Before Computers: Calculation and Automation
Punched Cards: From Weaving to the Census
Distinguish storing instructions from storing data on a physical medium.
In this lesson
Lesson goals
Distinguish storing instructions from storing data on a physical medium.
The idea explained
Jacquard demonstrated a card-controlled loom in 1801: changing the cards changed the woven pattern. In the 1890 US census, Herman Hollerith’s electric tabulating system processed population records transferred to punched cards. The uses differ: loom cards guide operations, whereas census cards encode records to count and classify. Their shared insight is machine-readable information held on a removable medium.
Dates and milestones
- 1801: Jacquard demonstrates a punched-card-controlled loom.
- 1890: Hollerith’s electric tabulating system is used for the US census.
Why was this a turning point?
Information could change without rebuilding the whole mechanism, clarifying the separation between machinery and its inputs.
Activity: try before reading the answer
Encode city and age group on a paper record. Are these instructions or data? What about a card specifying the next weaving action?
Answer and explanation
The population record is data about a person; the control card specifies an action. Interpretation, not the card material, determines its role.