Monochrome monitor

A monochrome monitor is a type of computer monitor in which computer text and images are displayed in varying tones of only one color, as opposed to a color monitor that can display text and images in multiple colors. They were very common in the early days of computing, from the 1960s through the 1980s, before color monitors became widely commercially available. They are still widely used in applications such as computerized cash register systems, owing to the age of many registers. Green screen was the common name for a monochrome monitor using a green "P1" phosphor screen; the term is often misused to refer to any block mode display terminal, regardless of color, e.g., IBM 3279, 3290.

Abundant in the early-to-mid-1980s, they succeeded Teletype terminals and preceded color CRTs and later LCDs as the predominant visual output device for computers.

CRT Design

The most common technology for monochrome monitors was the CRT, although other technologies, e.g., plasma displays, were also used.

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 means "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, thereby creating the illusion of depth and color, exactly like a black-and-white television.

Typically, only a limited set of brightness levels was provided to save display memory which was very expensive in the '70s and '80s.