Monochrome monitors are a very common type of CRT computer monitor in the early days of computing, from the 1960s to the 1980s, before color monitors became popular. They are still widely used in applications such as computerized cashier systems, due to the age of many registers. Green screen is the common name for monochrome monitors using the green "P1" phosphor screen.
Abundant in the early to mid-1980s, they managed the Teletype terminal and preceded the color of the CRT and then the LCD as the primary visual output device for the computer.
Video Monochrome monitor
Design
Unlike color monitors, which display text and graphics in different colors through the use of alternating red, green, and blue phosphors, monochrome monitors have only one phosphorous color ( mono meaning "one", and chrome means "color"). All text and graphics are displayed in that color. Some monitors have the ability to vary the brightness of individual pixels, thus creating the illusion of depth and color, just like black and white television.
Usually, only a limited set of brightness levels are provided to save a very expensive display memory in the 70s and 80s. Both normal/bright or normal/dim (1 bit) per character as in VT100 or black/white per pixel on 128K or black Macintosh, dark gray, light gray, white (2bit) per pixel like NeXT MegaPixel Display.
Monochrome monitors are usually available in three colors: if P1 phosphorus is used, the screen is monochrome green. If P3 phosphorus is used, the screen is a yellow monochrome. If P4 phosphorus is used, the screen is a white monochrome (known as "white paper"); this is the same phosphor as used on the initial television set. Amber screen is claimed to increase ergonomics, especially by reducing eye strain; This claim seems to have little scientific basis.
Maps Monochrome monitor
Usage
Notable examples of early monochrome monitors were the VT100 from Digital Equipment Corporation, released in 1978, and IBM 5151, which accompanied the IBM PC 5150 model in the 1981 release.
The 5151 series is designed to work with the monochrome Display Adapter (MDA) PC only graphics card, but the Third Party Hercules Graphics Card is a popular companion for the 5151 display due to its relatively high resolution of high resolution 720m â € "348 monochrome pixel graphics capabilities, widely used for business presentation graphics generated from spreadsheets such as Lotus 1-2-3. This resolution is much higher than the alternative IBM Color Graphics Adapter 320ÃÆ'â € "200 pixels, or 640ÃÆ'â €" 200 pixels standard graphics. It can also run most programs written for standard CGA card graphics modes. Monochrome monitors continue to be used, even after the introduction of the high-resolution color IBM Enhanced Graphics Adapter and the standard Video Graphics Array in the late 1980s, for dual-monitor applications.
Clarity
Pixels for pixels, monochrome monitors deliver sharper text and images than color CRT monitors. This is because monochrome monitors consist of a continuous phosphor layer and sharpness can be controlled by focusing electron beam; while on a color monitor, each pixel consists of three phosphor dots (one red, one blue, one green) separated by the mask. Monochrome monitors are used in almost all dumb terminals and are still widely used in text-based applications such as computerized cash registers and sales point systems because of their superior sharpness and better readability.
Some green screen displays come with a full/intense phosphor layer, making the characters very clear and sharply defined (making them easy to read) but producing spark effects (sometimes called "ghost images") when text scrolled down the screen or when a myriad of information quickly replaced with others such as in top/bottom page processing operations. Other green screens avoid the effects of heavy glow, but with the cost of drawing more pixelated characters. The 5151, among others, has brightness and contrast controls to allow users to set up their own compromises.
The ghosting effect of the now obsolete green screen has become an appealing visual stenography for computer-generated text, often in a "futuristic" setting. The opening title of the first Ghost in the Shell movie and the Matrix source code of the Matrix trilogy science fiction film clearly shows a computer screen with shaded green text. The green text is also displayed on the Swan computer in the Lost series.
Screen burn
Monochrome monitors are particularly vulnerable to screen burning (hence the emergence, and name, screensaver), because the phosphor used has very high intensity. Another effect of high intensity phosphorus is an effect known as "ghosting", in which a gloomy glow from the content of the screen is briefly visible after the screen has been blanked. It has a particular place in pop culture, as evidenced in movies like The Matrix .
This ghosting effect is deliberate on some monitors, known as "old persistency" monitors. It uses a relatively long period of phosphorus decay to reduce wrinkles and eye strain.
See also
- IBM 3270
- IBM 5250
References
Source of the article : Wikipedia
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