15 pins arranged in three rows. The name refers to its "E" size shell. Some people also call it HD-15 or DB-15. The original IBM design used a unique feature on pin 9. This pin acted as a "key" to ensure correct connection. On the female connector, this pin was blocked. On the male connector, the pin did not exist at all. This meant some modern cables might not fit original IBM hardware without modification.

Electrically, a VGA connector carries analog RGBHV signals. These signals represent red, green, and blue colors. The "HV" stands for horizontal and vertical sync. These sync signals tell the monitor how to keep the image steady. The connector can also support other methods like RGsB or RGBS. Modern versions include VESA DDC pins. These pins allow the computer to identify the attached display device. This identification process is part of the Extended Display Identification Data, or EDID. This system helps the computer understand the capabilities of the monitor.

Before the 15-pin standard became the norm, other connectors were used. The DE-9 connector was used in the 1985 IBM Professional Graphics Controller. The DE-9 had only nine pins. It was used for older systems like the CGA and EGA. Some early VGA hardware makers used this 9-pin standard instead of the 15-pin version. Eventually, all manufacturers switched to the DE-15 standard. This move made the 9-pin version much less common.

DE-9 and DE-15 video port comparison
DE-9 and DE-15 video port comparison

This transition helped create a single, unified standard for all users.

Different industries have used different types of video connections. For example, some professional monitors and video cards use BNC connectors.

BNC connectors
BNC connectors

BNC connectors are large and circular. They provide a high-quality connection by using five separate 75 ohm coaxial cables. This prevents "crosstalk," which is when signals mix together. In a standard 15-pin VGA connector, the red, green, and blue signals are not shielded from each other. This shielding gap makes crosstalk possible in the 15-pin design. However, BNC connectors are bulky and require extra space to turn and disconnect.

Users can also find smaller versions of this technology. In the early to mid-2000s, some portable laptops used a mini-VGA connector.

Mini-VGA cropped
Mini-VGA cropped

This version is much smaller than the standard DE-15. You can also use adapters to connect different types of hardware. For instance, a DVI to VGA adapter works because many DVI interfaces carry analog signals. However, you cannot connect HDMI or DisplayPort to VGA without an active converter. This is because HDMI and DisplayPort are digital, while VGA is analog.

Asus VGA - Mini-VGA adapter-6605
Asus VGA - Mini-VGA adapter-6605

An active converter is required to change the signal type.

To maintain signal quality over long distances, people use VGA extenders. These are electronic devices that act like boosters. They increase the signal strength from a VGA port. This is helpful in schools or businesses where cables must be very long. Without a booster, the picture might appear blurry or show minor artifacts. The quality of the cable itself also matters for the image. Higher-quality cables often use coaxial wiring and thicker insulation. A correctly matched 75 ohm cable helps prevent "ghosting," which occurs when signals are reflected due to impedance mismatches.

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🖼️ Images & Media (6)
File:PC Monitor.svg
PC Monitor.svg
File:VGA Port.svg
VGA Port.svg
File:Mini-VGA cropped.jpg
Mini-VGA cropped.jpg
File:BNC connectors.jpg
BNC connectors.jpg
File:DE-9 and DE-15 video port comparison.jpg
DE-9 and DE-15 video port comparison.jpg
File:Asus VGA - Mini-VGA adapter-6605.jpg
Asus VGA - Mini-VGA adapter-6605.jpg
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