VGA was the last IBM graphics standard to which the majority of PC clone manufacturers conformed, making it the lowest common denominator that virtually all post PC graphics hardware can be expected to implement. It was officially followed by IBM's Extended Graphics Array XGA standard, but was effectively superseded by numerous slightly different extensions to VGA made by clone manufacturers, collectively known as Super VGA.

Today, the VGA analog interface is used for high definition video, including resolutions of p and higher. While the transmission bandwidth of VGA is high enough to support even higher resolution playback, there can be picture quality degradation depending on cable quality and length.

How discernible this degradation is depends on the individual's eyesight and the display, though it is more noticeable when switching to and from digital inputs like HDMI or DVI.

Video Graphics Array - Wikipedia

The VGA supports both All Points Addressable graphics modes, and alphanumeric text modes. The other color modes defaulted to standard EGA or CGA compatible palettes including the ability for programs to redefine the color EGA palette from a master color tablebut could still be redefined if desired using VGA-specific programming.

As well as the standard modes, VGA can be configured to emulate many of the modes of its predecessors EGACGAand MDAincluding their reduced global color palettes with particular pre-set colors chosen from the VGA palette for text and 4- or color, line modes and coarser text font grids.

Compatibility is almost full at BIOS level, but even at register level, a very high value of compatibility is reached.

VGA is not directly compatible with the special IBM PCjr or HGC video modes, despite having sufficient resolution, color, refresh rate and memory capabilities; any emulation of these modes has to be performed in software instead.

The intended standard value for the horizontal frequency of VGA is exactly double the value used in the NTSC-M video system, as this made it much easier to offer optional TV-out solutions or external VGA-to-TV converter boxes at the time of VGA's development, a technique proposed by Zia Shlaimoun.

All other frequencies used by the VGA card are derived from this value by integer multiplication or division. Since the exactness of quartz oscillators is limited, real cards will have slightly higher or lower frequency.

All derived VGA timings i. However, only the standard modes, or modes that at least use exactly the same H-sync and near-exact V-sync timings as one of the standard modes, can be expected to work with the original lates and earlys VGA monitors. The use of other timings may in fact damage such monitors and thus was usually avoided by software publishers. The figures shown in this image may be slightly inaccurate and not match the above table exactly.

The same general layout applies, merely at a lower frequency, for the vertical timings. Total vertical sync and blanking time 1. This does not usually cause a problem as the porches are merely intended to act as blanked-video buffers offering a little overscan space between the active area and the sync pulse which triggers, in traditional CRT monitors, the phosphor beam deflection "flyback" to the upper or left hand side of the tube and thus can be safely overrun into by a certain amount when everything else is operating correctly.

The relationship between the front and back porches can also be altered within certain limits, which makes possible special features such as software-based image alignment with certain graphics cards centering the image within the monitor frame by adjusting the location of the active screen area between the horizontal and vertical porches, rather than relying wholly upon the adjustment range offered by the monitor's own controls which can sometimes be less than satisfactory.

This buffer zone is typically what is exploited to achieve higher active resolutions in the various custom screen modes, by deliberately reducing porch widths and using the freed-up scan time for active pixels instead. It remains an option in XP and later versions via the boot menu "low resolution video" option and per-application compatibility mode settings.

The actual timings vary slightly from the defined standard. An alternative method of connecting VGA devices that maintains very high signal quality is the BNC connectortypically used as a group of five connectors, one each for Red, Green, Blue, Horizontal Sync, and Vertical Sync. With BNC, the coaxial wires are fully shielded end-to-end and through the interconnect so that no crosstalk or external interference is possible.

However, BNC connectors are relatively large compared to the DE 15, and some attention is needed to make sure each cable goes to the correct socket. Each cell may choose from one of 16 available colors for its foreground and eight colors for the background; the eight background colors allowed are the ones without the high-intensity bit set. Each character may also be made to blink ; all that are set to blink will blink in unison.

All of these options are the same as those on the CGA adapter as introduced by IBM.

Like EGA, VGA supports having up to different simultaneous characters on screen, albeit in only 8 foreground colors, by rededicating one color bit as the highest bit of the character number. Users may define their own character set by loading a custom font onto the card. As character data is only eight bits wide bookkeeping jobs from home alberta VGA, just as on all of its predecessors, there is usually a blank south african institute of stockbrokers exams column between any two horizontally adjacent glyphs.

However, some characters are normally made nine bits wide by repeating their last column instead of inserting a blank column, especially those defining horizontally connected IBM box-drawing characters. This functionality is hard-wired to the character numbers C0 hex to DF hexwhere all horizontally connecting characters are found in code page and its most common derivatives.

VGA adapters usually support both monochrome and color modes, though the monochrome mode is almost never used, and support for the vga output using mini displayport to vga adapter (optional) set of MDA text mode attributes intense, underline is often missing. Black and white text on nearly all modern VGA adapters is drawn by using gray colored text on a black background in color mode.

