ENIAC and Early Mainframes

The ENIAC (Electronic Numerical Integrator and Computer), completed in 1945, is often considered the first general-purpose electronic computer. It filled a 30-by-50-foot room and weighed 30 tons. The ENIAC and its contemporaries required specially designed rooms with raised floors for cooling, complex wiring systems, and substantial power supplies.

These early mainframes were primarily used by government agencies, universities, and large corporations for scientific calculations, data processing, and business operations. The rooms that housed these machines can be considered the first data centers, though they were a far cry from today's facilities.