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Various computer display standards or display modes have been used in the history of the personal computer. They are often a combination of display resolution (specified as the width and height in pixels), color depth (measured in bits), and refresh rate (expressed in hertz). Associated with the screen resolution and refresh rate is a display adapter. Earlier display adapters were simple frame-buffers, but later display standards also specified a more extensive set of display functions and software controlled interface.
Until recently, most computer monitors had a 4:3 aspect ratio and some had 5:4. Recently, monitors with 16:9 and 16:10 aspect ratios have become available, leading to new widescreen formats. Productive uses for such monitors, i.e. besides widescreen movie viewing and computer game play, are the wordprocessor display of two standard letter pages side by side, as well as CAD displays of large-size drawings and CAD application menus at the same time. The VESA industry organization has defined several standards related to power management and device identification. Ergonomy standards are set by the TCO.
Standards
A number of common resolutions have been used with computers descended from the original IBM PC. Some of these are now supported by other families of personal computers. These are de-facto standards, usually originated by one manufacturer and reverse-engineered by others, though the VESA group has co-ordinated the efforts of several leading video display adapter manufacturers. Video standards associated with IBM-PC-descended personal computers include:
| Video standard | Description | Display resolution (pixels) | Aspect ratio | Color depth (2^bpp colors) |
|---|---|---|---|---|
| MDA | Monochrome Display Adapter, the original standard on IBM PCs and IBM PC XTs with 4 KB video RAM. Introduced in 1981 by IBM. Supports text mode only. | 720×350 (text) | 72:35 | 1 bpp |
| CGA | Color Graphics Adapter. Introduced in 1981 by IBM, as the first color display standard for the IBM PC. The standard CGA graphics cards were equipped with 16 KB video RAM. | 640×200 320×200 160×200 | 16:5 16:10 4:5 | 1 bpp 2 bpp 4 bpp |
| Hercules | A monochrome display capable of sharp text and graphics for its time of introduction. Very popular with the Lotus 1-2-3 spreadsheet, which was one of the PC's first killer apps. Introduced in 1982. | 720×348 | 60:29 | 1 bpp |
| EGA | Enhanced Graphics Adapter. Introduced in 1984 by IBM. A resolution of 640 × 350 pixels of 16 different colors (4 bits per pixel, or bpp), selectable from a 64-color palette (2 bits per each of red-green-blue). | 640×350 | 64:35 | 4 bpp |
| Professional Graphics Controller | With on-board 2D and 3D acceleration introduced in 1984 for the 8-bit PC-bus, intended for CAD applications, a triple-board display adapter with built-in processor, and displaying video with a 60 Hz frame rate. | 640×480 | 4:3 | 8 bpp |
| MCGA | Multicolor Graphics Adapter. Introduced on selected PS/2 models in 1987, with reduced cost compared to VGA. MCGA had a 320x200 256 color (from a 262,144 color palette) mode, and a 640x480 mode only in monochrome due to 64k video memory, compared to the 256k memory of VGA. | 320×200 640×480 | 16:10 4:3 | 8 bpp 1 bpp |
| 8514 | Precursor to XGA and released about the same time as VGA in 1987. 8514/A cards displayed interlaced video at 43.5 Hz. | 1024×768 | 4:3 | 8 bpp |
| VGA | Video Graphics Array, introduced in 1987 by IBM. VGA is actually a set of different resolutions, but is most commonly used today to refer to 640 × 480 pixel displays with 16 colors (4 bits per pixel) and a 4:3 aspect ratio. Other display modes are also defined as VGA, such as 320 × 200 at 256 colors (8 bits per pixel) and a text mode with 720 × 400 pixels. VGA displays and adapters are generally capable of Mode X graphics, an undocumented mode to allow increased non-standard resolutions. | 640×480 640×350 320×200 720×400 (text) | 4:3 64:35 16:10 9:5 | 4 bpp 4 bpp 4/8 bpp 4 bpp |
| SVGA | Super VGA, a video display standard created by VESA for IBM PC compatible personal computers. Introduced in 1989. | 800×600 | 4:3 | 4 bpp |
| XGA | Extended Graphics Array is an IBM display standard introduced in 1990. XGA-2 added 1024 × 768 support for high color and higher refresh rates, improved performance, and support for 1360 × 1024 in 16 colors (4 bits per pixel). | 1024×768 640×480 | 4:3 4:3 | 8 bpp 16 bpp |
| QVGA | Quarter VGA (320x240) | 320×240 | 4:3 | |
| SXGA | Super XGA, a widely used de facto 32 bit Truecolor standard, with an unusual aspect ratio of 5:4 instead of the more common 4:3 which means, if scaled, images appear wider on SXGA displays than most other resolutions. The resolution probably should have been 1280 × 960 which is a popular standard resolution for Unix workstations. | 1280×1024 | 5:4 | 32 bpp |
| Ultra XGA is a de facto Truecolor standard. | 1600×1200 | 4:3 | 32 bpp | |
| WUXGA | Widescreen Ultra Extended Graphics Array is a version of the UXGA format. This display aspect ratio is becoming popular in high end 15" and 17" widescreen notebook computers. | 1920×1200 | 16:10 | 32 bpp |
| WQXGA | Widescreen Quad Extended Graphics Array is a version of the XGA format. This display aspect ratio is becoming popular in some recent desktop monitors. | 2560×1600 | 16:10 | 32 bpp |
| WXGA | Widescreen Extended Graphics Array is a version of the XGA format. This display aspect ratio is becoming popular in some recent notebook computers. | 1280×720 or 1280x800 | 16:9 or 16:10 | 32 bpp |
| WSXGA, or WXGA+ | Widescreen Extended Graphics Array PLUS is a version of the WXGA format. This display aspect ratio is becoming popular in some recent notebook computers. | 1440×900 | 16:10 | 32 bpp |
There also exist higher standards, such as QXGA and HXGA, with the highest resolution and de facto standard resulting from this nomenclature being WHUXGA at 7680 × 4800 pixels.
Display resolution prefixes
Although the common standard prefixes super and ultra don't indicate specific modifiers to base standard resolutions, several others do:
- Quarter (Q)
- A quarter of the base resolution. E.g. QVGA, a term for a 320×240 resolution, half the width and height of VGA, hence the quarter total resolution. This prefix is usually for "Quad" in higher resolutions.
- Wide (W)
- The base resolution increased, and not lowered, for square or near-square pixels on a widescreen display, usually with an aspect ratio of either 16:9 or 16:10.
- Quad(ruple) (Q)
- Four times as many pixels compared to the base resolution, i.e. twice the horizontal and vertical resolution respectively.
- Hex(adecatuple) (H)
- Sixteen times as many pixels compared to the base resolution, i.e. four times the horizontal and vertical resolutions respectively.
- Ultra (U)
- eXtended (X)
These prefixes are also often combined, as in WQXGAor WHUXGA.
Other resolutions
There are also some other 4:3 ratio resolutions such as 1400x1050 SXGA+ and unnamed ones like 1152x864.
See also
External links
Display technology | Graphics standards | VESA
Grafikstandard | Risoluzioni standard | Standaard voor weergavemodus | 画面解像度 | Tietokoneen näyttöstandardi | 电脑显示标准
"Computer display standard"