VGA monochrome monitors intended primarily for text were sold, but most of them will work at least adequately with a VGA adapter in color mode. Occasionally, a faulty job in bombay stock exchange between a modern monitor and video card will cause the VGA part of the card to detect the monitor as monochrome; this will cause the BIOS and initial boot sequence to appear in greyscale.

Usually, once the video card's drivers are loaded for example, by continuing to boot into the operating systemthey will override this detection and the monitor will return to color.

The video memory of the VGA is mapped to the PC's memory via a window in the range between segments 0xA and 0xBFFFF in the PC's real mode address space A Typically, these starting segments are:.

Due to the use of different address mappings for different modes, it is possible to have a monochrome adapter i. MDA or Hercules and a color adapter such as the VGA, EGAor CGA installed in the same machine. At the beginning of the s, this was typically used to display Lotus spreadsheets in high-resolution text on a monochrome display and associated graphics on a low-resolution CGA display java joptionpane.showinputdialog default value. Many programmers also used such a setup with the monochrome card displaying debugging information while a program ran in graphics mode on the other card.

Several debuggers, like Borland's Turbo DebuggerD86 by Alan J. Cox and Microsoft's CodeView could work in a dual monitor setup. Either Turbo Debugger or CodeView could be used to debug Windows. There were also DOS device drivers such as ox. It is also possible to use the "MODE MONO" command at the DOS prompt to redirect the output to the monochrome display.

The VGA color system is backward compatible with the EGA and CGA adapters, and adds another level of indirection to support 8-bit-colors.

CGA was able to display 16 fixed colorsand EGA extended this by using 16 palette registerseach containing a color value from a color palette. The default EGA palette values were chosen to look like the CGA colors, but it's possible to remap each color. This works in graphics and text modes. The signals from the EGA palette entries will drive a set of six signal lines on the EGA output, with two lines corresponding to one color off, dark, normal and bright, for red, green and blue.

These color registers are by default set to match the 64 default EGA colors. The values from these registers drive a DACwhich in turn drives three signal lines, one for red, green and blue. Using analog signals allows a theoretically unlimited number of color values on a default VGA cable. Like EGA uses the CGA color value to address a palette entry, the VGA hardware will also use the palette entries not directly as signal levels but as indexes to the color registers.

Therefore, in the color-modes, the color value from the RAM will reference a palette register and that palette register will select a color register.

The corresponding VGA color register 0x14 is preset to 42,21,0, or aa, also and off cause brown. For color-modes, using the 6-bit palette registers allows to use a block of up to 64 color registers, usually In the color-modes, the palette registers are set to have no effect and the DAC is set to combine two 4-bit color values into the original 8-bit-value; thereby the 8-bit color number in the video RAM is exactly the color register index to be used. Since the colors The other entries are 16 gray levels from black to white and 9 groups of 24 color values.

The remaining 8 entries were black see picture.

DisplayPort - Wikipedia

There is a trade-off for extra complexity and performance loss in some types of graphics operations, but this is mitigated by other operations becoming faster in certain situations:. The highest resolution modes were only used in special, opt-in cases rather than as standard, especially where high line counts were involved.

These modes were also outright incompatible with some monitors, producing display problems such as picture detail disappearing into overscan especially in the horizontal dimensionvertical roll, poor horizontal sync or even a complete lack of picture depending on the exact mode attempted. Several companies produced VGA compatible graphic board models. From Wikipedia, the free encyclopedia. This article is about the computer display standard.

For the pin video connector, see VGA connector. For a full list of display resolutions, see graphic display resolutions. For other uses, see VGA disambiguation.

Chips and Technologies 82c ATI Graphics Solution Plus S3 A i p p. ATI Wonder series Paradise Systems PEGA 1a S3 Vision Tseng Labs ET Cirrus Logic CL-GDs. ATI Mach series Paradise Systems PEGA 2a S3 Trio Tseng Labs ET Cirrus Logic CL-GDs.

Extended Graphics Array XGA Super Video Graphics Array SVGA. VGA compatible text mode. List of monochrome and RGB palettes8-bit RGBList of bit computer hardware palettesand MCGA and VGA. Retrieved 7 November Graphics Programming Black Book.

Audio and video connectors. Banana plug Binding post D-subminiature Euroblock DIN Mini-DIN Jack plug RCA Speaker spring terminal Speakon XLR. BNC Component RGB Component YPbPr Composite video D-Terminal DB13W3 DFP DIN Mini-DIN DMS LFH DVI Mini-DVI Micro-DVI RCA S-Video VGA Mini-VGA.

List of video connectors.

Audio and video interfaces and connectors. PC System Design Guide Connectors: RCA jack coaxial TOSLINK optical BNC Interface: RCA jack XLR TOSLINK optical BNC. RCA jack yellow Interface: Mini-DIN 4 Pin Interface: Composite S-Videoand Component Connectors: VIVO using Mini-DIN 9 Pin. Retrieved from " https: Products introduced in Computer display standards High-definition television IBM personal computers.

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