This is the first entry in a new series on Audio Visual equipment that is commonly used on a trade show floor. The most important thing to get right is the type of connections and their compatibility. There are many different types of connections, so it’s good to know what they are and what they can and cannot do. So let’s go over the names of the connections or ports and then we will take each one in some detail. In this series we will discuss VGA, HDMI, DVI, and the newest kid on the block – the Display Port.
First, there is VGA, which stands for Video Graphic Array. VGA, the original PC connection, was developed by IBM back in 1987. It started with a display resolution of 640 x 480, which is a very low resolution by today’s standard. VGA was followed by super VGA which gives you a higher resolution like 1024 x 768. Modern VGA can go even higher, depending on your video card and monitor.
All VGA connections transmit an analog signal. So what is an analog signal? Without going into too much detail, an analog signal can be defined as a continuous electrical signal. The video card in a computer converts the computer’s digital information into an analog format then transmits it through a VGA cable to the monitor.
So why are there 15 pins in a VGA connection? The short answer is, with the separation of the signals, a computer monitor can support many more pixels than a regular TV set. Pixels are the individual dots on a monitor screen that create the picture. For example: if a monitor can support an 800 x 600 picture format, that means it can display up to 800 pixels across and 600 pixels vertically. The more pixels you have, the better the picture.
So what are all the 15 pins in a VGA connection? Let’s have some fun and name them all:
- Red Out
- Green out
- Blue out
- It is unused. It doesn’t do anything
- Red return ground
- Green return ground
- Blue return ground
- Another unused pin.
- Sync return ground.
- Monitor ID 0 in
- Monitor ID 1 in, or data from the display
- Horizontal Sync out
- Vertical Sync
- Monitor ID 3 in or the data clock
You may be wondering why they don’t make it a 13-pin connection, since two pins are unused. Actually, I have no idea. My guess is they wanted to leave some room for future technology. Some VGA cables actually remove one of the unused pins, making it a 14-pin connection. So why not two pins missing? My guess there is for superstitious reasons – you know, unlucky number 13.
In a regular television all of these pins would be combined into a single composite video signal. You know it as the gold/yellow video pin that goes with the red and white audio pins. The quality of the picture is not as good as a multi-pin connection.