SVGA cables are a standard of 15-pin cables used to connect a computer to its display. The SVGA standard is derived from the earlier VGA standard. SVGA cables carry an analogue signal. The SVGA name also refers to a display standard that is usually used with displays connected through an SVGA cable.
The SVGA Name
The name SVGA stands for Super Video Graphics Array. The SVGA standard was developed in 1989 based on the Video Graphics Array standard defined by IBM two years earlier, although SVGA was actually defined by the Video Electronics Standards Association for broader use across the computer and video industries. SVGA is sometimes referred to as Super VGA or Ultra VGA in reference to its similarity to the VGA standard.
As with most computer display standards, SVGA refers not only to the 15-pin cable itself but also the display mode in terms of its resolution, colour depth, and refresh rate. Here, SVGA is technically superior to the VGA standard despite using similar hardware.
The VGA standard is very popular among personal computing. Over time it has come to refer to a series of related standards with different specifications. VGA standards range anywhere from a 320x200 resolution to the more common 640x480 (307k). Color depth for VGA is usually set as 4 bits per pixel, but in some cases of lower resolutions it is 8 bpp.
The SVGA standard included no such variables. It is set at an 800x600 (480k) resolution. This allows for a 4:3 aspect ratio, like a traditional non-wide-screen television. SVGA colour depth is set at 4 bpp with support for 16 million colours, depending on the graphics capabilities and video memory of the computer.
Analogue vs. Digital
While SVGA cables carry an analogue signal, it is important to understand what this means in the realm of digital computing. The computer's graphics card uses digital calculations to determine the output voltages that will be relayed to the display by the SVGA cable. Most analogue displays, such as CRT monitors, feature only a VGA or SVGA input. Digital displays may include both a VGA analogue input as well as a newer digital input standard (most often DVI, or Digital Visual Interface).
Even though is it a digital interface (sometimes referred to as non-analogue), DVI cables and devices may still display in SVGA mode with the same resolution and colour depth. Since many personal computers feature only one type of video output, SVGA to DVI adaptors are common, both in the form of cables and solid adaptors.
VGA and SVGA connectors are a common sight on many computers and displays. The cable and port feature the familiar trapezoid with 15 pins or holes arranged in an offset grid. VGA and SVGA input and output connections use the same D-subminiature ports, known as DE-15 or HD-15. An SVGA cable is the same as a VGA cable; only the data being transmitted (and the resulting display image) is different.
The 15 pins of an SVGA cable each control a specific function of the display standard. Each of the primary colours (red, green, and blue) is represented by a pin, with a second pin providing the ground for that colour. One pin carries the monitor ID. Another is the ground for the connection in general. Other pins are reserved for synchronising the display, both vertically and horizontally.
SVGA to XGA
Many computer displays built in the late-1990s or early-2000s refer to their VGA capabilities as XGA or Super XGA. Other common terms for the same standard are Super Extended Graphics Array (SXGA) and Ultra Extended Graphics Array (UXGA). While these terms were once intended to represent the new generation of analogue display standards, the ongoing improvements to the SVGA standard were actually done without changing the name or the cable used.
Today all XGA terminology is unofficial but generally refers to later versions of the SVGA standard, some of which are actually far superior to the original SVGA standard. By the mid-2000s, VGA monitors were largely obsolete and SVGA (along with all its variants) had become the industry standard for analogue display connections.