VGA stands for Video Graphics Array. VGA standard was first developed by IBM. It uses analog signals, delivers 640×480 resolution screen with 16 colors at a time and a refresh rate of 60 Hz. It displays a maximum of 256 colours at a time from the 262, 144 colours collection. It consists of a 6-Bit Digital to Analog converter to convert analog red, green and blue (RGB) signals.
History:
VGA was introduced by IBM in 1987 for its PS/2 line of PCs. The original VGA chipset(graphics card), was the first to offer capability for displaying up to 16 colours at a screen resolution of 640 × 480 pixels. Even at a lower resolution of 320 × 200 pixels, VGA could display up to 256 colours because of which made it easier to render lowercase letters.
Other manufacturers soon produced graphics cards displaying thousands to millions of colors but they were all supersets of VGA, the extension of VGA i.e the basis of all these graphic cards are the same because VGA is supported by all PCs. Because of this, it was used during the initial mode of loading of OS. For example, Microsoft Corporation’s Windows OS loaded its iconic opening splash screen in VGA color.
Characteristics of VGA:
- Resolution: VGA delivers a resolution of 640×480 pixels with 16 colours at a time.
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Output Capability: VGA supports both All Points Addressable graphics modes and alphanumeric text modes.
- Colour: VGA displays a maximum of 256 colours at a time from the 262, 144 colour collection.
- Refresh Rate: VGA has a refresh rate of 60 Hz.
- Memory: VGA has a memory utilization of 256k and it doesn’t have any supplementary memory.
Advantages:
- It is supported by all Personal Computers by any manufacturer.
- VGA has only one standard and no versions. If the equipment has a VGA-out, it will properly connect to a VGA-in.
- VGA signals are analog signals which means there will be more accuracy than digital signals
- VGA made it easier to render small letter characters and increased the clarity
- VGA was an improvement over the earlier predecessors like Enhanced graphic adapter which produced a maximum resolution of 320×200 pixels
- VGA signals can be easily split with simple distribution amplifiers . This makes VGA so simple.
- VGA cables can be used as a “universal” analog cable capable of transmitting RGBHV, YPbPr, composite, and s-video signals.
Disadvantages:
- It is an older technology with a limited amount of supported resolution.
- The color capacity of VGA is less than its successors.
- VGA cables must be a higher gauge for longer runs.