Computer display standards are a combination of aspect ratio, display size, display resolution, color depth, and refresh rate. They are associated with specific expansion cards, video connectors, and monitors.
History
Various computer display standards or display modes have been used in the history of the personal computer. They are often a combination of aspect ratio (specified as width-to-height ratio), display resolution (specified as the width and height in pixels), color depth (measured in bits per pixel), 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.
Beyond display modes, the VESA industry organization has defined several standards related to power management and device identification, while ergonomics 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 are shown in the diagram and table below, alongside those of early Macintosh and other makes for comparison. (From the early 1990s onwards, most manufacturers moved over to PC display standards thanks to widely available and affordable hardware).
Table of computer display standards (by height and width)Video standardFull nameDescriptionDisplay resolution() Width() Height() AreaStorage aspect ratio (effectively: Display aspect ratio)Color depth (2^bpp colors)(pixels)(px)(px)(px)QQVGAQuarter Quarter Video Graphics ArrayUsed on some portable devices, and is a common alternative resolution to QCIF for webcams and other online video streams in low-bandwidth situations, and on video modes of early and later low-end digital cameras. (19k)160120 19,2004:3UNNAMEDUNNAMEDA common size for LCDs manufactured for small consumer electronics, basic mobile phones and feature phones, typically in a 1.7" to 1.9" diagonal size. This LCD is often used in portrait () orientation. The unusual 5:4 aspect ratio makes the display slightly different from QQVGA dimensions. (20k)160128 20,4805:4UNNAMEDUNNAMEDA shared size for older portable video game systems. The nearly-square (but landscape) aspect ratio and coarse pixel resolution gave these games a characteristic visual style. Colour depth ranged from 4 colours (2 bpp) with the original Game Boy, through 16–32 colours (4–5 bpp) with the Game Gear, to a maximum of 56 colours (equivalent of 6 bpp) from a wider palette with the Game Boy Color. Also appears as a YouTube resolution option ("144p"). (23k)160144 23,04010:9 (effectively 4:3 (non-square pixels) on Game Gear)2 bpp (6 bpp effective)HQVGAHalf Quarter Video Graphics ArrayUsed with some smaller, cheaper portable devices, including the Nintendo Game Boy Advance. (38k)240160 38,4003:2ST Low/Med ResolutionAtari ST (etc.) Colour, Broadcast-standardAtari ST line. Colour modes using NTSC or PAL-compliant televisions, and monochrome, composite video or RGB-component monitors.,640200 128,0004:3 (or 16:5 and 16:10 with square pixels)2–4 bpp for ST, 2–15 bpp on the Falcon.CGAColor Graphics AdapterIntroduced in 1981 by IBM, as the first colour display standard for the IBM PC. The standard CGA graphics cards were equipped with 16 kB video RAM. (128k) (64k) (32k)640200 128,00016:516:10/8:54:5 (effectively 4:3 on CRTs; various aspects on LCDs)1 bpp2 bpp4 bppQVGAQuarter Video Graphics ArrayHalf the resolution in each dimension as standard VGA. First appeared as a VESA mode (134h=256 color, 135h=Hi-Color) that primarily allowed character text with graphics, and should not be confused with CGA (); QVGA is normally used when describing screens on portable devices (PDAs, pocket media players, feature phones, smartphones, etc.). No set colour depth or refresh rate is associated with this standard or those that follow, as it is dependent both on the manufacturing quality of the screen and the capabilities of the attached display driver hardware, and almost always incorporates an LCD panel with no visible line-scanning. However, it would typically be in the 8-to-12 bpp (256–4096 colours) through 18 bpp (262,144 colours) range. (77k)320240 76,8004:3TV ComputerNon-interlaced TV-as-monitorVarious Apple, Atari, Commodore, Sinclair, Acorn, Tandy and other home and small-office computers introduced from 1977 through to the mid-1980s. They used televisions for display output and had a typical usable screen resolution from 102–320 pixels wide and usually 192–256 lines high, in non-interlaced (NI) mode for a more stable image (displaying a full image on each /-second field, instead of splitting it across each frame). The limited resolution led to displays with a characteristic wide overscan border around the active area. Some more powerful machines were able to display higher horizontal resolutions—either in text-mode alone or in low-colour bitmap graphics, and typically by halving the width of each pixel, rather than physically expanding the display area—but were still confined in the vertical dimension by the relatively slow horizontal scanning rate of a domestic TV set. These same standards—albeit with progressively greater colour depth and upstream graphical processing ability—would see extended use and popularity in TV-connected game consoles right through to the end of the 20th century. NI (high-end), NI (typical), NI (low-end)640256 163,8404:3 (non-square pixels)1–4 bpp typical, 2 or 3 bpp common.WQVGA Wide Quarter Video Graphics ArrayEffectively the total resolution ( in each dimension) of "Full HD", but with the height aligned to an 8-pixel "macroblock" boundary. Common in small-screen video applications, including portable DVD players and the Sony PSP. (131k)480272 130,560c. 1% narrower than 16:9 (30:17 exact)Mac Mono 9"Original Apple Macintosh displayThe single fixed-screen mode used in first-generation (128k and 512k) Apple Mac computers, launched in 1984, with a monochrome 9" CRT integrated into the body of the computer. Used to display one of the first mass-market full-time GUIs, and one of the earliest non-interlaced default displays with more than 256 lines of vertical resolution. (Early models used a screen; both standards are cut down from the of the preceding Lisa model) (175k)512342 175,104Very nearly 3:2 (to within 0.2%); 256:171 exact. Displayed with square pixels on a moderately wide-screen monitor (equivalent to 16:10.67 in modern terms).1 bppHerculesA monochrome display capable of sharp text and graphics for its time. Very popular with the Lotus 1-2-3 spreadsheet application, which was one of PC's first killer apps. Introduced in 1982. (251k)720348 250,56060:29 (effectively 4:3)1 bppEGAEnhanced Graphics AdapterIntroduced in 1984 by IBM. A resolution of pixels of 16 different colours in 4 bits per pixel (bpp), selectable from a 64-colour palette in 2 bits per each of red-green-blue (RGB) unit. Other commonly used modes were the existing CGA and resolutions in 4 bpp, with a fixed palette corresponding to the 16 colours available in CGA text mode, allowing an EGA card to be used in full colour with an unmodified CGA monitor by setting the correct DIP switch options; plus full EGA resolution (and CGA hi-res) in monochrome, if installed memory was insufficient for full colour at above . (224k), (128k), (64k)640350 224,00064:35, 16:5 and 16:10/8:5 (all effectively 4:3)4 bppMDAMonochrome Display AdapterThe original standard on IBM PCs and IBM PC XTs with 4 kB video RAM. Introduced in 1981 by IBM. Supports text mode only. (252k)720350 252,00072:35 (effectively 4:3 (non-square pixels) on CRTs but could be a variety of aspects on LCDs)1 bppOrchid Graphics AdapterA monochrome display that expanded Monochrome Display Adapter's capabilities with graphics. Introduced in 1982.720350 252,00072:35 (effectively 4:3 (non-square pixels) on CRTs but could be a variety of aspects on LCDs)1 bppST High ResolutionAtari ST (etc.) Monochrome, proprietary standardAtari ST line. High resolution monochrome mode using a custom non-interlaced monitor with the slightly lower vertical resolution (in order to be an integer multiple of low and medium resolution and thus utilize the same amount of RAM for the framebuffer) allowing a "flicker free" 71.25 Hz refresh rate, higher even than the highest refresh rate provided by VGA. All machines in the ST series could also use colour or monochrome VGA monitors with a proper cable or physical adapter, and all but the TT could display at 71.25 Hz on VGA monitors.640400 256,0004:3 (or 16:10 with square pixels)1 bpp for ST, on the Falcon: 1-8 bpp grayscale on the ST monochrome monitor, and 8 bpp colour on VGA/multisync monitors.PowerBook internal panelPowerBook, early generationsThe first PowerBook, released in 1991, replaced the original Mac Portable (basically an original Mac with an LCD, keyboard and trackball in a lunchbox-style shell), and introduced a new greyscale screen. This was joined in 1993 with the PowerBook 165c, which kept the same resolution but added colour capability similar to that of Mac II (256 colours from a palette of 16.7 million). (256k)640400 256,00016:10/8:5 (square pixels)8 bppProfessional Graphics ControllerWith 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 high-resolution, full-colour graphics at a 60 Hz frame rate. (307k)640480 307,2004:38 bppMCGAMulti-Color Graphics ArrayIntroduced by IBM on ISA-based PS/2 models in 1987, with reduced cost compared to VGA. MCGA had a 256-colour (from a 262,144 colour palette) mode, and a mode only in monochrome due to 64k video memory, compared to the 256k memory of VGA. (307k), (64k)640480 307,2004:3 (square pixels)16:10 (effectively 4:3)8 bpp1 bppVGAVideo Graphics ArrayIntroduced on MCA-based PS/2 models in 1987, it replaced the digital TTL signaling of EGA and earlier standards with analog RGBHV signaling, using the synonymous VGA connector. As with EGA, the VGA standard actually encompasses a set of different resolutions; is sometimes referred to as "VGA resolution" today, however as per the original standard this mode actually only supports 16 colours (4 bpp) at 60 Hz. Other common display modes also defined as VGA include at 256 colours (8 bpp) (standard VGA resolution for DOS games that stems from halving the pixel rate of , but doubling color depth) and a text mode with pixels; these modes run at 70 Hz and use non-square pixels, so 4:3 aspect correction is required for correct display.