The Screen, light & electricity as writing medium

Step forward in creating a new digital medium was the development of the screen as a new writing surface. Actually seeing a screen, attached to a computer, glowing with dots that were constantly refreshed and thus able to be manipulated and rearranged must have been one of the physical experiences that prepared researchers to understand that a computer would have graphical potential. The first computer to have such a screen appears to be Electronic Delay Storage Automatic Calculator (EDSAC) built for Cambridge University in England in 1949. Three cathode ray tubes were built into the interface, the screens monitored the content of the computer's registers, and memory; this was the amongst the first Computers to use a memory to store its programmes. ~ Page 303