The term '40s-'50s Giant Brain' refers to the ENIAC (Electronic Numerical Integrator and Computer), which was the first large-scale, general-purpose electronic computer. It was developed in the 1940s and 1950s by a team of scientists and engineers at the University of Pennsylvania. The ENIAC was capable of performing complex calculations and was used for a variety of applications, including weather forecasting, nuclear weapons research, and code breaking. It was a revolutionary development in computing technology and laid the groundwork for modern computers.