See color key
A computer terminal that displays green characters on a dark background. Widely used in the early days of mainframes and minicomputers, as well as in the days of DOS, the character-based green screen gave way to the graphics-based interfaces of Windows and Mac.
From Green Screen to the Web
CA Technologies' Advantage Integration Server transforms legacy applications (top) into graphics-based documents (bottom) that can be accessed via a Web browser. (Screen examples courtesy of CA Technologies, Inc.)