Jay Forrester and Robert Everett, working
for the United States Navy, completed the construction of ' Whirlwind,'
a 'real-time computer,' taking twice the space of ENIAC, which
could constantly monitor its inputs, making it suitable for simulations.
In the course of its development, Forrester devised 'magnetic-core
memory.' Whirlwind's success caused the U. S. Air Force
to fund Project Lincoln, which used Whirlwind as the test bed
for the air defense system. This system required analog-digital
tele-communication and its engineers built a device called a modulator-demodulator,