A monochrome monitor is a type of cathode ray tube (CRT) computer monitor that was very common in the early years of computing from the 1960s to the 1980s. Then monitors with multiple colors became cheaper and more popular. They are still used in some systems.
Unlike color monitors, which can display text and graphics in multiple colors using varying intensities of red, green, and blue; monochrome monitors have a single phosphor color. All text and graphics are displayed in that single color. Some monitors had the ability to vary the brightness of each individual pixel, creating the illusion of depth of color (as occurs on black and white television).
Monochrome monitors usually came in one of three colors: if phosphor P1 was used the color was green, if phosphor P3 was used it was amber. If P4 phosphor was used, the color was off-white, the latter being the same phosphor used in black and white CRT televisions.
At the time, amber-colored monitors were sold as a way of not stressing the eye so much, an affirmation that lacked scientific evidence.
Monochrome monitors are particularly sensitive to screen burn, because the phosphor used was very high intensity. So static images for a long time could cause problems on the screen. This is where the first screen savers came from.
Another common effect on these monitors is the so-called «ghosting» effect, a faint glow of previously displayed content as the screen blanks. Sometimes done on purpose on certain screens to avoid the flickering effect of the monitor’s refresh rate.
Burnt monochrome CRT monitor, even visible when monitor was completely turned off. In this case it is a work of art by artist Steven Lee. (public domain image)
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