“Tempest for Eliza” is a program written by Erik Thiele to demonstrate the RF transmission properties of CRT monitors. The program is capable of transmitting sound over AM frequencies just by the unique way it drives the monitor. The electromagnetic emissions of CRTs can be a security problem as demonstrated by Van Eck phreaking, watching someone’s screen just by collecting RF transmissions. In the late ’90s Ross Anderson developed software to help reduce the RF transmissions of monitors. These specialized fonts combined with shielding can greatly reduce the risk of attack and is something the NSA has been researching for many years.