Before microprocessors and silicon chips, computing power was measured in thousands of vacuum tubes, miles of copper wiring, and rooms cooled by industrial refrigeration units. In 1945, the ENIAC (Electronic Numerical Integrator and Computer) at the University of Pennsylvania operated over 17,000 vacuum tubes, performing 5,000 additions per second to calculate artillery ballistic firing tables.
By 1964, IBM introduced the landmark System/360 family—the first modular computer architecture that allowed businesses to upgrade processors while preserving existing software investments.
| System | Year | Logic Elements | Primary Memory | Input / Output Media |
|---|---|---|---|---|
| ENIAC | 1945 | 17,468 Vacuum Tubes | Vacuum tube accumulators (20 words) | IBM Card Reader & Punch |
| UNIVAC I | 1951 | 5,200 Vacuum Tubes | Mercury delay line memory (1,000 words) | UNISERVO Magnetic Metal Tape |
| IBM 7090 | 1959 | 50,000+ Discrete Transistors | Magnetic Core Memory (32K 36-bit words) | IBM 729 Magnetic Tape Units |
| IBM System/360 | 1964 | Solid Logic Technology (Hybrid microcircuits) | Magnetic Core (Up to 1 MB) | Punched cards, magnetic drums, 2311 disk drives |
Invented by Herman Hollerith for the 1890 US Census, the 80-column punched card became the universal medium for entering source code and business records. Each card represented exactly one line of FORTRAN, COBOL, or Assembly code: