Monochrome monitor

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An amber monochrome SVGA computer monitor, manufactured in 2007, displaying the Wikipedia main page. Note how monochrome monitors display "color" by using varying shades of lightness and darkness.

An IBM computer with a green monochrome monitor.

Monochrome monitors are a type of computer display which were very common in the early days of computing, from the 1960s through the 1980s, before the advent of color monitors. They are still used today in some computerized cash register systems, amongst other select applications.

Unlike color monitors, which display text and graphics in multiple colors through the use of alternating-intensity red, green, and blue phosphors, monochrome monitors have only one color of phosphor (mono = one, chrome = color). All text and graphics are displayed in that color. Some monitors have the ability to vary the brightness of individual pixels, thereby creating the illusion of depth and color, exactly like a black-and-white television.

Monochrome monitors are available in three colors: if the P1 phosphor is used, the screen is green monochrome. If the P3 phosphor is used, the screen is amber monochrome. If the P4 phosphor is used, the screen is white monochrome (known as "page white"); this is the same phosphor as used in early television sets.

Monochrome monitors, pixel-for-pixel, produce sharper text and images than color CRT monitors. This is because on a monochrome monitor, each pixel is made up of one phosphor, located in the dead center of the pixel; whereas on a color monitor, each pixel is made up of three phosphors (one red, one blue, one green), none of which are in the center of the pixel. Color LCD monitors, however, do not suffer from this malady and therefore are just as sharp as monochrome CRT monitors. Because of their superior sharpness over color CRT monitors, monochrome monitors were used in almost all dumb terminals; and they still enjoy use in text-based applications such as computerized cash registers and order terminals (such as those seen at many fast-food restaurants).

Monochrome monitors are particularly susceptible to screen burn (hence the advent, and name, of the screen saver), on account of the fact that the phosphors used are very high-intensity. Another effect of the high-intensity phosphors is an effect known as "ghosting", wherein a dim afterglow of the screen's contents is briefly visible after the screen has been blanked. This has a certain place in pop culture, as evidenced in movies such as The Matrix, amongst other places.