Why was it needed?

Rapid population growth made hand tabulation of census records increasingly costly and time-consuming. Hollerith developed equipment to make repeated statistical counts from encoded records, building on earlier methods of recording and sorting data. [1,2]

How did it work?

Clerks punched cards to encode individual records, then placed each card in a manually operated reading press. Pins passed through punched holes to complete circuits; electromagnets advanced counters on the tabulator. A sorting apparatus assisted with grouping cards for additional analyses. The 1890 system relied on operators to insert cards and record readings; it was not a self-feeding electronic computer. [1–3]

What did it change?

The system accelerated tabulation of large collections of records. Later versions added greater arithmetic capabilities and eventually automatic card feeding. Hollerith's business was among the predecessors of IBM, and punched-card processing later became important in accounting and business administration. [2–4]

The connection to automation

Encoded data triggered repeatable machine responses. Card holes acted as stored information, electrical contacts detected them, and electromechanical counters changed accordingly. Modern controllers also act on structured inputs, though digital computers use very different circuitry, software and storage. Hollerith's system mechanized information processing while leaving card preparation and handling to people.

Scholarly and primary sources

1. Smithsonian National Museum of American History. Hollerith Tabulating Machine, collection record.
2. U.S. Census Bureau. The Hollerith Machine.
3. Columbia University Computing History. Hollerith 1890 Census Tabulator.
4. Smithsonian Institution. From Herman Hollerith to IBM.