Analog Video

There had been different types of analog video and each differs on resolution and the maximum number of colors in its palette. Their evolution and types are discussed.

Monochrome – It is first video technology and was black-and-white video but, was sufficient for DOS operating system as DOS didn’t have any need for color. Images used only shades of grey called grayscale.

EGA and CGA – It was developed by IBM and was the first display device with color. Color Graphics Adapter (CGA) could display text, but it displayed graphics with a resolution of only 320 × 200 pixels with four colors and with resolution (640 × 200) using two colors—black and one other color. Enhanced Graphics Adapter (EGA) could display 16 colors out of a palette of 64 with a resolution of 320 × 200 or 640 × 350 pixels. Both were standard for color for long time.

VGA – Video Graphics Array (VGA) video technology had a 256KB of video memory on board and could display 16 colors at 640 × 480 pixels or 256 colors at 320 × 200 pixels. It became very popular. It’s an analog technology.

SuperVGA – The Video Electronics Standards Association (VESA) came out with a enhanced technology as a  public standard called SuperVGA (SVGA) which could support 16 colors at a resolution of 800 × 600 (the VESA standard), but it expanded to support 1,024 × 768 pixels with 256 colors.

XGA – Extended Graphics Array (XGA) was introduced by IBM.  It could support 256 colors at 1,024 × 768 pixels or 65,536 colors at 800 × 600 pixels. It was optimized for GUIs like Windows.

Other Analog Video – Other technologies are extensions of SVGA or XGA so, if it starts with letter W, it will have wider horizontal resolution to accommodate 16:9 or 16:10 wide-screen formats and if preceded with Q means horizontal and vertical resolutions were each doubled. So, if XGA with resolution of 1024 × 768, then QXGA resolution is 2048 × 1536and if SuperXGA (SXGA) has resolution of 1280 × 1024 then WSXGA have 1440 × 900.

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